What does the Dementia Rating Scale-2 measure? The relationship of neuropsychological measures to DRS-2 total and subscale scores in non-demented individuals with Parkinson's disease

Objective The Dementia Rating Scale-2 (DRS-2) is recommended for assessing global cognition in Parkinson's disease (PD) by the Movement Disorder Society. However, empirical evidence is limited regarding the degree to which the DRS-2 corresponds to traditional neurocognitive domains (i.e., construct validity) in PD. Thus, this study aims to determine the construct validity of the DRS-2 in a non-demented sample of PD patients. Method Patients with PD (n = 359; mean age = 64.50 +/- 8.53, education = 14.97 +/- 2.73, disease duration = 8.48 +/- 4.87, UPDRS Part III motor scale scores = 25.23 +/- 10.17) completed the DRS-2 as part of a comprehensive neuropsychological assessment consisting of attention/working memory, executive function, language, delayed recall, and visuoperceptual-spatial skills.Bootstrapped bias-corrected Spearman rho's correlations andhierarchical linear regressions were performed to examine construct validity of DRS-2 total and subscale scores. Results Speeded measures of set-shifting, rapid word generation to letter and semantic cues, and simple visuoperceptual skills largely accounted for variance in DRS-2 total scores. Most DRS-2 subscale scores showed weak relationships with theoretically related neuropsychological measures. Conclusions DRS-2 total scores reflect impairment across a range of cognitive domains (i.e., executive, language, and visuoperception), while DRS-2 subscale scores have limited construct validity. Together, the DRS-2 does not appear to have utility beyond screening for global cognition in PD.