Abstract 31: Rate of Change in Memory Functioning Before and After Stroke Onset

Abstract

Introduction: Although memory impairment is both a predictor and a consequence of stroke, memory decline is common even in healthy elderly. We use a prospective cohort to describe the long-term trajectory of memory functioning before and after stroke and compare it with memory changes in stroke-free elderly. Hypotheses: Poor memory functioning in stroke survivors compared to stroke-free elderly reflects the combined effects of accelerated pre-stroke memory decline, a decrement of memory functioning at the time of stroke, and faster post-stroke declines. Methods: Participants age 50+ in the Health and Retirement Study (n=12,412) who were stroke-free at baseline were interviewed biennially for up to 10 years for onset of first self- or proxy-reported stroke (n=1,526). Segmented linear regression models were used to compare annual rates of change in memory functioning (expressed as z-scores based on a composite of immediate and delayed word list recall and proxy assessments) before and after stroke among three groups: 1,027 individuals who survived a stroke and participated in a subsequent cognitive assessment (stroke survivors); 499 individuals who died after stroke before the next cognitive assessment (stroke decedants); and 10,886 cohort members who remained stroke-free for the entire follow-up period. Models were adjusted for core demographics. Results: Before first stroke onset, individuals who later survived a stroke had lower memory functioning than those who remained stroke free throughout follow-up, but rate of memory decline was similar for the two groups (-0.034 points/year [95% CI: -0.04, -0.029] for stroke survivors vs. -0.028 points/year [-0.031, -0.025] for stroke free adults). Individuals who later died after stroke had significantly faster pre-stroke memory declines (-0.118 points/year; -0.155, -0.079). Among stroke survivors, memory declined an average of 0.157 points (-0.199, -0.116) at stroke onset, comparable to 5.6 years of age-related decline in stroke-free cohort members. In the years following stroke, rate of memory decline in stroke survivors accelerated only slightly compared to pre-stroke rate of decline, to -0.038 points/year (-0.048, -0.03). Conclusions: Although stroke induced large immediate decrements in memory, differences were apparent years before stroke onset. Pre-stroke rate of memory decline among future stroke survivors was similar to age-related memory decline in adults who remained stroke-free, but those who died after stroke had faster memory decline.