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CONTEXT: Neuregulin 1 (NRG1), a growth factor involved in neurodevelopment, myelination, neurotransmitter receptor expression, and synaptic plasticity, first joined the list of candidate genes for schizophrenia when a 7-marker haplotype at the 5' end of the gene (Hap(ICE)) was shown to be associated with the disorder in the Icelandic population. Since then, more genetic and functional evidence has emerged, which supports a role for NRG1 in the development of schizophrenia. OBJECTIVE: To determine the contribution of NRG1 to susceptibility for schizophrenia in a northern Swedish isolated population. DESIGN: Detailed linkage disequilibrium (LD)-based patient-control association study. This is the first study to type and analyze the 7 Hap(ICE) markers and a set of 32 HapMap tagging single-nucleotide polymorphisms (SNPs) that represents variants with a minor allele frequency of at least 1% and fully characterizes the LD structure of the 5' part of NRG1. SETTING: Outpatient and inpatient hospitals. PARTICIPANTS: A total of 486 unrelated patients with schizophrenia and 514 unrelated control individuals recruited from a northern Swedish isolated population. MAIN OUTCOME MEASURES: Association between markers and disease. RESULTS: Analysis of the Hap(ICE) markers showed the association of a 7-marker and 2-microsatellite haplotype, different from the haplotypes associated in the Icelandic population and overrepresented in northern Swedish control individuals. Subsequently, a more detailed analysis that included all 37 genotyped SNPs was performed by investigating haplotypic association, dependent and independent of LD block structure. We found significant association with 5 SNPs located in the second intron of NRG1 (.007

Through active reuptake of serotonin into presynaptic neurons, the serotonin transporter (5-HTT) plays an important role in regulating serotonin concentrations in the brain, and it is the site of binding for tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs). Therefore it has been hypothesized that this transporter is involved in the etiology of bipolar (BP) disorder. Inconsistent association study results for the SLC6A4 gene encoding 5-HTT reported in literature emphasize the need for more systematic and detailed analyses of this candidate gene. We performed an extensive analysis of SLC6A4 on DNA of 254 BPI patients and 364 control individuals from a Northern Swedish isolated population. This analysis consisted of a HapMap LD-based association study including three widely investigated polymorphisms (5-HTTVNTR, 5-HTTLPR, and rs3813034), a copy-number variation (CNV) analysis and a mutation analysis of the complete coding sequence and the 3'-UTR of SLC6A4. No single marker showed statistically significant association with BPI, nor did any of the haplotypes. In the mutation analysis 13 novel variants were detected, including 2 amino acid substitutions M389V and I587L, but these are probably not implicated in risk for BP. No deletions or duplications were detected in the CNV analysis. We conclude that variation in the SLC6A4 gene or its regulatory regions does not contribute to the susceptibility for BP disorder in the Northern Swedish population.

GPR50 is a G protein-coupled receptor, located on Xq28 and related to the melatonin receptor family. It is suggested as a functional and positional candidate gene for bipolar disorder (BP). Recently an insertion/deletion polymorphism in GPR50, Delta502-505, was found to be associated with BP in a Scottish association sample (P=0.007). When the analysis was restricted to female subjects, the association increased in significance (P=0.00023). We attempted to replicate this finding in a Northern Swedish association sample, but no significant association was detected (P=0.7, women only: P=0.65).

Objectives: Dysfunction of the hypothalamus-pituitary-adrenal (HPA) axis is one of the most consistent findings in the pathophysiology of mood disorders. The potential role of genes related to HPA axis function has been investigated extensively in major depression. However, in bipolar disorder (BPD) such studies are scarce. We performed a systematic HapMap-based association study of six genes crucial for HPA axis function in relation to BPD.

Methods: Haplotype tagging single nucleotide polymorphisms (htSNPs) were selected in order to identify all haplotypes with a frequency of more than 1% in the genes encoding the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), corticotrophin releasing hormone receptor 1 (CRH-R1) and 2 (CRH-R2), CRH binding protein (CRH-BP), and FK binding protein 5 (FKBP5). This resulted in a total selection of 225 SNPs that were genotyped and analyzed in 309 BPD patients and 364 matched control individuals all originating from an isolated northern Swedish population.

Results: Consistent evidence for an association with BPD was found for NR3C1, the gene encoding GR. Almost all SNPs in two adjacent haplotype blocks contributed to the positive signal, comprised of significant single marker, sliding window, and haplotype-specific p-values. All these results point to a moderately frequent (10-15%) susceptibility haplotype covering the entire coding region and 3 > untranslated region (UTR) of NR3C1.

Conclusions: This study contributes to the growing evidence for a role of the glucocorticoid receptor gene (NR3C1) in vulnerability to mood disorders, and BPD in particular, and warrants further in vitro investigation of the at-risk haplotypes with respect to disease etiology. However, this association might be restricted to this specific population, as it is observed in a rather small sample from an isolated population without replication, and data from large meta-analyses for genome-wide association studies in BPD do not show the GR as a very strong candidate.

Identification of novel candidate genes for schizophrenia (SZ) and bipolar disorder (BP), two psychiatric disorders with large epidemiological impacts, is a key research area in neurosciences and psychiatric genetics. Previous evidence from genome-wide studies suggests an important role for genes involved in synaptic plasticity in the risk for SZ and BP. We used a convergent genomics approach, combining different lines of biological evidence, to identify genes involved in the cAMP/PKA/CREB functional pathway that could be novel candidates for BP and SZ: CREB1, CREM, GRIN2C, NPY2R, NF1, PPP3CB and PRKAR1A. These 7 genes were analyzed in a HapMap based association study comprising 48 common SNPs in 486 SZ, 351 BP patients and 514 control individuals recruited from an isolated population in Northern Sweden. Genetic analysis showed significant allelic associations of SNPs in PRKAR1A with SZ and of PPP3CB and PRKAR1A with BP. Our results highlight the feasibility and the importance of convergent genomic data analysis for the identification of candidate genes and our data provide support for the role of common inherited variants in synaptic genes and their involvement in the etiology of BP and SZ.

