Investigating the structural neuroimaging signature of apathy in Parkinson's disease

Background: Apathy is a common syndrome in up to 70 % of people with Parkinson's disease (PD), and it tends to worsen as the disease progresses. It is an independent predictor of poor clinical outcomes and reduced quality of life in PD patients. Apathy is linked to lower adherence to treatment and has a significant impact on the emotional well-being of caregivers. Identifying the neural basis of PD-related apathy is vital for determining treatment targets and prognostic biomarkers. Objectives: To define the neuroanatomical basis of apathy in PD compared to controls. Methods: Cross-sectional study including 24 patients with PD and 25 controls. Participants underwent a comprehensive clinical assessment and a structural magnetic resonance imaging (MRI) protocol. Elastic Net regression models with clinical, demographic, volumetric, and cortical thickness data were used to identify key predictors of the apathy scale (AS) scores in both groups. Results: Significant neuroanatomical predictors of the AS scores were identified, with distinct predictors for PD patients and controls. The best predictor of AS scores in the PD group was the cortical thickness of the right temporal pole, while the best predictor in the control group was the volume of the mid-anterior corpus callosum. The models revealed differences in the predictors' strength and direction between groups. Conclusions: The study underscores the distinct neuroanatomical correlates of apathy in PD, offering insights into the condition's underlying mechanisms. This contributes to the broader understanding of PD-related apathy and highlights potential areas for therapeutic intervention.