The study adopted CFA to investigate the factorial structure and reduce the number of items of the Cognitive Dysfunction Questionnaire (CDQ; Vestergren, Rönnlund, Nyberg, & Nilsson, 2011). The analyses were based on data for a total of 1115 participants from population based samples (mean age: 63.0 ± 14.5 years, range: 25 - 95) randomly split into a refinement (n = 569) and a cross-validation (n = 546) sample. Equivalence of the measurement and structural portions of the refined model was demonstrated across the refinement and cross-validation samples. Among competing models the best fitting and parsimonious model had a hierarchical factor structure with five first-order and one second-order general factor. The final version of the CDQ consisted of 20 items in five domains (Procedural actions, Semantic word knowledge, Face recognition, Temporal orientation and Spatial navigation). Internal consistency reliabilities were adequate for the total scale and for the subscales. Multigroup CFAs were performed and the results indicate measurement invariance across age and sex up to the scalar level. Finally, higher levels of cognitive dysfunction as reflected by CDQ scores were observed with advancing age and with deficits in general cognitive functioning as reflected by scores on the Mini-Mental State Examination. In conclusion, adoption of the final version of the CDQ appears to be a way of measuring cognitive dysfunction without administering formal cognitive tests. Future studies should apply it among clinical groups to further test its usefulness.