Effect is similar for older blacks & whites, U-M and VA team finds.
Having a stroke ages a person’s brain function by almost eight years, new research finds – robbing them of memory and thinking speed as measured on cognitive tests.
In both black and white patients, having had a stroke meant that their score on a 27-item test of memory and thinking speed had dropped as much as it would have if they had aged 7.9 years overnight.
For the study, data from more than 4,900 black and white seniors over the age of 65 was analyzed by a team from the University of Michigan U-M Medical School and School of Public Health and the VA Center for Clinical Management Research. The results will be published in the July issue of Stroke.
Researchers married two sources of information for their analysis: detailed surveys and tests of memory and thinking speed over multiple years from participants in a large, national study of older Americans, and Medicare data from the same individuals.
They zeroed in on the 7.5 percent of black study participants, and the 6.7 percent of white participants, who had no recent history of stroke, dementia or other cognitive issues, but who suffered a documented stroke within 12 years of their first survey and cognitive test in 1998.
By measuring participants’ changes in cognitive test scores over time from 1998 to 2012, the researchers could see that both blacks and whites did significantly worse on the test after their stroke than they had before.
Although the size of the effect was the same among blacks and whites, past research has shown that the rates of cognitive problems in older blacks are generally twice that of non-Hispanic whites. So the new results mean that stroke doesn’t account for the mysterious differences in memory and cognition that grow along racial lines as people age.
The researchers say the findings underscore the importance of stroke prevention.
“As we search for the key drivers of the known disparities in cognitive decline between blacks and whites, we focus here on the role of ‘health shocks’ such as stroke,” says lead author and U-M Medical School assistant professor Deborah Levine, M.D., MPH. “Although we found that stroke does not explain the difference, these results show the amount of cognitive aging that stroke brings on, and therefore the importance of stroke prevention to reduce the risk of cognitive decline.”
Other research on disparities in cognitive decline has focused on racial differences in socioeconomic status, education, and vascular risk factors such as diabetes, high blood pressure and smoking that can all contribute to stroke risk. These factors may explain some but not all of the racial differences in cognitive decline.
Levine and her colleagues note that certain factors – such as how many years a person has vascular risk factors, and the quality of his or her education, as well as genetic and biological factors – might play a role in racial differences in long-term cognitive performance.
But one thing is clear: strokes have serious consequences for brain function. On average, they rob the brain of eight years of cognitive health. Therefore, people of all racial and ethnic backgrounds can benefit from taking steps to reduce their risk of a stroke. That includes controlling blood pressure and cholesterol, stopping or avoiding smoking, controlling blood sugar in diabetes, and being active even in older age.
About this neurology research
In addition to Levine, the study’s authors include Mohammed Kabeto, M.S., Kenneth Langa, M.D., Ph.D., and Mary A.M. Rogers, Ph.D., who like Levine are in the Medical School’s Division of General Medicine; and Lynda Lisabeth, Ph.D., and Andrzej Galecki, M.D., Ph.D. of the U-M School of Public Health. Langa holds a joint position at the U-M Institute for Social Research, which runs the Health and Retirement Survey, the large national longitudinal study from which the data were drawn. Levine and Langa are members of the VA CCMR, based at the VA Ann Arbor Healthcare System. Levine and Lisabeth also hold positions in the Medical School Department of Neurology.
Levine, Langa, Lisabeth and Rogers are members of the U-M Institute for Healthcare Policy and Innovation.
Funding: This research was supported by the National Institutes of Health (grants AG024824, TR000433, AG09740).
Source: Kara Gavin – University of Michigan Image Source: Image is credited to the University of Michigan Original Research:Abstract for “Does Stroke Contribute to Racial Differences in Cognitive Decline?” by Deborah A. Levine, Mohammed Kabeto, Kenneth M. Langa, Lynda D. Lisabeth, Mary A.M. Rogers, and Andrzej T. Galecki in Stroke. Published online May 21 2015 doi:10.1161/STROKEAHA.114.008156
Does Stroke Contribute to Racial Differences in Cognitive Decline?
Background and Purpose — It is unknown whether blacks’ elevated risk of dementia is because of racial differences in acute stroke, the impact of stroke on cognitive health, or other factors. We investigated whether racial differences in cognitive decline are explained by differences in the frequency or impact of incident stroke between blacks and whites, controlling for baseline cognition.
Methods — Among 4908 black and white participants aged ≥65 years free of stroke and cognitive impairment in the nationally representative Health and Retirement Study with linked Medicare data (1998–2010), we examined longitudinal changes in global cognition (modified version of the Telephone Interview for Cognitive Status) by race, before and after adjusting for time-dependent incident stroke followed by a race-by-incident stroke interaction term, using linear mixed-effects models that included fixed effects of participant demographics, clinical factors, and cognition, and random effects for intercept and slope for time.
Results — We identified 34 of 453 (7.5%) blacks and 300 of 4455 (6.7%) whites with incident stroke over a mean (SD) of 4.1 (1.9) years of follow-up (P=0.53). Blacks had greater cognitive decline than whites (adjusted difference in modified version of the Telephone Interview for Cognitive Status score, 1.47 points; 95% confidence interval, 1.21 to 1.73 points). With further adjustment for cumulative incidence of stroke, the black–white difference in cognitive decline persisted. Incident stroke was associated with a decrease in global cognition (1.21 points; P<0.001) corresponding to ≈7.9 years of cognitive aging. The effect of incident stroke on cognition did not statistically differ by race (P=0.52).
Conclusions — In this population-based cohort of older adults, incident stroke did not explain black–white differences in cognitive decline or impact cognition differently by race.
“Cyclic Regulation of Sensory Perception by a Female Hormone Alters Behavior” by Sandeepa Dey, Pablo Chamero, James K. Pru, Ming-Shan Chien, Ximena Ibarra-Soria, Kathryn R. Spencer, Darren W. Logan, Hiroaki Matsunami, John J. Peluso, and Lisa Stowers in Cell. Published online June 4 2015 doi:10.1016/j.cell.2015.04.052