The Syndromal Validity and Nosological Position of Apathy in Parkinson's Disease

Although apathy is among the most frequent behavioral changes in Parkinson's disease (PD), its diagnosis is still problematic, and the overlap with depression and dementia poorly Studied. Aim of the study was validate specific criteria to diagnose apathy in PD, and to examine its association with subsyndromes of depression and dementia. A series of 164 patients with PD, 44 patients with primary depression and no PD, 23 patients with Alzheimer's disease, and 26 age-comparable healthy controls underwent a comprehensive psychiatric assessment that included a structured psychiatric interview and the Apathy Scale. A set of seven diagnostic criteria showed high sensitivity and specificity for clinically diagnosed apathy. Fifty-two of the 164 patients with PD (32%) met diagnostic criteria for apathy. Eighty-three percent of patients with apathy had comorbid depression and 56% had dementia. Only 5 of the 40 PD patients (13%) with neither depression nor dementia had apathy. We validated a set of standardized criteria for the diagnosis of apathy in PD. About one third of a series of patients attending a Movement Disorders Clinic showed apathy. Both depression and dementia were the most frequent comorbid conditions of apathy in PD. (C) 2009 Movement Disorder Society