In the U.S., the state where a person is born has long lasting consequences for his or her risk of dementia in later life, according to a new study—the first to examine the connection between birthplace and dementia risk during old age, according to its authors.
Being born in the ‘Stroke Belt,’ through the Southeast U.S., was associated with a 54 percent increased risk of dementia. The study, led by Paola Gilsanz, with the division of research at Kaiser Permanente in Oakland, California, was published online July 31 in JAMA Neurology.
“Geographic patterning of increased risk of disease can represent clustering of risk factors, some of which are modifiable,” wrote Gilsanz et al. They noted that stroke risk can be the result of the combined effects of several risk factors, many of which are associated with dementia.
“We found place of birth to be a robust risk factor for dementia even after accounting for race, educational level, and life-course vascular risk factors,” wrote the authors. Therefore, they said, it’s plausible that spending one’s early years in one of nine states with higher-than-average stroke risk may also increase a person’s risk of dementia.
The Stroke Belt includes nine high stroke mortality states (HSMSs): Alabama, Alaska, Arkansas, Mississippi Oklahoma, Tennessee, Louisiana, South Carolina and West Virginia.
This cohort study involved 7,423 U.S.-born Kaiser Permanente (KP) members living in Northern California. Participants had had one checkup between 1964 and 1973, during which they reported their birthplace, and data was collected on demographics, lifestyle and cardiometabolic health.
The sample was 18.2 percent black, 74.2 percent white, and 5 percent Asian; 15.7 percent were born in the Stroke Belt. Among those, 68.2 percent were black and 31.8 percent were of other ethnicities.
The authors noted that the site of one’s birth can have an enduring impact upon a person’s lifestyle choices and health behaviors, even when the individual moves far away. In other studies, birth in the nine high-risk states has also been associated with hypertension and atrial fibrillation.
The study deepens understanding of racial disparities in dementia. Dementia risk proved to be the highest for participants who were black and were born in the Stroke Belt. Those nine states, which are predominantly Southern, fall in the poorest region of the U.S. In 1960, 35.6 percent of Southerners lived below the poverty line, compared to 22.1 percent for the U.S. overall, and 14.4 percent in the Northeast. Childhood poverty can affect brain health in many ways, according to the study, including impacts on factors such as nutrition, lead exposure, chronic stress and cognitive stimulation.