Researchers studied 7,423 California residents collecting health data on them from 1964 to 1973, then following up by examining their health records in 1996 to 2015. The average age was 43 at the start of the study, 71 at the end.
They found that people who were born in nine states where rates of stroke are higher than in the rest of the country – the so-called “stroke belt” states of Alabama, Alaska, Arkansas, Louisiana, Mississippi, Oklahoma, Tennessee, South Carolina and West Virginia – had a higher rate of dementia, even after they had moved to California.
The study, in JAMA Neurology, found dementia in 39 percent of those born inside the stroke belt, but 28.8 percent of those born outside. Adverse social and economic conditions early in life, the researchers say, may be contributing to the higher rates.
There were racial disparities as well. Black people are more likely to be born in the stroke belt and, regardless of where they are born, have a higher risk than whites.
“Future research needs to take a closer look at geographic patterns of dementia risk, and understand how they contribute to racial disparities in rates of dementia,” said the senior author, Rachel A. Whitmer, a senior research scientist at Kaiser Permanente in Oakland, Calif. “It’s pretty powerful that we see these differences.”
This article originally appeared in The New York Times
For more information, see the Division of Research’s Spotlight “Early Adversity, Birthplace Contribute to Lifelong Racial Disparities in Dementia Risk.”