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Alzheimer’s Association: Stressful Life Experiences Age the Brain by Four Years

One new study in Wisconsin found that a single major stressful event in early life is equal…

  • August 13, 2017

One new study in Wisconsin found that a single major stressful event in early life is equal to four years of cognitive aging. It also found that African Americans are most at risk – on average, they experience over 60 percent more of such events than non-Hispanic Whites over their lifetimes.

A second study conducted by a health plan in Northern California found that African Americans born in states with the highest levels of infant mortality had 40 percent increased risk of dementia compared to African Americans not from those states, and 80 percent increased risk compared to Whites not from those states.

These were part of a series of studies reported at the 2017 Alzheimer’s Association International Conference in London.

According to the Alzheimer’s Association, the studies show racial inequities in numbers of people with Alzheimer’s disease and other dementias – even after age 90 – and also point to growing evidence that early life stress and neighborhood conditions contribute to dementia risk in late life.

Racial disparities in the risk for new cases of dementia previously observed in the younger elderly continue into the oldest-old (age 90+), which is the fastest-growing segment of the population.

Researchers found oldest-old African Americans and Latinos had the highest incidence rates compared to Asian Americans and Whites – matching the overall patterns of racial/ethnic disparities in dementia seen in younger elderly.

This is the first time different ethnicities in this older population group have been studied for risk of incident dementia.

The researchers found oldest-old Asian Americans have the lowest cumulative incidence (21%), followed by Whites (31%), Latinos (35%) and African Americans (39%) – matching the overall patterns of racial/ethnic disparities in dementia seen in younger elderly.

In models adjusted for age as the time scale, education, sex, mid-life and late-life vascular comorbidities, oldest-old African Americans had a 28 percent higher risk than oldest-old Whites. Compared to Asian Americans, African Americans had a 30% increased risk of dementia.

Lifetime stressful experiences worsen memory and thinking – more strongly in African Americans

Prevalence of Alzheimer’s disease and cognitive impairment is rising, and the greatest burden seems to be falling disproportionately on historically disadvantaged communities. Despite substantial evidence for racial disparities in later life cognitive health, specific causes remain unclear and the cognitive impact of lifelong adversity is underexplored.

A greater number of stressful events was associated with poorer late-life cognitive function for all study participants.

Even within a relatively small, highly educated sample, African Americans experienced over 60 percent more stressful events than non-Hispanic Whites during their lifetimes, and these experiences were linked to poorer memory and thinking skills in older age.

The researchers determined that, in African Americans, each stressful experience was equivalent to approximately four years of cognitive aging.

Early life conditions – such as high infant mortality rates – may contribute to dementia risk in late life

High infant mortality rates are a marker of adverse social and physical conditions, and birth in areas with high infant mortality rates are associated with a variety of poor health outcomes. Yet, is unknown if birth in states with high infant mortality impacts dementia risk.

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