A new study has found that higher levels of cortisol (a hormone linked to stress) in middle-aged people is associated with smaller brain volumes. These individuals also tend to do much worse on memory and cognitive tests.
The team collected cognitive data from 2,231 participants, with 2,018 undergoing magnetic resonance imaging to measure brain volume. The participants, who were in their 40s and 50s, had their cortisol levels measured in the morning before eating. The team also took into account factors like age, sex, body mass index, and if the participants smoked. Overall, people with higher levels of cortisol were associated with worse brain structure and cognition.
“Cortisol affects many different functions, so it is important to fully investigate how high levels of the hormone may affect the brain,” lead author Dr Justin B. Echouffo-Tcheugui, from Harvard Medical School, said in a statement. “While other studies have examined cortisol and memory, we believe our large, community-based study is the first to explore, in middle-aged people, fasting blood cortisol levels and brain volume, as well as memory and thinking skills.”
An interesting fact about the study, published in Neurology, is that although there were effects correlated with cortisol levels, the researchers didn’t see any symptoms of dementia and all the people in the study were dementia-free. The association between these physical and functional changes in the brain was particularly evident in women.
“In our quest to understand cognitive aging, one of the factors attracting significant interest and concern is the increasing stress of modern life,” added senior author Professor Sudha Seshadri, M.D., from UT Health San Antonio and founding director of the university’s Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases. “One of the things we know in animals is that stress can lead to cognitive decline. In this study, higher morning cortisol levels in a large sample of people were associated with worse brain structure and cognition.”
The team also checked whether or not these higher levels of cortisol were associated with APOE4, a genetic risk factor that has been linked to cardiovascular disease and Alzheimer’s. They did not find a link between the two.
Of course, this study found an association, not a cause. However, the team note it's important that physicians keep an eye on the level of cortisol in patients and that they counsel them on ways to reduce stress, such as getting enough sleep and doing moderate exercise.