Belly fat may reduce mental agility from midlife onward
 

As middle-aged people age, having more body fat and less muscle may affect their fluid intelligence, says a new study that implicates the immune system.

A study of thousands of middle-aged and older people has linked having more body fat and less muscle mass to changes in mental flexibility with age. The research also suggests that changes to the immune system may play a role.

New research shows why having more body fat than muscle mass can affect cognition from midlife onward.
Researchers from Iowa State University (ISU) in Ames analyzed data on 4,431 males and females with an average age of 64.5 years and no cognitive impairments.

They report their findings in a recent Brain, Behavior, and Immunity paper.

The data came from the U.K. Biobank, which is tracking the health and well-being of 0.5 million volunteers around the United Kingdom. The volunteers were between 40 and 69 years of age when they enrolled during 2006–2010.

The researchers examined the relationship that variations in abdominal subcutaneous fat and lean muscle mass had with changes in fluid intelligence over a 6 year period.

Fluid intelligence refers to reasoning, thinking abstractly, and solving problems in novel situations, regardless of how much knowledge the person has acquired.

In contrast, having more muscle mass appeared to protect against this decline. The team also found that the effect of muscle mass was greater than that of having more body fat.

These links remained even after the researchers adjusted the results to remove the effects of potential influencers, such as chronological age, socioeconomic status, and educational level.