The immunoglobulin V(H) gene mutation status can divide B-cell chronic lymphocytic leukaemia (CLL) into two entities with a different clinical course. Cases with unmutated V(H) genes, considered to evolve from pregerminal centre (GC) cells, have a worse outcome compared to cases showing mutated V(H) genes, that is, post-GC derived. Also, telomere length has been reported to be of prognostic significance in CLL. Interestingly, telomerase becomes activated during the GC reaction and an elongation of the telomeres occurs in GC B cells. We performed telomere length and V(H) gene analysis in a series of 61 CLL cases, in order to investigate if the unique telomere lengthening shown in GC B cells could reflect the telomere status in the two subsets of mutated and unmutated CLL. A novel association was found between V(H) gene mutation status and telomere length, since significantly shorter telomeres were demonstrated in the unmutated group compared to the mutated group (mean length 4.3 vs 6.3 kbp). Shorter telomeres also constituted a subgroup with a worse prognosis than cases with longer telomeres (median survival 59 vs 159 months). Furthermore, the Ig gene sequence data revealed that samples with high mutations frequency (>6%) had long telomeres ( approximately 8 kbp). Thus, both the telomere and V(H) gene mutation status in CLL appear linked, which may reflect the proliferative history of the clonal cells with regard to the GC reaction.

Determination of telomere length is traditionally performed by Southern blotting and densitometry, giving a mean telomere restriction fragment (TRF) value for the total cell population studied. Fluorescence in situ hybridization (FISH) of telomere repeats has been used to calculate telomere length, a method called quantitative (Q)-FISH, We here present a quantitative flow cytometric approach, Q-FISHFCM, for evaluation of telomere length distribution in individual cells based on in situ hybridization using a fluorescein-labeled peptide nucleic acid (PNA) (CCCTAA)(3) probe and DMA staining with propidium iodide, A simple and rapid protocol with results within 30 h was developed giving high reproducibility, One important feature of the protocol was the use of an internal cell line control, giving an automatic compensation for potential differences in the hybridization steps. This protocol was tested successfully on cell lines and clinical samples from bone marrow, blood, lymph nodes and tonsils. A significant correlation was found between Southern blotting and Q-FISHFCM telomere length values (P = 0.002), The mean sub-telomeric DNA length of the tested cell lines and clinical samples was estimated to be 3.2 kbp, With the Q-FISHFCM method the fluorescence signal could be determined in different cell cycle phases, indicating that in human cells the vast majority of telomeric DNA is replicated early in S phase.

The replication timing of telomeres seems to differ between species. Yeast telomeres are late replicating, whereas limited data from very few human cell lines have indicated telomere replication throughout S phase. In the present study a series of permanent cell lines and patient samples was investigated using a flow cytometric approach for telomere length determination based on in situ hybridization using peptide nucleic acid probes and DNA staining. This method permits selective analysis of cells in specific phases of the cell cycle without perturbation of the cell cycle machinery. The timing of replication of telomeric C(3)TA(2) and T(2)AG(3) repeats was found to differ between individual samples and could precede or be concomitant with the replication of bulk DNA. Replication of the T(2)AG(3) strand seemed to occur somewhat later than that of the C(3)TA(2) strand in some samples. (GTG)(n) and other repetitive sequences generally showed a replication pattern similar to that of the bulk of DNA with slightly individual differences, whereas centromeric DNA repeats consistently replicated within a short time frame in late S phase. The apparent variability in replication timing seen for telomeric DNA might suggest individual differences in firing of replication origins.

The immunoglobulin V-H gene mutation status can divide B-cell chronic lymphocytic leukaemia (CLL) into two entities with a different clinical course. Cases with unmutated V-H genes, considered to evolve from pregerminal centre (GC) cells, have a worse outcome compared to cases showing mutated VH genes, that is, post-GC derived. Also, telomere length has been reported to be of prognostic significance in CLL. Interestingly, telomerase becomes activated during the GC reaction and an elongation of the telomeres occurs in GC B cells. We performed telomere length and VH gene analysis in a series of 61 CLL cases, in order to investigate if the unique telomere lengthening shown in GC B cells could reflect the telomere status in the two subsets of mutated and unmutated CLL. A novel association was found between VH gene mutation status and telomere length, since significantly shorter telomeres were demonstrated in the unmutated group compared to the mutated group (mean length 4.3 vs 63 kbp). Shorter telomeres also constituted a subgroup with a worse prognosis than cases with longer telomeres (median survival 59 vs 159 months), Furthermore, the I-g gene sequence data revealed that samples with high mutations frequency (> 6%) had long telomeres (similar to 8 kbp). Thus, both the telomere and VH gene mutation status in CLL appear linked, which may reflect the proliferative history of the clonal cells with regard to the GC reaction. (C) 2003 Cancer Research UK.

There is bidirectional comorbidity between anxiety/depression and irritable bowel syndrome (IBS). To investigate the prevalence of IBS symptoms, and factors associated with gastrointestinal symptoms in patients with recurrent depressive disorder. Patients (n = 95) with recurrent type of major depression according to DSM-IV criteria and sex- and age-matched controls (n = 190) were sent questionnaires investigating symptoms of IBS [Gastrointestinal Symptom Rating Scale (GSRS)-IBS] and symptoms of anxiety and depression [Hospital Anxiety and Depression Scale (HADS)]. Medical records were checked over a 10-year period for chronic somatic symptoms or diseases. Seventy-three patients with unipolar disorder (mean age 63.6 years SD 13.8; range 23–86 years) and 156 controls (mean age 59.2 years SD 11.6, range 21–85 years) responded. Patients with recurrent depression had higher GSRS-IBS scores and showed a strong correlation between symptoms of IBS and anxiety-depression (r_s = 0.54; P < 0.001). IBS symptoms were also associated with multiple pain symptoms, higher health-seeking behaviour and selective-serotonin-reuptake inhibitor intake. However, patients with recurrent depression (n = 46) in remission (HADS-Depression score <8) did not have more symptoms of IBS than controls (GSRS-IBS median score 6.0 vs 6.5; P = 0.46). There is a strong association between symptoms of IBS and symptoms of anxiety and depression, whereas depressive patients in remission do not have more IBS symptoms than controls.

Background

The catechol-O-methyltransferase (COMT) enzyme has a key function in the degradation of catecholamines and a functional polymorphism is val158met. The val/val genotype results in a three to fourfold higher enzymatic activity compared with the met/met genotype, with the val/met genotype exhibiting intermediate activity. Since pain syndromes as well as anxiety and depression are associated to low and high COMT activity respectively and these conditions are all associated with irritable bowel syndrome (IBS) we wanted for the first time to explore the relationship between the polymorphism and IBS.

