Abstract
OBJECTIVE: Depression in aging shows heterogeneous symptoms across cognitive, affective, and neurobiological domains. Traditional categorical diagnoses may not capture these complex patterns, prompting a shift toward dimensional or domain-based approaches. We examined whether the symptoms that bridge cognition and affect differ by age and explored their associations with brain structure. METHODS: Data from 756 young (≤45 years) and 1,230 older (≥65 years) adults from the Cambridge Centre for Ageing and Neuroscience were analyzed. Cognition was assessed using the Addenbrooke's Cognitive Examination-Revised, and depressive and anxiety symptoms were assessed using the Hospital Anxiety and Depression Scale. Graphical LASSO was used to construct cognitive-affective networks, testing for age-related differences in strength and bridging centrality measures. Building on these findings, we further examined the association between bridging symptoms, cognition, and gray matter volume (GMV). RESULTS: Symptom strength centrality was similar across age groups. However, significant age-related differences emerged in bridging symptoms. Specifically, the primary bridging symptom differed, with dysphoria in young adults and anhedonia in older adults. Follow-up analyses showed that cognition mediated the link between GMV and anhedonia, but not dysphoria, particularly in older adults. DISCUSSION: Cognitive-affective bridging symptoms differ with age, with anhedonia replacing dysphoria as the key bridge in older adults. This shift was linked to age-related differences in the relationship between GMV, cognition, and depressive symptoms. These results highlight the need to target different symptoms to alleviate cognitive-affective manifestations across the lifespan.