Is a patient-administered depression rating scale valid for detecting cognitive deficits in patients with major depressive disorder?

Aims: Although cognitive deficits are a common and potentially debilitating feature of major depressive disorder (MDD), such subjective declines in cognitive function are seldom validated by objective methods as a clinical routine. The aim of this study was to validate the Taiwanese Depression Questionnaire (TDQ) for detecting cognitive deficits in a sample of drug-free patients with MDD. Methods: The subjects consisted of 40 well-characterized medication-free patients with MDD and 40 healthy controls. Clinical and neuropsychological assessments, including the Wisconsin Card Sorting Test, the Wechsler Memory Scale-Revised, the Continuous Performance Test, and the Finger-Tapping Test, were administered at the time of recruitment. Results: Factor analyses of the TDQ yielded three factors. Memory, attention and psychomotor performance were significantly poorer in patients with MDD. The performances of verbal and delayed memory of the Wechsler Memory Scale-Revised were correlated with the cognitive domains of the TDQ. Generalization of our results must be undertaken with caution considering the relatively small sample size, which could lead to increased β-error. Conclusion: Cognitive subdomains might be considered important for including in patient-administered questionnaires used to measure symptoms of MDD when developing a new scale.