Apathy and Depression Impact on Cognitive Decline: Neuropsychological Specificities across Neurodegenerative Diseases

Apathy is a common symptom across neurodegenerative diseases with origins still debated. "Vascular apathy hypothesis" by Van der Mast suggests vascular pathologies precede apathy. Other evidence points to dysfunction in dopamine pathways, driving apathy by impairing goal-directed behaviour. The impact of apathy on cognitive decline and autonomy, particularly with coexisting depression, remains unclear. This cross-sectional study aimed to (1) characterize apathy in vascular dementia, Parkinson's disease (PD), and Mild Cognitive Impairment-Alzheimer Disease (MCI-AD) regarding incidence, severity, and cognitive specificity; (2) differentiate effects of apathy and depression on cognitive impairment and daily autonomy (Activities of Daily Living [ADL]).

Fifty-three patients underwent neuropsychological testing and completed the Geriatric Depression Scale, Starkstein's Apathy Scale, and ADL questionnaire at a clinical neuropsychology outpatient setting in Milan.

56% patients had cardiovascular pathologies, 20% had PD, and 22% had MCI-AD. Neither prevalence nor severity of apathy or depression differed significantly across diseases. Hierarchical regression showed apathy predicted language initiative controlling for depression (R2 = 0.249; F(2) = 4.144; p = .028), and inversely correlated with working memory, language and frontal functioning, while depression predicted autonomy controlling for apathy (R2 = 0.234; F (2) = 3.821; p = .036).

Apathy is prevalent across different neurodegenerative diseases and exacerbates specific cognitive impairments. Distinguishing vascular apathy from other forms remains challenging.