ICARUS study: prevalence and clinical features of impulse control disorders in Parkinson's disease.

Background: Impulse control disorders/other compulsive behaviours ('ICD behaviours') occur in Parkinson's disease (PD), but prospective studies are scarce, and prevalence and clinical characteristics of patients are insufficiently defined.

Objectives: To assess the presence of ICD behaviours over a 2-year period, and evaluate patients' clinical characteristics.

Methods: A prospective, non-interventional, multicentre study (ICARUS (Impulse Control disorders And the association of neuRopsychiatric symptoms, cognition and qUality of life in ParkinSon disease); SP0990) in treated Italian PD outpatients. Study visits: baseline, year 1, year 2. Surrogate primary variable: presence of ICD behaviours and five ICD subtypes assessed by modified Minnesota Impulsive Disorder Interview (mMIDI).

Results: 1069/1095 (97.6%) patients comprised the Full Analysis Set. Point prevalence of ICD behaviours (mMIDI; primary analysis) was stable across visits: 28.6% (306/1069) at baseline, 29.3% (292/995) at year 1, 26.5% (245/925) at year 2. The most prevalent subtype was compulsive eating, followed by punding, compulsive sexual behaviour, gambling and buying disorder. Patients who were ICD positive at baseline were more likely to be male, younger, younger at PD onset, have longer disease duration, more severe non-motor symptoms (including mood and sexual function), depressive symptoms, sleep impairment and poorer PD-related quality of life. However, they did not differ from the ICD-negative patients in their severity of PD functional disability, motor performance and cognitive function.

Conclusions: Prevalence of ICD behaviours was relatively stable across the 2-year observational period. ICD-positive patients had more severe depression, poorer sleep quality and reduced quality of life.