Development of the Cognitive Dysfunction Questionnaire (CDQ) in a population based sample.

The study reports on the development of a questionnaire for assessment of adult cognitive dysfunction (CDQ). Participants in a population-based sample (65±15 years, N=370) responded to a 90-item pilot version covering multiple aspects of memory/cognition. Based on exploratory principal components analyses and correlations with criterion measures of cognitive functioning (MMSE, Block Design, semantic/episodic memory), 20 items loading on 6 components were selected for the final version of the questionnaire. Cronbach's α for the total score was 0.90. There was evidence of construct validity as judged by correlations between CDQ scores, objective cognitive measures, and a subjective memory measure (PRMQ). Discriminant validity was demonstrated by a low and non-significant correlation with depressive symptoms. Further evidence of construct validity was provided by correlations with age and educational attainment. In conclusion, the CDQ is promising as a self-rating screening tool for cognitive dysfunction, and will be the subject of further development and validation.