Methodology/Principal Findings

867 subjects (445 women) representative of the general population and 70 consecutively sampled patients with IBS (61 women) were genotyped for the val158met polymorphism and the IBS patients filled out the Hospital-Anxiety-and-Depression-Scale (HADS) questionnaire, and an IBS symptom diary.

Results

There was a significantly higher occurrence of the val/val genotype in patients compared with controls (30% vs 20%; Chi² (1) 3.98; p = 0.046) and a trend toward a lower occurrence of the val/met genotype in IBS patients compared with controls (39% vs 49%; Chi² (1) 2.89; p = 0.089). Within the IBS patients the val/val carriers exhibited significantly increased bowel frequency (2.6 vs 1.8 stools per day; Chi² (1) 5.3; p = 0.03) and a smaller proportion of stools with incomplete defecation (41% vs 68%; Chi² (1) 4.3; p = 0.04) compared with the rest (val/met+met/met carriers). The val/val carriers also showed a trend for a smaller proportion of hard stools (0% vs 15%; Chi² (1) 3.2; p = 0.08) and a higher frequency of postprandial defecation (26% vs 21%; Chi² (1) 3.0; p = 0.08).

Conclusions/Significance

In this study we found an association between the val/val genotype of the val158met COMT gene and IBS as well as to specific IBS related bowel pattern in IBS patients.

AIM: To study if anxiety, depression and experience of stress are associated with gastrointestinal (GI) symptoms in patients with bipolar disorder.

METHODS: A total of 136 patients with bipolar disorder (mean age 49.9 years; 61% women) and 136 controls from the general population (mean age 51.0 years; 60% women) were included in the study. GI symptoms were assessed with The Gastrointestinal Symptom Rating Scale-irritable bowel syndrome (GSRS-IBS), level of anxiety and depression with The Hospital Anxiety and Depression Scale (HADS) and stress-proneness with Perceived Stress Questionnaire. Over a ten year period, all visits in primary care were retrospectively recorded in order to identify functional GI disorders.

RESULTS: In subjects with low total HADS-score, there were no significant differences in GI-symptoms between patients and controls (GSRS-IBS 7.0 vs 6.5, P = 0.513). In the patients with bipolar disorder there were significant correlations between all GSRS and HADS subscores for all symptom clusters except for "constipation" and "reflux". Factors associated to GI symptoms in the patient group were female sex (adjusted OR = 2.37, 95%CI: 1.07-5.24) and high HADS-Depression score (adjusted OR = 3.64, 95%CI: 1.07-12.4). These patients had also significantly more visits for IBS than patients with low HADS-Depression scores (29% vs 8%, P = 0.008). However, there was no significant differences in consulting behaviour for functional GI disorders between patients and controls (25% vs 17%, P = 0.108).

CONCLUSION: Female patients and patients with high HADS depression score reported significantly more GI symptoms, whereas patients with low HADS scores did not differ from control subjects.

Background/Aims: Gastrointestinal symptoms and hypothalamus-pituitary-adrenal (HPA) axis dysfunction are frequently observed in patients with major depression. The primary aim of the study was to investigate the relationship between HPA-axis function and self-perceived functional gastrointestinal symptoms in major depression.

Methods: Patients with major depression (n = 73) and controls representative of the general population (n = 146) underwent a weight-adjusted very low dose dexamethasone suppression test (DST). Patients and controls completed the Gastrointestinal Symptom Rating Scale-Irritable Bowel Syndrome (GSRS-IBS) and the Hospital Anxiety Depression Scale. Medical records of the patients were screened over a ten year period for functional gastrointestinal disorder and pain conditions.

Results: Patients with high GSRS-IBS scores (above median) exhibited HPA-axis hypersuppression more often than controls (defined by the lowest 10% cutoff of the post-DST cortisol values among controls, adjusted OR 7.25, CI 1.97-26.7) whereas patients with low GSRS-IBS scores did not differ from controls concerning their post-DST cortisol values. Patients who had consulted primary care for functional gastrointestinal disorder (P= 0.039), lumbago (P = 0.006) and chronic multifocal pain (P= 0.057) also exhibited an increased frequency of hypersuppression.

Conclusions: HPA-axis hypersuppression is associated with functional gastrointestinal symptoms in patients with major depression.

Bipolar disorder is associated with a long range of medical comorbidities, including migraine, diabetes, and cardiovascular disease. Bipolar disorder has also been associated with an increased risk of bone fractures. Osteoporosis is a reduction in bone mineral density, which leads to an increased risk for fragility fractures. Currently there is limited research on the association between bipolar disorder and osteoporosis. We aimed to study the association between high and low bone mineral density in relation to disease and treatment history in a sample of bipolar patients. We found that bipolar patients with high bone mineral density were more often on lithium medication, had a more active lifestyle and expressed lower current disease burden. Low mineral density was not associated with any of the addressed aspects of disease and treatment history. In conclusion our results support that patients on lithium treatment have higher bone mineral density; further studies are needed to address if lithium medication causes an increase in bone mineral density, and lowers the risk of bone fractures in bipolar disorder.

Background: Although bipolar disorder (BP) is associated with impaired quality of life (QOL), little is known about the clinical features associated with QOL. Better knowledge about this relationship may improve treatment.

Methods: This cross-sectional and retrospective study of 160 bipolar outpatients is part of an extensive study battery that includes patient-rated QOL with the World Health Organization QOL-100. The subscale "overall QOL" was used for analysis. QOL was divided into subgroups denoted "low", "mid", and "high". Clinical data such as disease-specific factors, treatment efforts, and lifestyle were gathered from personal interviews and medical records.

Results: Compared to mid QOL, single analysis adjusted for age and sex revealed that low QOL was associated with BP II diagnosis, no previous hospitalization, low grade of current lithium medication, high grade of current antiepileptic medication, short disease duration with lithium, long disease duration without lithium, inactive lifestyle, high BMI, young age, and pre-menopausal women. Compared to mid QOL, high QOL was associated with a hypomanic/manic first affective episode, low BMI, non-smoker, and not currently using anxiolytic or sedatives.

Limitations: No longitudinal QOL data were collected.

Conclusions: QOL for bipolar patients is determined by serval factors that potentially could be altered. To improve QOL, lithium prophylaxis and lifestyle factors seem the most promising.

