Effects of depression and Parkinson's disease on cognitive functioning.

This study compared the performance of Parkinson's disease (PD) patients with and without depression, patients with depression alone, and normal control subjects on a cognitive screening instrument, the Mattis Dementia Rating Scale (DRS) to evaluate the influences of depression and Parkinson's disease on cognition. PD affects overall level of cognitive functioning and, to a lesser extent, DRS Initiation/Perseveration, Construction, and Attention. Diminished memory was primarily related to depression. Treatment of depression may ameliorate aspects of cognitive dysfunction in the PD patient with depression.