What people do for their health in their 50s may influence how well their brains work years later. A new study suggests that staying physically active and keeping blood sugar under control in middle age may be connected with slower decline in memory and thinking.
Researchers at UT Health San Antonio studied adults who had been followed through long-running health projects in South Texas. Their results also suggest that the strongest heart-health factors connected with brain aging may differ between Hispanic and non-Hispanic white adults.
The study was published July 23 in Alzheimer’s & Dementia: Behavior & Socioeconomics of Aging. Researchers from the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases and The University of Texas Rio Grande Valley contributed to the work.
Scientists have become increasingly interested in the connection between the heart and the brain. The same blood vessels that carry oxygen and nutrients throughout the body also keep brain tissue alive and functioning.
When blood vessels are damaged by high blood pressure, high blood sugar, smoking, or other problems, the effects may build slowly for years. This may help explain why poor cardiovascular health in middle age has been linked with a greater chance of dementia later in life.
Alzheimer’s disease is the leading cause of dementia. It gradually damages memory and thinking, eventually making everyday activities such as managing money, preparing meals, or recognizing familiar people much harder.
There is currently no guaranteed way to prevent Alzheimer’s. However, researchers estimate that a meaningful share of dementia cases may be connected with factors that can potentially be changed, including physical inactivity and cardiovascular disease.
The new study examined 402 people from San Antonio whose average age was about 58. Slightly more than half were Hispanic, the rest were non-Hispanic white, and women made up almost 59% of the group.
The participants were originally involved in the San Antonio Heart Study, a major project that began decades ago to investigate diabetes and cardiovascular disease. Some later joined the San Antonio Longitudinal Study of Aging, which examined health and disability as people became older.
Using these records allowed researchers to ask an important question. Could heart-health measurements taken during middle age help predict how quickly thinking abilities changed later?
The team assessed cardiovascular health using seven familiar areas promoted by the American Heart Association. These included exercise, smoking, diet, blood pressure, body weight, cholesterol, and fasting blood glucose.
Fasting glucose is the level of sugar in the blood after going without food for about eight to 12 hours. High readings can signal diabetes or problems controlling blood sugar, both of which can damage arteries and small blood vessels.
Thinking ability was measured up to four times with the Mini-Mental State Examination. The short test asks questions and gives simple tasks that help assess memory, attention, orientation, language, and other basic thinking skills.
When the researchers compared changes over time, physical activity stood out among Mexican American participants. Those who reported at least some physical activity had a slower rate of cognitive decline than those who were sedentary.
For non-Hispanic white participants, blood sugar showed the clearer connection. Fasting glucose of 126 milligrams per deciliter or less was associated with a slower decline in cognitive scores.
These findings do not mean that exercise matters only for Hispanic adults or that blood sugar matters only for white adults. Both exercise and healthy glucose control are important for people generally, and the study was looking for statistical patterns within a relatively small sample.
Exercise may help the aging brain through several routes. It improves cardiovascular fitness, helps the body use insulin more effectively, supports healthier blood pressure, and may improve the flow of blood to brain tissue.
Controlling blood sugar could also protect the brain indirectly. Long-term diabetes can injure blood vessels, increase the chance of stroke, and affect small vessels that supply areas involved in memory and thinking.
The study is particularly useful because Mexican Americans have not always been well represented in dementia research. This matters because Hispanic older adults experience a substantial burden of Alzheimer’s disease while also having high rates of diabetes and obesity in some communities.
Another strength is that the Hispanic and non-Hispanic white participants came from the same general area. This gave researchers a better opportunity to compare the groups within a more similar social and geographic environment.
The team also accounted for age, sex, income, and education when analyzing the results. Additional statistical checks were used to examine whether participants who stopped taking part over time might have affected the findings.
There are important limits. With 402 participants, the study is not large enough to establish that the ethnic differences will appear in other communities, and the researchers themselves called for larger studies.
The research also shows association rather than cause and effect. People who exercise may differ from inactive people in many other ways, and healthier blood sugar may reflect a wider pattern of health behaviors and medical care.
Even with those cautions, the results fit a broader body of evidence linking cardiovascular health with brain health. They suggest that waiting until memory problems begin may be too late to think about some of the factors that shape cognitive aging.
The practical message is not that exercise or a particular glucose number guarantees protection from dementia. Instead, the study strengthens the case for treating midlife as an important period for protecting both the heart and the brain through established healthy habits and appropriate medical care.
The researchers are continuing this work through the San Antonio Heart and Mind Study. By adding brain scans and other neurological measurements, they hope to learn why some people maintain their thinking abilities longer and whether the pathways differ across populations.
In reviewing the findings, the most promising point is that the factors identified are potentially changeable and already matter for general health. The biggest uncertainty is whether the apparent ethnic differences represent true biological or social differences or simply reflect the modest sample size, so they should not yet be used to give different medical advice based only on ethnicity.
Source: UT Health San Antonio.