Background: A hyperactive hypothalamic-pituitary-adrenal axis (HPA-axis) is a well-known phenomenon in bipolar disorder (BD). However, hypocortisolism has also been described and found associated with depression, low quality of life and cardiovascular risk factors in BD patients. Although the pathophysiology related to hypocortisolism in BD is largely unknown, hypocortisolism is associated with chronic stress exposure and after inducing an initial rise in cortisol long-term stress may result in a transition to hypocortisolism. BD patients are throughout life often exposed to chronic stress. We therefore hypothesized that higher age would be associated with lower HPA-axis activity especially among patients without previous mood stabilizing treatment. Methods: This cross-sectional study consisted of 159 bipolar outpatients and 258 controls. A low-dose-dexamethasone-suppression-test (DST) was used to measure HPA-axis activity. Results: Patients with BD showed a negative association between post DST cortisol and age (-3.0 nmol/l per year; p=0.007). This association gradually increased in subgroups that were naive to lithium (-7.7 nmol/l per year; p=0.001) and "all mood stabilizers" (-11.4 nmol/l per year; p=0.004). Patients exhibiting hypercortisolism were characterized by younger age and female gender, whereas patients exhibiting hypocortisolism were characterized by long disease duration without prophylactic lithium treatment as well as absence of current lithium medication. Limitations: Cross sectional study design. Conclusions: There was a negative association between HPA-axis activity and age in BD, rendering BD patients at risk for developing hypocortisolism. This association was most pronounced among patients without previous or current lithium prophylaxis.

Background: Cardiovascular disease (CVD) is one of the main causes of excess deaths in affective disorders. Affective disorders are associated with increased frequencies of CVD risk-factors such as obesity, dyslipidemia, and metabolic syndrome. Stress-induced chronic cortisol excess has been suggested to promote obesity and metabolic syndrome. Chronic stress with frequent or persisting hypothalamic-pituitary-adrenal-axis (HPA-axis) hyperactivity may, over time, lead to a state of low HPA-axis activity, also denoted hypocortisolism. A low-dose weight-adjusted dexamethasone-suppression-test (DST) is considered to be a sensitive measure of hypocortisolism.

Methods: 245 patients with recurrent depression or bipolar disorder and 258 controls participated in a low-dose DST and were also examined with regard to metabolic status.

Results: Patients with hypocortisolism (low post-DST cortisol) compared with patients without hypocortisolism (normal or high post-DST cortisol) exhibited increased odds ratios (OR) for obesity (OR=4.0), overweight (OR=4.0), large waist (OR=2.7), high LDL (OR=4.2), low HDL (OR=2.4), high LDL/HDL ratio (OR=3.3), high TC/HDL ratio (OR=3.4) and metabolic syndrome (OR=2.0). A similar pattern but less pronounced was also found in the control sample.

Limitations: The cross sectional study design and absence of analyses addressing lifestyle factors.

Conclusions: Our findings suggest that a substantial portion of the metabolic disorders and cardiovascular risk factors seen in recurrent affective disorders are found among individuals exhibiting hypocortisolism. This might indicate that long-term stress is a central contributor to metabolic abnormalities and CVD mortality in recurrent affective disorders.

Background: Depression in unipolar and bipolar disorders is associated with hypothalamic-pituitary-adrenal-axis (HPA-axis) hyperactivity. Also, unipolar disorder has recently been shown to exhibit HPA-axis hypoactivity. We studied for the first time how HPA-axis hypo-and hyperactivity relate to depression and disease burden in bipolar disorder. We were interested in studying hypocortisolism; characterized by increased HPA-axis negative feedback sensitivity and lower basal cortisol levels together with the opposite HPA-axis regulatory pattern of hypercortisolism. Methods: This cross-sectional study includes 145 type 1 and 2 bipolar outpatients and 145 matched controls. A dexamethasone-suppression-test (DST) measures the negative feedback sensitivity and a weight-adjusted very-low-dose DST was employed, which is sensitive in identifying hypocortisolism and hypercortisolism. The 25th and 75th percentiles of control post-DST values were used as cut-offs identifying patients exhibiting relative hypo-, and hypercortisolism. Self-report questionnaires were employed: Beck-Depression-Inventory (BDI), Montgomery-Asberg-Depression-Rating-Scale (MADRS-S), World-Health-Organization-Quality-of-Life-Assessment-100 and Global-Assessment-of-Functioning. Results: Patients exhibiting relative hypocortisolism expectedly exhibited lowered basal cortisol levels (p = 0.046). Patients exhibiting relative hypercortisolism expectedly exhibited elevated basal levels (p<0.001). Patients exhibiting relative hypocortisolism showed 1.9-2.0 (BDI, p = 0.017, MADRS-S, p = 0.37) and 6.0 (p<0.001) times increased frequencies of depression and low overall life quality compared with patients exhibiting mid post-DST values (eucortisolism). Adjusted Odds Ratios (OR:s) for depression ranged from 3.8-4.1 (BDI, p = 0.006, MADRS-S, p = 0.011) and was 23.4 (p<0.001) for life quality. Patients exhibiting relative hypercortisolism showed 1.9-2.4 (BDI, p = 0.017, MADRS-S, p = 0.003) and 4.7 (p<0.001) times higher frequencies of depression and low overall life quality compared with patients exhibiting eucortisolism. Adjusted OR: s for depression ranged from 2.2-2.7 (BDI, p = 0.068, MADRS-S, p = 0.045) and was 6.3 (p = 0.008) for life quality. Limitations: The cross-sectional design and lack of pre-established reference values of the DST employed. Conclusions: Relative hypocortisolism and relative hypercortisolism were associated with depression and lower life quality, providing novel insights into the detrimental role of stress in bipolar disorder.

Previous studies implicated centrosomal dysfunction as a source of various neuropsychiatric disorders, including schizophrenia (SZ). Two recent reports [Gurling et al., 2006; Datta et al., 2008. Mol Psychiatry] described an association between polymorphisms in the PCM1 gene and SZ in a UK/Scottish population. In this study, we aimed to replicate these findings in a Northern Swedish association sample of 486 research subjects with SZ and 512 unrelated control individuals. We genotyped 12 previously described SNP markers and carried out haplotype analyses using the same multi-marker haplotypes previously reported. Though we could not replicate the association with SNPs rs445422 and rs208747, we did observe a significant protective association with intronic SNP rs13276297. Furthermore, we performed a meta-analysis comprising 1,794 SZ patients and 1,553 controls, which confirmed the previously reported association with rs445422 and rs208747. These data provide further evidence that PCM1-though certainly not a major risk factor in the Northern Swedish population-cannot be ruled out as a contributor to SZ risk and/or protection, and deserves further replication in larger populations to elucidate its role in disease etiology.

