Neuropsychological correlates of alexithyrnia in Parkinson's disease

There are recent reports that alexithymia may be associated with brain dysfunction involving frontal lobes or right hemisphere regions. However, little is known about the relationship between alexithymia and cognitive deficits in Parkinson's disease (PD). The authors investigated the neuropsychological correlates of alexithymia in a population of 70 nondemented PD patients and 70 controls. Alexithymia was screened using the 20-item version of the Toronto Alexithymia Scale (TAS-20). Standardized scales that measure verbal episodic memory, executive functions, abstract reasoning, and visual-spatial and language abilities were adopted. PD patients with alexithymia performed worse than both PD patients without alexithymia and controls with or without alexithymia on tasks requiring visual-spatial processing. Moreover, regression analyses showed that, in PD patients, but not in controls, poor performance on a constructional praxis task predicted high scores on the TAS-20 subscale, which assesses difficulty in identifying emotions. These data evidence an association between alexithymia and visual-spatial processing alterations in PD patients, supporting the view that the right hemisphere could be specifically involved in the modulation of some facets of alexithymia.