Validation of the Unified Parkinson's Disease Rating Scale (UPDRS) section I as a screening and diagnostic instrument for apathy in patients with Parkinson's disease.

We examined the validity of the motivation/initiative item of the Unified Parkinson's Disease Rating Scale (UPDRS) section I as a screening and diagnostic measure for apathy in Parkinson's disease (PD). Fifty-eight patients with PD were evaluated with the UPDRS, the 14-item Apathy Scale (AS), and standardized rating scales of depression and cognitive impairment. Apathy was diagnosed using specific items of the AS together with proposed criteria for apathy. A score of 2 or more on the motivation/initiative item was adequate to screen for apathy, whereas a score of 4 had high diagnostic accuracy at the cost of unacceptable low sensitivity.