In recent years, DISC1 has emerged as one of the most credible and best supported candidate genes for schizophrenia and related neuropsychiatric disorders. Furthermore, increasing evidence - both genetic and functional - indicates that many of its protein interaction partners are also involved in the development of these diseases. In this study, we applied a pooled sample 454 sequencing strategy, to explore the contribution of genetic variation in DISC1 and 10 of its interaction partners (ATF5, Grb2, FEZ1, LIS-1, PDE4B, NDE1, NDEL1, TRAF3IP1, YWHAE, and ZNF365) to schizophrenia susceptibility in an isolated northern Swedish population. Mutation burden analysis of the identified variants in a population of 486 SZ patients and 514 control individuals, revealed that non-synonymous rare variants with a MAF<0.01 were significantly more present in patients compared to controls (8.64% versus 4.7%, P = 0.018), providing further evidence for the involvement of DISC1 and some of its interaction partners in psychiatric disorders. This increased burden of rare missense variants was even more striking in a subgroup of early onset patients (12.9% versus 4.7%, P = 0.0004), highlighting the importance of studying subgroups of patients and identifying endophenotypes. Upon investigation of the potential functional effects associated with the identified missense variants, we found that similar to 90% of these variants reside in intrinsically disordered protein regions. The observed increase in mutation burden in patients provides further support for the role of the DISC1 pathway in schizophrenia. Furthermore, this study presents the first evidence supporting the involvement of mutations within intrinsically disordered protein regions in the pathogenesis of psychiatric disorders. As many important biological functions depend directly on the disordered state, alteration of this disorder in key pathways may represent an intriguing new disease mechanism for schizophrenia and related neuropsychiatric diseases. Further research into this unexplored domain will be required to elucidate the role of the identified variants in schizophrenia etiology.

Age-associated telomere shortening is a well documented feature of peripheral blood cells in human population studies, but it is not known to what extent these data can be transferred to the individual level. Telomere length (TL) in two blood samples taken at approximately 10 years interval from 959 individuals was investigated using real-time PCR. TL was also measured in 13 families from a multigenerational cohort. As expected, we found an age-related decline in TL over time (r = -0.164, P<0.001, n = 959). However, approximately one-third of the individuals exhibited a stable or increased TL over a decade. The individual telomere attrition rate was inversely correlated with initial TL at a highly significant level (r = -0.752, P<0.001), indicating that the attrition rate was most pronounced in individuals with long telomeres at baseline. In accordance, the age-associated telomere attrition rate was more prominent in families with members displaying longer telomeres at a young age (r = -0.691, P<0.001). Abnormal blood TL has been reported at diagnosis of various malignancies, but in the present study there was no association between individual telomere attrition rate or prediagnostic TL and later tumor development. The collected data strongly suggest a TL maintenance mechanism acting in vivo, providing protection of short telomeres as previously demonstrated in vitro. Our findings might challenge the hypothesis that individual TL can predict possible life span or later tumor development.

Telomere length is documented to have a hereditary component, and both paternal and X-linked inheritance have been proposed. We investigated blood cell telomere length in 962 individuals with an age range between 0 and 102 years. Telomere length correlations were analyzed between parent-child pairs in different age groups and between grandparent-grandchild pairs. A highly significant correlation between the father's and the child's telomere length was observed (r=0.454, P<0.001), independent of the sex of the offspring (father-son: r=0.465, P<0.001; father-daughter: r=0.484, P<0.001). For mothers, the correlations were weaker (mother-child: r=0.148, P=0.098; mother-son: r=0.080, P=0.561; mother-daughter: r=0.297, P=0.013). A positive telomere length correlation was also observed for grandparent-grandchild pairs (r=0.272, P=0.013). Our findings indicate that fathers contribute significantly stronger to the telomere length of the offspring compared with mothers (P=0.012), but we cannot exclude a maternal influence on the daughter's telomeres. Interestingly, the father-child correlations diminished with increasing age (P=0.022), suggesting that nonheritable factors have an impact on telomere length dynamics during life.

Activation of telomerase seems to be a prerequisite for immortalization and is found in permanent cell lines and most malignant tumors. Normal somatic cells are generally telomerase negative, except for bone marrow stem cells. Weak activity is also present in peripheral blood cells. In the present study strong telomerase activity was demonstrated in vivo in normal mature cells of the immune system, as well as in malignant lymphomas. Benign lymph nodes had lower telomerase activity than benign tonsils, which exhibited intermediate to high activity comparable with findings in malignant lymphomas. In benign tonsils the activity seemed to be restricted to germinal center B cells. In benign lymphoid tissues telomerase activity correlated with B-cell numbers and cell proliferation, but this was not observed in the lymphoma group. High-grade lymphomas exhibited higher levels of telomerase compared with low-grade cases. The data showed that in vivo activation of telomerase is a characteristic feature of germinal center B cells. Different signals for activation of telomerase are likely to exist, one of them being immune stimulation. The data suggest that telomerase activity in malignant lymphomas can be explained by an "induction and retention" model, ie, transformation occurs in a normal, mature B cell with reactivated telomerase, which is retained in the neoplastic clone.

Telomere maintenance executed by the action of telomerase seems to be a prerequisite for immortalization. Telomerase is found in most cell lines and malignant tumors. A telomerase-independent mechanism for telomere maintenance in Hodgkin's disease has been proposed in the absence of detectable telomerase activity. In this study, telomerase activity was detected in 31 of 77 Hodgkin's disease samples and a strong correlation between eosinophilia and absence of detectable telomerase activity was found. Purified eosinophils and specifically eosinophil-derived neurotoxin and eosinophilic cationic protein, both ribonucleases, were found to degrade telomerase. Purified neutrophils also exhibited weak telomerase degradative activity. Reanalysis of previously telomerase-negative Hodgkin's disease samples with eosinophilia using ribonuclease inhibitors resulted in the detection of telomerase activity. Ribonuclease-containing cells in vivo thus have a considerable impact on the detectability of telomerase. In Hodgkin's disease samples without eosinophilia, 24 of 27 exhibited telomerase activity at decreased levels compared with non-Hodgkin's lymphomas and at increased levels compared with reactive nodes indicative of a telomerase positive tumor component in Hodgkin's disease. Telomerase positivity of the Hodgkin's and Reed-Sternberg cells in vivo was also supported by high levels of telomerase expression in Hodgkin's disease cell lines. Based on our data, Hodgkin's lymphomas are potential targets for antitelomerase therapy.

