Dementia in Parkinson's disease: Usefulness of the pill questionnaire

The Level I algorithm for the diagnosis of dementia associated with Parkinson's disease (PD‐D) recommended by the Movement Disorder Society task force includes a Pill Questionnaire to determine the impact of cognitive decline on daily activities. The objective of this study was to test the performance of the Pill Questionnaire as a screening tool for the detection of dementia (all‐cause) in patients with PD and to test the performance of another functional scale substituting the Pill Questionnaire for the diagnosis of “probable PD‐D” (pPD‐D). Data were collected from 529 patients who had PD in Hoehn and Yahr stages 1 through 5. The measures used include the Scales for Outcomes in PD‐Motor (SCOPA‐Motor), scales for psychiatric complications, the Mini Mental State Examination, the Clinical Impression of Severity Index, and the Pill Questionnaire. The SCOPA‐Motor functional subscale score was categorized as “impact” or “no impact” of PD on daily activities. According to clinical judgment, 13.3% of patients had dementia. For detecting dementia, the Pill Questionnaire had 89% accuracy, although its positive predictive value was 55%. Performance was worse with the categorized SCOPA‐Motor subscale. According to the Movement Disorder Society task force criterion, 85 patients (16.1%) had pPD‐D. When the Pill Questionnaire was substituted by the categorized SCOPA‐Motor subscale, the modified algorithm showed sensitivity, specificity, and accuracy indexes over 90% but had positive predictive value of 66% for pPD‐D diagnosis. Although the Pill Questionnaire demonstrated acceptable basic properties as a screening tool for dementia, its positive predictive value was low. The SCOPA‐Motor subscale cannot be proposed as a substitute for the Pill Questionnaire. © 2013 International Parkinson and Movement Disorder Society