Development and validation of the geriatric apathy scale: Examining multi-dimensional apathy profiles in a neurodegenerative population with cultural considerations

BACKGROUND: Apathy is a common motivational deficit in neurodegenerative diseases, but lacks a culturally sensitive tool accounting for ethnic Chinese culture's impact on motivation initiation. This study developed and validated the Geriatric Apathy Scale (GAS), comprehensively incorporating cultural nuances, setting diagnostic cutoffs, and examining apathy's multi-dimensional aspects in a neurodegenerative cohort. METHODS: The 16-item GAS was developed by considering ethnic Chinese cultural characteristics and conducting a literature review. The study involved 296 participants, comprising 113 with Parkinson's disease (PD), 66 with Alzheimer's disease (AD), and 117 healthy controls (HC). All participants completed the GAS, Apathy Evaluation Scale (AES), Geriatric Depression Scale (GDS-15), Mini-Mental State Examination, and Activities of Daily Living (ADLs). RESULTS: The GAS showed good internal consistency (r = 0.862) and test-retest reliability (r = 0.767). It correlated moderately with the AES (r = 0.639, p < .001), weakly with GDS-15 (r = 0.166, p < .01), and negatively with ADLs (r = -1.19, p < .05). Clinical diagnosis cutoff scores were identified at 15.5 for PD (sensitivity: 0.789; specificity: 0.693) and 12.5 for AD (sensitivity: 0.821; specificity: 0.632). Noteworthy disparities were observed in the Cognition and Social Motivation dimension, with elevated severity in both PD and AD compared to HC (p < .01). Interestingly, within-group comparisons revealed greater apathy severity in the Cognition and Social Motivation dimension for PD (p < .001) and AD (p = .001) versus Emotional Response and Expression and Spontaneous Behavioral Activation. CONCLUSIONS: The GAS, a psychometrically validated scale, assesses apathy in neurodegenerative populations, accounting for ethnic Chinese culture's influence. It establishes clinical cutoff points and explores the multidimensional nature of apathy.