Telomere length maintenance, usually executed by telomerase, is a prerequisite for an extended or infinite division potential. Nevertheless most telomerase positive normal cells exhibit telomere shortening. This study details the telomerase expression and telomere dynamics in purified tonsil B cell subsets during the germinal center (GC) reaction. Significant telomere lengthening was observed as naive B cells matured to centroblasts and when centroblasts matured further to centrocytes, resulting in an increase in telomere length of about 4 kbp determined by Southern blotting. Immunopurified cell populations were also studied by fluorescence in situ hybridization and flow cytometry (flow-FISH) confirming that the GC B cells exhibited lengthened telomeres. These data were further verified in unpurified tonsil cells by combining flow-FISH and immunophenotyping using selected surface markers. Centroblasts expressed high levels of telomerase activity, which was increased in centrocytes, whereas resting naive, activated naive and memory B cells were telomerase activity negative. Expression levels of the catalytic subunit (hTERT) RNA paralleled the telomerase activity levels. The unique telomere elongation in GC B cells permits extensive proliferation during the GC reaction and provides the memory cells with a substantial increase in division potential. Understanding the telomere biology of GC cells is important in defining requirements for telomere elongation in vivo, with implications for the normal immune system as well as for lymphomas, and could provide insights into how the division potential of cells can be manipulated in vitro.

The normal haematopoietic system harbours telomerase-competent cells with a capacity to upregulate the activity to notable levels in a telomere length-independent manner. Strong telomerase activity is found in progenitor stem cells and activated lymphocytes in vitro as well as in vivo, indicating that cells with high growth requirements can readily upregulate telomerase. Despite detection of telomerase activity, a gradual telomere erosion occurs in stem cells and lymphocytes, with significantly shortened telomeres at higher ages, a phenomenon that might be of importance for developing immunosenescence and exhausted haematopoiesis. In malignant haematopoietic disorders telomerase activity is a general finding with large differences in activity levels. The strongest telomerase expression has been shown in acute leukaemias and non-Hodgkin's lymphomas, especially high grade cases. There are indications that the level of activity might parallel tumour progression and be of prognostic relevance, but studies of larger patient materials are needed. An association between the cell cycle and telomerase activity exists, especially for normal haematopoietic cells, and induction of a differentiation programme in immortalised cell lines downregulates telomerase activity. The expression of telomerase activity seems to be regulated at different levels, since for immature bone marrow cells the level of activity seemed to parallel better the phenotype than the proliferation state. The frequent expression of telomerase in leukaemias and lymphomas makes these disorders interesting targets for future anti-telomerase therapy.

In a majority of malignant human tumors telomerase activity can be detected, suggesting an immortal phenotype. Expression of the reverse transcriptase subunit, hTERT, in the human telomerase complex is required for telomerase activity. The regulation of hTERT, from gene level to a fully functional protein, is still a poorly understood process. Increased copy number of the hTERT gene has been demonstrated in a significant portion of established cell lines and tumors of different origin but its relevance for telomerase activity levels is unclear. In the present study, we examined the hTERT gene copy number using fluorescence in situ hybridization (FISH) in samples from 64 colorectal carcinomas and an increased copy number (≥ 3 hTERT gene copies/nucleus) was observed in 31 cases (48%). No statistical association existed between hTERT gene copy number and hTERT RNA expression or telomerase activity. However, a significant relationship was found between an increase in hTERT gene copy number and p53 protein accumulation (p = 0.002) and aneuploidy (p = 0.036). Only 4 tumors showed microsatellite instability, 3 of which had a normal hTERT gene copy number. The data indicated that the increased copy number of the hTERT gene in colorectal carcinoma was a result of genomic instability with no obvious consequence for telomerase activity levels.

Telomere length maintenance, in the vast majority of cases executed by telomerase, is a prerequisite for long-term proliferation. Most malignant tumours, including lymphomas, are telomerase-positive and this activity is a potential target for future therapeutic interventions since inhibition of telomerase has been shown to result in telomere shortening and cell death in vitro. One prerequisite for the suitability of anti-telomerase drugs in treating cancer is that tumours exhibit shortened telomeres compared to telomerase-positive stem cells. A scenario is envisioned where the tumour burden is reduced using conventional therapy whereafter remaining tumour cells are treated with telomerase inhibitors. In evaluating the realism of such an approach it is essential to know the effects on telomere status by traditional therapeutic regimens. We have studied the telomere lengths in 47 diagnostic lymphomas and a significant telomere shortening was observed compared to benign lymphoid tissues. In addition, telomere length and telomerase activity were studied in consecutive samples from patients with relapsing non-Hodgkin's lymphomas. Shortened, unchanged and elongated telomere lengths were observed in the relapse samples. The telomere length alterations found in the relapsing lymphomas appeared to be independent of telomerase and rather represented clonal selection random at the telomere length level. These data indicate that anti-telomerase therapy would be suitable in only a fraction of malignant lymphomas.

CONTEXT: Tryptophan hydroxylase is the rate-limiting enzyme in the serotonin (5-HT) biosynthetic pathway responsible for the regulation of serotonin levels. Tryptophan hydroxylase 2 (TPH2) was found to be solely expressed in the brain and therefore considered an important susceptibility gene in psychiatric disorders.

OBJECTIVE: To determine the role of the brain-specific TPH2 gene in unipolar (UP) disorder and bipolar (BP) disorder in a northern Swedish, isolated population.

DESIGN: HapMap-based haplotype-tagging single nucleotide polymorphism (htSNP) patient-control association study.

SETTING: A northern Swedish, isolated population.

PARTICIPANTS: One hundred thirty-five unrelated patients with UP disorder, 182 unrelated patients with BP disorder, and 364 unrelated control individuals.

RESULTS: Significant allelic association was identified in our UP disorder association sample for an htSNP located in the 5' promoter region (rs11178997; P = .001). Haplotype analysis supported this significant result by the presence of a protective factor on hapblock 2 (P(specific) = .002). In the BP disorder association sample, single-marker association identified a significant htSNP in the upstream regulatory region (rs4131348; P = .004). Moreover, haplotype analysis in the BP disorder sample showed that the same htSNPs from hapblock 2 associated with UP disorder were also significantly associated with BP disorder (P(specific) = .002).

