A December 2017 study by Iowa State University said,
"Chronological age doesn't seem to be a factor in fluid intelligence decreasing over time … It appears to be biological age, which here is the amount of fat and muscle."
"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,"
."If you eat alright and do at least brisk walking some of the time, it might help you with mentally staying quick on your feet,"