The contribution of somatic symptoms to the diagnosis of depressive disorder in Parkinson's disease: a discriminant analytic approach.

This study assessed the sensitivity of individual depressive symptoms and their relative contribution to the diagnosis of depressive disorder in patients with Parkinson's disease. The Structured Clinical Interview for DSM-IV Depression and the Hamilton and Montgomery-Asberg depression rating scales (Ham-D, MADRS) were administered to 149 consecutive nondemented patients. The contribution of the individual items of these scales to the diagnosis of "depressive disorder" was calculated by discriminant analysis. The discriminant models based on the Ham-D and MADRS scores were both highly significant. Nonsomatic core symptoms of depression had the highest correlation coefficient. Somatic items had mostly low correlation coefficients, with the exception of reduced appetite and early morning wakening (late insomnia). Nonsomatic symptoms of depression appear to be the most important for distinguishing between depressed and nondepressed patients with Parkinson's disease, along with reduced appetite and early morning awakening.