CONCLUSIONS: Haplotype-based analysis of TPH2 in patients with UP and BP disorder and controls from northern Swedish descent provides preliminary evidence for protective association in both disorders and thus supports a central role for TPH2 in the pathogenesis of affective disorders.

Most genetic association studies in bipolar disorder have focussed on genes involved in major neurotransmitter systems or brain development. Functional polymorphisms in the serotonin transporter (5-HTTLPR), catechol-O-methyltransferase (Val158Met) and dopamine D3 receptor (Ser9Gly) genes have all been associated with bipolar disorder. We aimed at investigating whether these functional variants contribute to the genetic etiology of bipolar disorder in a northern Swedish isolated population. Moreover, we wanted to gain information about the synergistic contribution of these functional variants. Neither of these functional polymorphisms was associated with bipolar disorder in the northern Swedish patient-control sample nor did we find evidence of gene-gene interaction. Together, our data suggest that these functional variants are not involved in the etiology of bipolar disorder in the northern Swedish population nor did gene-gene interaction analysis support a central role of these variants in bipolar disorder.

From a number of genome-wide association studies it was shown that de novo and/or rare copy number variants (CNVs) are found at an increased frequency in neuropsychiatric diseases. In this study we examined the prevalence of CNVs in six genomic regions (1q21.1, 2p16.3, 3q29, 15q11.2, 15q13.3, and 16p11.2) previously implicated in neuropsychiatric diseases. Hereto, a cohort of four neuropsychiatric disorders (schizophrenia, bipolar disorder, major depressive disorder, and intellectual disability) and control individuals from three different populations was used in combination with Multilpex Amplicon Quantifiaction (MAQ) assays, capable of high resolution (kb range) and custom-tailored CNV detection. Our results confirm the etiological candidacy of the six selected CNV regions for neuropsychiatric diseases. It is possible that CNVs in these regions can result in disturbed brain development and in this way lead to an increased susceptibility for different neuropsychiatric disorders, dependent on additional genetic and environmental factors. Our results also suggest that the neurodevelopmental component is larger in the etiology of schizophrenia and intellectual disability than in mood disorders. Finally, our data suggest that deletions are in general more pathogenic than duplications. Given the high frequency of the examined CNVs (12%) in patients of different neuropsychiatric disorders, screening of large cohorts with an affordable and feasible method like the MAQ assays used in this study is likely to result in important progress in unraveling the genetic factors leading to an increased susceptibility for several psychiatric disorders.

The GWAS-based association of CACNA1C with bipolar disorder (BPD) is one of the strongest genetic findings to date. CACNA1C belongs to the family of CACN genes encoding voltage-dependent calcium channels (VDCCs). VDCCs are involved in brain circuits and cognitive processes implicated in BPD and schizophrenia (SZ). Recently, it was shown that rare copy number variations (CNVs) are found at an increased frequency in SZ and to a lesser extent also in BPD, suggesting the involvement of CNVs in the causation of these diseases. We hypothesize that CNVs in CACN genes can influence the susceptibility to BPD, SZ, and/or schizoaffective disorder (SZA). A search for CNVs in eight CACN genes in a patient-control sample of European decent was performed. A total of 709 BP patients, 645 SZ patients, 189 SZA patients, and 1,470 control individuals were screened using the Multiplex Amplicon Quantification (MAQ) method. We found a rare, partial deletion of 35.7?kb in CACNA2D4 in two unrelated late onset bipolar I patients and in one control individual. All three deletions shared the same breakpoints removing exons 1726 of CACNA2D4, comprising part of the CACHE domain. Based on the data we cannot claim causality to BPD of the identified CACNA2D4 deletion but nevertheless this deletion can be important in unraveling the underlying processes leading to psychiatric diseases in general and BPD in particular.

Corticotropin-releasing factor-binding protein (CRF-BP) regulates the availability of free CRF and is a functional candidate gene for affective disorders. Previous research showed an association between polymorphisms in the CRF-BP gene and recurrent major depression (MDD) in a Swedish sample. The purpose of the current study was to re-evaluate the previous findings in an extended Swedish sample and in an independent Belgian sample of patients with recurrent MDD and in control samples. In total, 317 patients and 696 control individuals were included. Five single nucleotide polymorphisms (SNPs) and a deletion polymorphism in the CRF-BP gene were genotyped and the haplotype block structure of the gene was assessed. In the extended Swedish population, there was a trend towards an association between two SNPs and MDD. The subsequent gender analysis showed significant associations of three SNPs (CRF-BPs2 T; CRF-BPs11 T and CRF-BPs12 C) and haplotype G_T_C_T_C with MDD in Swedish males. However, these findings did not withstand correction for multiple testing and there were no significant SNP or haplotype associations in the Belgian MDD sample. In conclusion, this study does not provide confirmatory evidence for a role of the CRF-BP gene in the vulnerability for MDD in general. The association between genetic CRF-BP variants and MDD may be sexually dimorphic, but this issue requires further investigation in a larger sample.

Corticotropin-releasing factor-binding protein regulates the availability of free corticotropin-releasing factor and is a functional candidate gene for affective disorders. The aim of this study was to examine the association between polymorphisms in CRF-BP gene and bipolar disorder in an isolated Swedish population. One hundred and eighty-two patients with bipolar I disorder and 333 controls from Northern Sweden were included in the study. Five single nucleotide polymorphisms and a deletion polymorphism in the CRF-BP gene were genotyped. The haplotype block structure of the gene was considered and the expectation maximization algorithm was adopted to estimate the haplotype frequencies. As a result, there were no significant associations of the different polymorphisms in the CRF-BP gene with bipolar disorder. In conclusion, this study in an isolated Swedish population does not support a role for the CRF-BP gene in the vulnerability for bipolar disorder.

OBJECTIVE: An interaction between predisposing genes and environmental stressors is thought to underlie the neurodevelopmental disorder schizophrenia. In a targeted gene screening, we previously found that the minor allele of the single nucleotide polymorphism (SNP) rs6336 in the neurotrophic tyrosine kinase receptor 1 (NTRK1/TRKA) gene is associated with schizophrenia as a risk factor.

METHODS: We genotyped the TRKA SNP in a total of eight independent Caucasian schizophrenia case-control groups.

