Apathy, Beta-amyloid Burden and Cognitive Decline in Parkinson’s Disease Patients

Introduction Apathy is a common non-motor symptom in Parkinson’s disease (PD), and its presence constitutes a risk factor for the development of cognitive impairment in this population (Burchill et al. Lancet Reg Health Eur 2024; 39:100870). β-amyloidopathy has been associated to shorter interval to dementia in PD and may also be a determinant of apathy. Objectives We aimed to investigate β-amyloid burden in non-demented PD patients based on the presence or absence of apathy, and how both factors influence the rate of progression to mild cognitive impairment or dementia over a 3-year period. Methods Forty-eight PD patients underwent clinical and comprehensive neuropsychological evaluation, as well as [18F]-flutemetamol positron emission tomography. They were classified as apathetic (n=22) or non-apathetic (n=26) based on their score on the Starkstein Apathy Scale. Brain imaging analysis was conducted using the SPM software package. Results We found statistically significant differences in disease duration when comparing clinical and demographic variables. Upon neuropsychological evaluation, apathetic patients performed significantly worse in attention domain (Digit Span and Trail Making Test A), executive function (Stroop Word-Colour Test and Trail Making Test B) and verbal memory (CERAD Total Word Recall). At follow up, 47.4% of apathetic patients progressed to dementia or MCI, compared to 12% of non-apathetic patients (χ² = 6.81, p <0.05). Brain imaging analysis revealed higher β-amyloid deposition in several cortical areas in apathetic PD patients (adjusted for disease duration and global composite cognitive z-scores). Conclusions The presence of apathy in PD patients is associated with greater cortical β-amyloidopathy and indicates a higher conversion rate to a worse cognitive diagnosis within a 3-year period. Disclosure of Interest None Declared