Validity of the Cornell scale for depression in dementia in Parkinson's disease with and without cognitive impairment.

Valid tools are needed to assess depression across the spectrum of cognitive impairment in Parkinson's disease (PD). The validity of the Cornell scale for depression in dementia (CSDD) was tested in a PD sample with a range of cognitive impairment. Psychiatric diagnoses were established according to DSM-IV-TR. Receiver operating characteristic curves tested the discriminant validity of the CSDD compared to the clinical diagnoses of major and minor depression. The curve for symptomatic depression had an area under the curve of 0.82. For the cut-off score >or= 6, sensitivity was 0.83 and specificity was 0.73; for the cut-off score >or= 8, sensitivity was 0.75 and specificity was 0.82. There was no evidence for differential measurement with respect to cognitive impairment or any other demographic or clinical variables. This study suggests that the CSDD is a valid tool for identifying depressive disorders in patients with PD across a spectrum of cognitive impairment. (c) 2008 Movement Disorders Society.