How your neighborhood can play a role in brain size, risk for cognitive decline

Living in a disadvantaged area could lead to brain shrinkage, dementia, and Alzheimer’s disease, a new study suggests. Middle-aged and older people living in areas with lower incomes, poor education and employment prospects, and worse-quality housing experienced cognitive decline, while their counterparts in rich areas were fine, say researchers.

The team behind the findings, from the University of Wisconsin, believes the causes for the neurological decline of underprivileged residents could include air pollution, lack of access to healthy food and healthcare, and stressful life events.

“Worldwide, dementia is a major cause of illness and a devastating diagnosis. There are currently no treatments to cure the disease, so identifying possible modifiable risk factors is important,” said Dr. Amy Kind from the University of Wisconsin School of Medicine and Public Health in Madison, in a statement.

“Compelling evidence exists that the social, economic, cultural, and physical conditions in which humans live may affect health. 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, 610 Wisconsin residents with an average age of 59 underwent a series of MRI brain scans over a period of ten years. With each scan, researchers measured brain volume in areas of the brain linked to the development of Alzheimer’s dementia. Participants also took thinking and memory tests every two years, including tests that measured processing speed, mental flexibility, and self-control.

Researchers used the residential address of each participant and a measure called the “Area Deprivation Index” to determine whether each participant lived in an advantaged or disadvantaged neighborhood. The index, which divides towns into areas of 1,500 residents, takes into account socio-economic factors including income, employment, education, and housing quality to give them an overall score.

When the study began, scientists noted no difference in brain volume between people living in the most disadvantaged neighborhoods and those in other areas. But by the end of the ten years, they found brain shrinkage in areas of the brain associated with dementia in people in the worst-off places, while there was no shrinkage in the other group. Researchers also found a higher rate of decline in tests that measure the risk of Alzheimer’s disease.

“Our findings suggest that increased vigilance by healthcare providers for early signs of dementia may be particularly important in this vulnerable population. Some possible causes of these brain changes may include air pollution, lack of access to healthy food and healthcare, and stressful life events,” says Dr. Kind. “Further research into possible social and biological pathways may help physicians, researchers and policymakers identify effective avenues for prevention and intervention in Alzheimer’s disease and related dementia.”

The study is published in the journal Neurology.

SWNS writer William Janes contributed to this report.

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