Objective: To evaluate whether apathy is associated with specific motor and non-motor features in patients with Parkinson’s disease.

Background: In a previous clinical cohort study we have demonstrated that cognitive strategies are less efficient in PD patients with apathy than in those without apathy, suggesting that apathy might be an early expression of dysexecutive syndrome due to impaired fronto-striatal activation.

Methods: This prospective study involved 71 patients enrolled in two Movement Disorders Centers (USA, Italy). Based on their score at the Apathy Evaluation Scale (AES), they were classified in two groups: PD with apathy (PD-A, n=35) and PD without apathy (PD-NA, n=36). Patients were evaluated with: Hamilton Depression Rating Scale-17 items (HAMD), the Unified Parkinson’s disease Rating Scale (UPDRS) and the Hoehn and Yahr staging system (H&Y), the Mini Mental State Examination (MMSE), the Frontal Assessment Battery (FAB) and were questioned about the presence/absence of REM sleep behavior disorder (RBD) and freezing of gait (FOG).

Results: PD-A and PD-NA groups did not differ in age, disease duration and treatment. The presence of apathy positively correlated with bradykinesia (R= 0.40, p<0.001), axial involvement (R=0.41, p<0.001), hypomimia (R=0.40, p<0.001); higher UPRDS motor score (R=0.37, p=0.002); FOG (R=0.55, p<0.001) and RBD (R=0.42, p<0.001). We also observed a weak correlation between apathy and the rigid phenotype at onset (R=0.25, p=0.0031). Apathy negatively correlated with FAB score (R=0.56, p<0.001). Finally, the right side of the body was predominantly involved in PD patients with apathy (R=0.40, p=0.001).

Conclusions: In PD patients with apathy, we found more severe rigidity, predominant axial and mask involvement, more frequent and severe FOG, more severe motor global impairment, and a higher rate of non-motor symptoms, specifically more severe executive deficits and frequent RBD. Furthermore, the right side of the body was predominantly involved in PD patients with apathy, suggesting a specific impairment of the left fronto-striatal circuitry in PD patients with apathy. Apathy seems to define a specific subtype of PD with more pronounced deficits of the auto-activation system, inhibiting spontaneous activation of mental processing for cognitive and actions.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/apathy-phenotype-in-parkinsons-disease-motor-and-non-motor-features/