Parkinson's disease (PD) is a neurodegenerative disorder that is associated with a wide range of motor symptoms, cognitive deficits and behavioral disorders. Apathy and impulse control disorders (ICDs) are common in these patients and have been considered opposite ends of a reward and motivation disorders continuum.

To evaluate the association and impact of ICDs presence on apathy symptoms in PDs patients, considering the influence of other psychopathological symptoms on this association.

This is a cross-sectional, observational study in which 115 consecutive medicated PD patients without dementia (mean age 61.22±13.5 years; 63.5% men) were recruited. All the patients underwent a psychiatric and neurologic evaluation. Motor dysfunction was assessed with the Unified Parkinson's disease Rating Scale (UPDRS), ICDs were evaluated with the Minnesota Impulse Control Disorders Inventory (MIDI) and apathy with the Lille Apathy Scale (LARS). The Hamilton Depression scale (HAM-D). The State-Trait Anxiety Inventory (STAI-S) and Barrat Impulsivity Scale (BIS) were also administrated.

Twenty-seven (23.5%) patients showed an ICD. Patients with an ICD scored higher in apathy (P=0.012), trait anxiety (P=0.003) and impulsivity (P=0.008). There were no differences in depressive symptoms. In the linear regression analysis, TCI was associated with more severe apathy (b=4.20, t=2.15, P=0.034).

ICDs and apathy are frequent in PD. Although ICDs have been related with a hyperdopaminergic state and apathy with low dopamine levels, the observed frequent association suggests common etiopathological mechanisms.