New research published today reveals a surprising link between geography and the risk of developing dementia in the United States. Scientists from the University of California, San Francisco, conducted the study, which was featured in JAMA Neurology. By analyzing the medical records of veterans, the researchers found significant regional differences in dementia diagnoses across the country, particularly in the Southeast, Northwest, and other areas, even after controlling for factors such as income.
The researchers suggest that these findings highlight the underlying regional differences that may contribute to varying levels of dementia risk. Dementia is increasingly recognized as a major public health concern, especially among older adults. Currently, over 6 million Americans are living with dementia, and a government-funded study released in February projected that 42% of Americans aged 55 and older will develop dementia in their lifetime. This complex condition typically arises from a combination of environmental and genetic factors.
According to senior study author and neurologist Kristine Yaffe, there has been limited research on how dementia risk varies by location at the national level. Yaffe and her team utilized a unique dataset consisting of deidentified records from individuals enrolled in the Veterans Health Administration (VHA), which is the largest integrated healthcare system in the U.S. “The VA national data allowed us to investigate this issue, as the VA has a standardized method for data collection across the country,” Yaffe explained in an email to Gizmodo. “No other national healthcare systems offer this kind of comprehensive data.”
The study monitored the health of over 1.2 million randomly selected VA patients aged 65 and older who did not have pre-existing dementia. These individuals were followed for an average of 12 years. After adjusting for age, the findings indicated that dementia rates were lowest in the Mid-Atlantic region, which includes states like Pennsylvania, Maryland, and Virginia. When this region was used as a baseline, researchers identified that dementia rates were:
25% higher in the Southeast (Kentucky, Tennessee, Alabama) 23% higher in both the Northwest (Idaho, Oregon, Washington) and the Rocky Mountains (Colorado, Montana, Dakotas) 18% higher in the South (Texas, New Mexico, Louisiana) 13% higher in the Southwest (California, Nevada, Arizona) 7% higher in the Northeast (New York)“These differences are substantial, especially considering that all participants are veterans receiving care at the VA healthcare system,” Yaffe remarked. “It was quite surprising to observe such significant disparities.”
The research team hypothesized that variables such as average education levels, the degree of rurality in a state, and the prevalence of other health conditions like heart disease might account for the differences in dementia rates. However, even after accounting for these factors, the regional patterns remained largely unchanged. This suggests that other, less quantifiable influences may play a role in determining why individuals in New Jersey tend to have a lower risk of dementia compared to those in Kentucky.
“It’s possible that lifelong disparities in the quality of education and other social determinants of health are driving some of these differences,” Yaffe noted. The findings from this study open the door to further questions and investigations, which the research team plans to pursue. By uncovering more insights, they hope to discover new strategies for dementia prevention.
