Individuals who are overweight or obese have brains that appear a decade older than leaner individuals, according to a new study in the journal Neurobiology of Aging.
Our brains normally get smaller with age, but researchers are finding obesity, already associated with conditions like diabetes and heart disease, may also impact the onset and advancement of brain aging; however, direct studies supporting this link are lacking.
In a study that viewed information from individuals at one point in time, scientists reviewed the impact of obesity on brain structure throughout the adult lifespan to investigate if obesity was linked with brain variations manifestation of aging. The team studied information from nearly 470 volunteers between the ages of 20 and 87.
Discovering Differences Between BMI Levels
The scientists split the information into two categories derived from weight: lean and overweight. They discovered striking changes in the volume of white matter in the brains of overweight people evaluated with those of their leaner counterparts. Overweight people had a widespread decline in white matter as opposed to slender people.
The team then determined how white matter volume associated with age across the two groups. They found a difference in brain age of 10 years, with overweight individuals having brains that appeared older.
Strikingly, however, the scientists only witnessed these inconsistencies from middle age forward, indicating that our brains may be significantly susceptible during this period of aging.
“As our brains age, they naturally shrink in size, but it isn’t clear why people who are overweight have a greater reduction in the amount of white matter,” study author Lisa Ronan, a psychiatrist at the University of Cambridge, said in a news release. “We can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes.”
Regardless of the clear inconsistencies in the volume of white matter between lean and overweight individuals, the scientists discovered no link between being overweight or obese and a person’s cognitive abilities, as assessed using a conventional test comparable to an IQ test.
“We don’t yet know the implications of these changes in brain structure,” said Sadaf Farooqi, a professor at Cambridge Neuroscience. “Clearly, this must be a starting point for us to explore in more depth the effects of weight, diet, and exercise on the brain and memory.”
Pictured is a comparison between grey matter (brown) and white matter (yellow) between two people of the same age and sex with different BMI levels. (Image credit: Lisa Ronan)