Validity of the dementia rating scale in assessing cognitive function in Parkinson's disease

Two studies examined the validity of the Dementia Rating Scale (DRS) as a m easure of cognitive functioning among patients with Parkinson's disease (PD ). The DRS accounted for more variation in the level of cognitive functioni ng of PD patients than either the Mini-Mental Status Examination or a batte ry of tests selected to assess specific cognitive deficits associated with PD. Further, DRS subtests displayed strong convergent and discriminant vali dity with a comprehensive Criterion Neuropsychology Battery. The DRS subtes ts appear to be valid measures of attention, perseveration, conceptualizati on, and memory among PD patients. However, the DRS-Construction subtest sho uld be supplemented with additional visuoconstructional items to provide a thorough screen of cognitive functioning in PD. Although about three-quarte rs of nondemented PD patients did not appear to have any specific cognitive deficits on the DRS, the remaining patients were impaired on the Construct ion or Initiation/Perseveration subtests of the DRS. In summary, the DRS is a valid mental status screening test of cognitive functioning for individu als with PD.