In older adults who survived stroke, incident stroke is associated with acute and accelerated long-term cognitive decline, according to study findings published in JAMA Network Open.

Researchers explored the effects of a first stroke on cognitive function in community-dwelling older adults without a history or stroke or dementia. Based on whether or not they experienced an interval stroke during follow-up, participants were classified into stroke and no-stroke groups. Data were harmonized and pooled from 14 population-based cohort studies that were conducted across 11 countries between 1993 and 2019, involved at least 2 follow-up neuropsychological evaluations, and collected data on interval stroke. The primary outcome was global cognition, which was defined as the standardized mean of 4 cognitive domains (ie, language, memory, processing speed, and executive function). To estimate the trajectories of cognitive function poststroke relative to a stroke-free cognitive trajectory, linear mixed-effects models were used.

A total of 20,860 participants (mean age, 72.9; women, 58.8%; White, 78.7%; mean years of education, 10.1) were included in the study, 1041 (5.0%) of whom experienced a first incident stroke at a mean of 4.55 years after study entry at a mean age of 79.5. Follow-up durations ranged from 3 to 17 (mean, 7.51) years.

Targeting modifiable vascular risk factors at an early stage may reduce the risk of stroke but also subsequent risk of stroke-related cognitive decline and cognitive impairment.

Incident stroke was associated with a significant acute decline in global cognition (-0.251 SD; 95% CI, -0.332 to -0.170 SD), as well as accelerated decline in global cognition (-0.038 SD per year; 95% CI, -0.057 to -0.019 SD).

The mean rate of decline without a previous stroke in all individuals was -0.049 SD per year (95% CI, -0.051 to -0.047 SD) in global cognition.

The acute outcome of stroke on cognitive function was substantial across all cognitive domains (range in effect sizes, -0.17 to -0.22 SD), as well as for the Mini-Mental State Examination (MMSE; -0.36 SD). Long-term outcomes of stroke on slope, however, were only significant for language, processing speed, and executive function, not memory or the MMSE. The difference in slope post-stroke was smallest for language (-0.020 SD per year; 95% CI, -0.039 to -0.001 SD per year) and largest for processing speed (-0.055 SD per year; 95% CI, -0.076 to -0.035 SD per year).

Factors associated with change in poststroke cognitive trajectory included age and acute outcome (0.013 SD; 95% CI, 0.002-0.023 SD). Older stroke survivors (aged ≥72 vs <72) experienced less acute decline, but exhibited lower cognitive levels at baseline and significantly faster decline without stroke (-0.063 SD per year vs -0.034 SD per year).

Study limitations include potential recall bias, varying follow-up durations across cohorts, unmeasured confounding variables, and high attrition rates.

“Targeting modifiable vascular risk factors at an early stage may reduce the risk

of stroke but also subsequent risk of stroke-related cognitive decline and cognitive impairment,” the researchers concluded.