Age-Dependent Functional Decline and Recovery Patterns After Dementia Diagnosis in the Oldest-Old

BackgroundDementia prevalence and incidence rise sharply among the oldest-old (≥85 years), yet whether age-at-diagnosis shapes functional trajectories remains unclear. Understanding age-specific patterns is critical for tailoring care strategies.ObjectivesTo determine whether age at dementia diagnosis influences patterns of functional decline and recovery, and to identify the functional domains driving age-specific trajectories.MethodsUsing Manitoba Follow-up Study data, participants were grouped by age at dementia diagnosis (<85, 85-89, ≥90) or no dementia. We tracked Basic Activities of Daily Living (BADLs), Instrucmental Activities of Daily Living (IADLs), and SF-36 Physical/Mental scores. Generalized additive mixed models and mixed-effects random forest analyses assessed trajectories, dependence, and recovery.ResultsAge at diagnosis showed differences in trajectories. The ≥85 group showed steep post-diagnosis decline; the <85 group declined more steadily. Complex tasks (e.g., cutting toenail) were most impaired. Recovery occurred, particularly in IADLs and in the ≥90 group.ConclusionsAge at dementia diagnosis showed meaningful differences in functional decline and recovery, supporting age-specific care strategies.