Brain volume changes in Parkinson's disease and their relationship with cognitive and behavioural abnormalities

Cognitive and behavioral abnormalities are frequent in Parkinson's disease (PD) but their anatomical correlates are still uncertain. We assessed a cohort of 59 PD patients with and without impulse control disorders (PD-ICDs and PD-CNTR) with magnetic resonance imaging and a comprehensive neuropsychological battery. Thirty-five PD patients presented ICDs according to DSM-IV criteria and Minnesota Impulsive Disorders Interview. We found areas of significant brain atrophy in the middle and superior frontal gyrus in the whole cohort of 59 PD patients vs. healthy controls but there were no morphometric changes in PD-ICDs vs. PD-CNTR. This was consistent with cognitive findings of relatively preserved function in PD-ICDs with the exception for slower performance in the Trail Making Test B-A suggesting difficulties to maintain goal-directed tasks and suppress irrelevant responses. Voxel Based Morphometric regression analysis (VBM) carried out using TMTB-A as independent factor showed a negative gray matter correlation between high TMTB-A scores and left middle frontal cortex, right posterior cingulate area, anterior cingulate and supplementary motor area bilaterally. Our results suggest that PD is characterized by an overall loss of gray matter in pre-frontal regions. However, the contribution of these changes to the development of ICDs is marginal.