Can we predict development of impulsive-compulsive behaviours in Parkinson's disease?

Objective To determine clinical and structural imaging predictors of impulsive-compulsive behaviour (ICB) in de novo Parkinson's disease (PD). Methods From a cohort of 1116 subjects from the Parkinson's Progression Marker Initiative database, we created a subcohort of 42 de novo PD without ICB at baseline with available 3T MRI and who developed ICB during follow-up. PD-ICB were matched for age, gender and disease duration to 42 patients with PD without ICB over follow-up (PD-no-ICB) and 42 healthy controls (HCs). Baseline demographic and clinical predictors of ICB were analysed. For the longitudinal neuroimaging analysis, we selected 27 patients with PD-ICB with available neuroimaging after ICB onset, who were matched with 32 PD-no-ICB and 35 HCs. Baseline and longitudinal structural differences were compared using voxel-based morphometry and voxel-based quantification. Results People who went on to develop ICB had more severe anxiety, worse autonomic and global cognitive functions and were more likely to have rapid eye movement sleep behaviour disorder. Logistic regression confirmed that worse autonomic and cognitive functions were predictors of ICB. We could not find any morphological feature on baseline MRI that predicted later onset of ICB. When comparing PD groups at follow-up, a small region of increased atrophy in the anterior limb of the left internal capsule adjacent to the head of the left caudate nucleus was found in PD-ICB, but not surviving correction for multiple comparisons. Conclusions Worse autonomic and cognitive functions predict development of ICB at the time of PD diagnosis. Structural imaging fails to identify morphological features associated with the development of ICB.