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A new study published in the Journal of the American Heart Association looked at cardiovascular health, Race, and the decline in cognitive function in midlife women.

“Based on our literature review, we hypothesized that cognitive function would decline in midlife,” study author Imke Janssen told us. “But that this decline would be observed in both Black and White women, would be slower for study participants with good heart health, and that the effect would be stronger in White compared to Black women.”

There were several pieces of evidence the researchers found in the literature. Single factors such as chronic health conditions (e.g., hypertension, obesity, diabetes) and lifestyle factors (e.g., smoking, low physical activity, bad diet) have been related to cognitive decline but do not fully explain race differences in either level or decline in cognitive function.

When the combined score of heart health named ‘Life’s Essential 8’ was introduced two years ago, the authors published a companion paper showing that this combination of heart health factors helps identify large group and individual differences in heart health. Therefore, the researchers hypothesized that the combination of heart health factors might have a stronger impact on cognitive decline than any single factor.

“With the aging of the population, the prevalence of dementia is increasing, affecting not just individuals, but also caregivers and health care institutions,” Janssen told us. “Dementia is often preceded by cognitive decline over decades. It is therefore of great interest to determine whether there are modifiable risk factors that could be identified in slowing or delaying cognitive decline.”

The research team used data from a well-characterized group of 765 well-educated women
(363 Black, 402 White) free of clinical cardiovascular disease. Cognitive tests started in midlife in two domains and were repeated every one to two years over up to 20 years. These domains were processing speed and working memory which are the first to decline with age. Processing speed is the pace at which the brain captures accurate visual and verbal information. It is necessary for daily activities such as driving.

In this study, processing speed was assessed as quickly and accurately matching numbers with
pictures. Working memory is the ability to remember and use small pieces of information for daily tasks, including remembering names or directions. The researchers used a series of statistical models to test their hypotheses.

“We found that overall, there was a slight decline in processing,” Janssen told us. “The decline varied by age and race. Women who started testing at an older age declined faster than younger women. However, overall, White women showed no significant decline. On average, Black women showed more cognitive decline than White women. Within the Black group of women, however, cognitive decline varied by heart health.”

Black women with good heart health did not show a decline. The worse the heart health, the more cognitive decline. There was no decline in working memory in contrast to the hypothesis of the research team.

“We were surprised that we did not find results like those of previous studies, which had shown cognitive decline in Black and White men and women and found heart health to be more important for White than Black adults,” Janssen told us. “We believe these differences are due to the younger age of our participants, who began cognitive testing in their mid-40s. Prior studies started with adults about 10 to 20 years older.”

The data came from an observational study and suggest that improving heart health could lead to slower or delayed cognitive decline. This needs to be tested in a clinical trial. Randomized clinical trials are the gold standard in medical research.

“We found heart health to be particularly important for maintaining cognitive function for Black women,” Janssen told us. “Other studies have shown that this is also true for women of other race/ethnic backgrounds as well as for men, although it is possible that the benefit may become apparent later. With the combined evidence from studies conducted in different populations, heart health seems to benefit everyone’s cognition. In addition to controlling blood pressure, weight, blood sugar, and cholesterol, heart health includes lifestyle factors: not smoking, eating healthy food, being physically active, and getting enough sleep. In conclusion, looking after your heart will benefit your brain!”