May 27, 2021
Older men and women living in neighborhoods with higher poverty rates and fewer educational and job opportunities had more signs of brain aging, including greater brain shrinkage and faster declines on tests of memory and thinking skills. The brain changes are tied to an increased risk of Alzheimer’s disease and other forms of dementia, and add to growing evidence that poverty can have detrimental effects on brain health in both young and old.
“Compelling evidence exists that the social, economic, cultural and physical conditions in which humans live may affect health,” said study author Dr. Amy J. H. Kind of the University of Wisconsin School of Medicine and Public Health in Madison. “We wanted to determine if these neighborhood conditions increase the risk for the neurodegeneration and cognitive decline associated with the earliest stages of Alzheimer’s disease and dementia.”
For the study, published in Neurology, researchers tracked 601 Wisconsin residents for 10 years. Their average age was 59, and none had thinking of memory problems at the start of the study. The researchers had their home addresses, including whether they lived in neighborhoods with the greatest levels of poverty, based on income, employment, education, housing quality and other factors.
Study participants got regular MRI brain scans, including measurements of brain volumes in parts of the brain critical for memory. They also took thinking and memory tests every two years, including tests that measured processing speed, mental flexibility and executive function.
At the start of the study, there was no difference in brain volume between people living in the most disadvantaged neighborhoods and those in other neighborhoods. But at the end, researchers found brain shrinkage in areas of the brain associated with dementia in people in the most disadvantaged neighborhoods, while there was no shrinkage in the other group. Researchers also found a higher rate of decline on cognitive tests that measure risk of Alzheimer’s disease.
“Our findings suggest that increased vigilance by health care providers for early signs of dementia may be particularly important in this vulnerable population,” said Dr. Kind. “Some possible causes of these brain changes may include air pollution, lack of access to healthy food and health care and stressful life events.”
The researchers say that more research is needed to better understand how socioeconomic disadvantages may contribute to poor brain health. But earlier studies have shown that growing up in poverty is associated with disparities in educational achievement, health and employment.
Lack of formal education has long been recognized as a risk factor for Alzheimer’s disease, as have health conditions like diabetes and high blood pressure. Lack of continuous and sustained mental stimulation and daily life enrichment , via a job or in the home, has likewise been tied to an increased risk for dementia.
In many disadvantaged communities, the poor quality or absence of parks and other local public spaces and limited access to novel activities can exacerbate these issues. Poor infrastructures and reduced possibilities for mental activities, along with health issues that can increase Alzheimer’s risk and high levels of daily stressors, can certainly impact the brains of those living in less favorable conditions.
Improving economic opportunities, researchers and policymakers hope, could help to lower the risk of dementia for many. “There are currently no treatments to cure Alzheimer’s disease,” Dr. Kind said. “So identifying possible modifiable risk factors is important.”
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Jack F.V. Hunt, PhD; Nicholas M. Vogt, PhD; Erin M. Jonaitis, MS, PhD; et al: “Association of Neighborhood Context, Cognitive Decline, and Cortical Change in an Unimpaired Cohort.” Neurology, April 14, 2021