Cognitive function in Parkinson's disease: Association with anxiety but not depression

To reexamine the relationships of depression, anxiety and cognitive impairment in Parkinson's disease (PD), 27 patients with idiopathic PD received two measures of depression, the State-Trait Anxiety Inventory, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Contrary to some earlier studies, measures of depression, even those that separated mood from somatic symptoms, were not correlated with any measure of cognitive performance. By contrast, measures of anxiety were significantly and negatively correlated with all RBANS indexes. Because anxiety and depression are partially overlapping psychiatric disorders, inconsistent reports concerning the relationship of depression and cognition in PD may have arisen because different studies included varying proportions of depressed patients who were also highly anxious.