Maintain Your Muscle to Protect Your Mind
Losing muscle and gaining body fat as we age may trigger immune system changes that diminish brain function, according to a new study published in Brain, Behavior, and Immunity.
Adults with higher amounts of fat in their midsection had worse “fluid intelligence,” or logical, problem solving abilities, as they got older. Having more muscle was linked to better fluid intelligence.
Want to keep your mind sharp as you age? Make some muscle and watch your waistline. For the first time ever scientists have found that less muscle and more body fat may affect our thinking as we age, and changes in parts of the immune system could be responsible, according to a study by Iowa State researchers.
The study, which was published in Brain, Behavior, and Immunity, looked at six years of data from 4,431 men and women, average age of 64. The researchers examined the participants’ changes in lean mass and abdominal and total body fat, and how those body composition changes were related to changes in their fluid intelligence—or logical, problem solving abilities—over the course of the study period.
They discovered that people in their 40s and 50s who had higher amounts of fat in their mid-section had worse fluid intelligence as they got older. Having more muscle mass, on the other hand, was linked to better fluid intelligence. The body composition-brain power link remained regardless of age and education.
“Chronological age doesn’t seem to be a factor in fluid intelligence decreasing over time,” said study author Auriel Willette, Ph.D., assistant professor of food science and human nutrition, in a press release. “It appears to be biological age, which here is the amount of fat and muscle.”
This seemingly unlikely brain-body composition connection appears to be rooted in how body fat impacts the immune system. Previous research has shown that people with a higher body mass index (BMI) have higher levels of immune system activity in their blood, which triggers the immune system in the brain and interferes with cognition.
Jumping off those findings, the researchers in this study looked at body fat and muscle separately (since BMI only takes total body mass into account). They found a clear connection between body fat and increased immune activity.
Among the women in this study, the entire link between more abdominal fat and worse fluid intelligence was explained by changes in two types of white blood cells: lymphocytes and eosinophils. In men, a completely different type of white blood cell, basophils, explained roughly half of the fat and fluid intelligence link.
Having more muscle was associated with better fluid intelligence, but there wasn’t a strong immune system connection.
“Further studies would be needed to see if people with less muscle mass and more fat mass are more likely to develop Alzheimer’s disease, and what the role of the immune system is,” study researcher Brandon Klinedinst, a Ph.D. student in neuroscience, said in the release.
In the meantime, protecting your mind is just another reason to eat a healthy diet and hit the gym to make some more muscle.
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