Marital dissolution and cognition: The mediating effect of β-amyloid neuropathology

Background Widowhood and divorce are extremely stressful life events and have been associated with high risk of dementia and cognitive impairment. However, the neurobiological mechanisms underlying how this risk is conferred requires further investigation. Alzheimer’s disease (AD) pathology, such as β-amyloid (Aβ), may explain influences of chronic stress, such as those seen in disruptive marital transitions, on declines in cognition. Therefore, we examined whether Aβ mediates associations between marital dissolution (through widowhood or divorce) and executive functioning (EF) and episodic memory (EM) performance in cognitively normal (CN) individuals. Methods Data from 543 CN participants from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) were analysed. Outcomes included marital status, Aβ PET tracer uptake, and composite EF and EM scores. Primary analyses assessed relationships between marital dissolution and Aβ pathology, and marital dissolution and cognitive performance, and explored whether Aβ mediated associations between the latter. Results Marriage dissolution was associated with increased Aβ burden (β= 0.56; 95% CI: 0.11 to 1.02; P = 0.015) and worse EM performance (β= –0.09; 95% CI: –0.15 to –0.03; P = 0.003). Level of Aβ neuropathology was also identified as a significant mediator for the relationship between marriage dissolution and EM (ACME= –0.007; P = 0.029). Conclusions Aβ pathology was identified as a potential neurobiological mediator for the impacts of chronic stress due to marital dissolution on poorer memory performance. This suggests that stressful life events, such as the dissolution of one’s marriage might exert a direct effect on AD proteinopathy, which may subsequently influence poor cognition.