Long-term rate of change in memory functioning before and after stroke onset.

BACKGROUND AND PURPOSE Memory impairment is a predictor and a consequence of stroke, but memory decline is common even in healthy elderly individuals. We compared the long-term trajectory of memory functioning before and after stroke with memory change in stroke-free elderly individuals. METHODS Health and Retirement Study participants aged 50 years and older (n=17 340) with no stroke history at baseline were interviewed biennially up to 10 years for first self-reported or proxy-reported stroke (n=1574). Age-, sex-, and race-adjusted segmented linear regression models were used to compare annual rates of change in a composite memory score before and after stroke among 3 groups: 1189 stroke survivors; 385 stroke decedents; and 15 766 cohort members who remained stroke-free. RESULTS Before stroke onset, individuals who later survived stroke had significantly (P<0.001) faster average annual rates of memory decline (-0.143 points per year) than those who remained stroke-free throughout follow-up (-0.101 points per year). Stroke decedents had even faster prestroke memory decline (-0.212 points per year). At stroke onset, memory declined an average of -0.369 points among stroke survivors, comparable with 3.7 years of age-related decline in stroke-free cohort members. After stroke, memory in stroke survivors continued to decline at -0.142 points per year, similar to their prestroke rates (P=0.93). Approximately 50% of the memory difference between stroke survivors soon after stroke and age-matched stroke-free individuals was attributable to prestroke memory. CONCLUSIONS Although stroke onset induced large decrements in memory, memory differences were apparent years before stroke. Memory declines before stroke, especially among those who did not survive the stroke, were faster than declines among stroke-free adults.