RESULT: Remarkably, although in five of the groups a higher frequency of the risk allele was indeed found in the patients compared with the controls, in the three other groups the SNP acted as a protective factor.

CONCLUSION: An intriguing possibility is that this dual character of the TRKA SNP is caused by its interaction with endophenotypic and/or epistatic factors.

Dysregulation of the hypothalamic-pituitary-adrenal axis, one of the stress-response systems, is one of the key neurobiological features of major depression (MDD). Data supporting the notion that glucocorticoid-mediated feedback inhibition is impaired in MDD come from a multitude of studies demonstrating nonsuppression of cortisol secretion following administration of the synthetic glucocorticoid dexamethasone. We examined whether genetic variations in the glucocorticoid receptor gene (Nuclear Receptor Subfamily 3, Group C, Member 1; NR3C1) could be associated with increased susceptibility for MDD using a whole gene-based association analysis of single nucleotide polymorphisms (SNPs). Four SNPs were identified in NR3C1 and genotyped in two well-diagnosed samples of patients with MDD ascertained in Belgium and northern Sweden, and matched control samples. In total, 314 MDD patients and 354 control individuals were included in the study. In the Belgian sample, we observed significant allele (p=0.02) and genotype (p=0.02) association with an SNP in the promoter region (NR3C1-1); in the Swedish sample, we observed significant allele (p=0.02) and genotype (p=0.02) association with the R23K SNP. The haplotype association studies showed modest evidence for an involvement of the 5' region of the NR3C1 gene in the genetic vulnerability for MDD. This study suggests that polymorphisms in the 5' region of the NR3C1 gene may play a role in the genetic vulnerability for MDD.

Telomere length shortens with cellular division, and leukocyte telomere length is used as a marker for systemic telomere length. The hippocampus hosts adult neurogenesis and is an important structure for episodic memory, and carriers of the apolipoprotein E ε4 allele exhibit higher hippocampal atrophy rates and differing telomere dynamics compared with non-carriers. The authors investigated whether leukocyte telomere length was associated with hippocampal volume in 57 cognitively intact subjects (29 ε3/ε3 carriers; 28 ε4 carriers) aged 49-79 yr. Leukocyte telomere length correlated inversely with left (r(s) = -0.465; p = 0.011), right (r(s) = -0.414; p = 0.025), and total hippocampus volume (r(s) = -0.519; p = 0.004) among APOE ε3/ε3 carriers, but not among ε4 carriers. However, the ε4 carriers fit with the general correlation pattern exhibited by the ε3/ε3 carriers, as ε4 carriers on average had longer telomeres and smaller hippocampi compared with ε3/ε3 carriers. The relationship observed can be interpreted as long telomeres representing a history of relatively low cellular proliferation, reflected in smaller hippocampal volumes. The results support the potential of leukocyte telomere length being used as a biomarker for tapping functional and structural processes of the aging brain.

Both leukocyte telomere length and the apolipoprotein epsilon4 allele have been associated with mortality, cardiovascular disease, cognition, and dementia. The authors investigated whether leukocyte telomere length was associated with APOE genotype or cognitive abilities in the context of APOE genotype. The setting for this cross-sectional study was 427 nondemented individuals aged 41-81 yr. The authors found that epsilon4 carriers overall exhibited significantly longer telomeres compared with non-carriers (difference of 268 bp, p = 0.001). This difference was greatest at the lower limit of the age span and nonsignificant at the upper limit, which translated into a significantly higher telomere attrition rate (p = 0.049) among epsilon4 carriers (37 bp/years) compared with non-carriers (21 bp/year). Further, longer telomeres among epsilon4 carriers significantly predicted worse performance on episodic memory tasks. No significant associations were found on tasks tapping semantic and visuospatial ability, or among epsilon3/epsilon3 carriers. In conclusion, APOE epsilon4 carriers had longer telomeres compared with non-carriers, but higher rate of attrition. Among them, longer telomeres predicted worse performance on episodic memory tasks. These observations suggest that the epsilon4 allele is associated with abnormal cell turnover of functional and possibly clinical significance.

Background: leukocyte telomere length (TL) is considered a marker of biological aging. Several studies have investigated the link between leukocyte TL and aging-associated functional attributes of the brain, but no prior study has investigated whether TL can be linked to brain atrophy and white matter hyperintensities (WMHs); two prominent structural manifestations of brain aging. Methods: we investigated whether leukocyte TL was related to brain atrophy and WMHs in a sample of 102 non-demented individuals aged 64-75 years. Results: shorter TL was related to greater degree of subcortical atrophy (beta = -0.217, P = 0.034), but not to cortical atrophy. Furthermore, TL was 371 bp shorter (P = 0.041) in participants exhibiting subcortical WMHs, and 552 bp shorter (P = 0.009) in older participants exhibiting periventricular WMHs. Conclusion: this study provides the first evidence of leukocyte TL being associated with cerebral subcortical atrophy and WMHs, lending further support to the concept of TL as a marker of biological aging, and in particular that of the aging brain.

Background: The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in stress regulation, and leukocyte telomere length (TL) has been suggested to represent a cumulative measure of stress. Depression is intimately related with stress and frequently exhibits a dysregulated HPA axis. We aimed to study the relationships between TL and biological and psychological facets of stress in recurrent major depressive disorder and controls.

Methods: Leukocyte TL was measured in 91 subjects with recurrent major depressive disorder and 451 control subjects. Stress was assessed from both a biological perspective, by assessing HPA axis function with a weight-adjusted very-low-dose dexamethasone suppression test (DST), and a psychological perspective, with self-report questionnaires.

Results: TL was shorter among patients compared with control subjects (277 base pairs, p = .001). Overall, short TL was associated with a hypocortisolemic state (low post-DST cortisol and high percentage of cortisol reduction after the DST) among both patients and control subjects but more pronounced among patients. This state, which was overrepresented among patients, was characterized by high familial loading of affective disorders among patients (p = .001) and high C-reactive protein levels among control subjects (p = .040). TL was also inversely associated with stress measured with the Perceived Stress Questionnaire (r_s = −.258, p = .003).

Conclusions: Short TL is associated with depression and hypocortisolism. Because hypocortisolism has been shown to develop from chronic stress exposure, our findings corroborate the concept of TL as a cumulative measure of stress and provide novel insights into the detrimental role of stress in depressive illness and the general population.