PDD-Short Screen: a brief cognitive test for screening dementia in Parkinson's disease.

The diagnosis of Parkinson's disease with dementia (PDD) is currently based on clinical criteria (DSM-IV, MDS-Task Force). In daily practice and research studies, these criteria still depend on the subjective impression of the examiner. Brief screening tests (BST) are helpful in identifying patients with PD with dementia, which can be difficult in patients with advanced PD. We aimed to develop a BST for PD, the PDD-Short Screen (PDD-SS), to accurately and quickly screen for PDD. In this prospective study, 70 patients with nondemented (age 73.8 +/- 4.4) and 32 demented (age 73.8 +/- 4.4) PD regularly attending a Movement Disorders Clinic were included. Diagnosis of dementia was based on DSM-IV criteria, CDR score >or=1, and PD-CRS total score <or=64. The PDD-SS, Mattis Dementia Rating Scale (MDRS), and Mini-Mental State Examination (MMSE) were administered to all participants. Validity, reliability, and discriminative power of the PDD-SS were examined. The final version of the scale included the items immediate and delayed verbal memory, clock drawing, alternating verbal fluency, and a questionnaire covering cognitive and psychiatric (hallucinations, apathy) symptoms common in PDD. A cutoff score <or=11 on the PDD-SS yielded high sensitivity (89.8%) and specificity (88.5%) for diagnosing PDD. The MDRS displayed similar accuracy, but the PDD-SS administration time was significantly shorter (4.8-6.9 vs. 17.5-25.2 minutes). Diagnosis of dementia using the PDD-SS was not influenced by age, education, or motor function. The PDD-SS appears as the first BST for diagnosing PDD, displays an excellent diagnostic accuracy, and takes 5 to 7 minutes to be administered.