Cognitive complaints in Parkinson's disease: its relationship with objective cognitive decline.

Cognitive complaint interviews (CCI) have been shown to be useful in the early detection of dementia in elderly people. Surprisingly, CCIs are rarely used in Parkinson's disease (PD), despite a six-fold higher risk of dementia than in healthy subjects. The present study sought to determine whether a structured CCI could detect cognitive decline in PD. A validated CCI was added to the usual clinical interview for 180 PD patients. Objective cognitive status was assessed by the Mattis dementia rating scale score. The CCIs ability to detect cognitive decline in PD patients was determined using a receiver operating characteristic (ROC) curve. 58 (32.22%) patients had a significant, subjective cognitive complaint (CCI score >3). Of these, 48.27% had objective cognitive decline. Objective cognitive decline was significantly more frequent in the patients with subjective cognitive complaint. However, the ROC curve for discriminating between patients with and without objective cognitive deficits as a function of their subjective cognitive complaint had low sensitivity (0.50, 95% CI: 0.36-0.64) and moderate specificity (0.74, 95% CI: 0.69-0.84). Logistic regression incorporating the main demographical and clinical variables showed that the CCI score's discriminant power was improved by adding age and the number of years in education to the predictive model. Objective cognitive decline and dementia are more frequent among PD patients reporting a cognitive complaint than among patients not reporting a complaint. However, the CCI does not enable more accurate screening for PD-associated dementia.