Abstract Body: Introduction: Stroke is associated with acute and persistent cognitive decline. Little is known about how cognitive trajectories vary in younger (18-64 years old) and older (≥65 years old) stroke survivors, as prior studies largely focus on older stroke survivors. We leveraged a pooled longitudinal cohort, with pre-stroke measures of cognition, to compare post-stroke cognitive trajectories between older and younger stroke survivors.

Methods: This was an individual participant data meta-analysis of a pooled longitudinal cohort of 1,292 stroke survivors from the Atherosclerosis Risk in Communities, REasons for Geographic and Racial Differences in Stroke, and Framingham Offspring studies from 1971-2019. Participants ≥18 years old with incident stroke without pre-stroke dementia were included (197 younger participants, 1,095 older participants, 49.8% female, 44.3% Black). Trained cohort staff administered repeated cognitive assessments. The initial post-stroke global cognitive performance assessment occurred a median (IQR) of 0.8 (0.4-2.6) years after stroke in the younger and 0.6 (0.3-1.4) years after stroke in the older group. Segmented linear mixed effect models were used to evaluate the association between age groups (younger and older) or age as a continuous variable and decline in global cognitive performance, executive function, and memory after stroke. Outcomes were harmonized across cohorts.

Results: We found that older participants had a greater initial decline in cognition after stroke than younger participants (-1.69 points [95% CI, -2.82 to -0.55] greater for global cognitive performance; -1.05 points [95% CI, -1.92 to -0.17] greater for memory; and -3.72 points [95% CI, -5.23 to -2.21] greater for executive function). The rate of decline in cognition after stroke, compared to before stroke, was faster with older age for global cognitive performance (-0.18 points per year [95% CI, -0.36 to -0.01] faster in older compared to younger adults) and executive function (-0.16 [95% CI, -0.26 to -0.06] points per year for every 10 years of higher age) but not memory (-0.006 [95% CI, -0.15 to 0.14]).

Conclusion: Even after considering age-related differences in pre-stroke cognitive trajectories, older age is associated with greater initial declines in global cognitive performance, executive function and memory and faster declines in global cognitive performance and executive function after stroke.