Obesity ages your brain, claims new study

Brains of overweight people may be 10 years 'older' than their lean counterparts at middle-age, a new study has warned.

According to the research led by University of Cambridge in the UK, from middle-age the brains of obese individuals display differences in white matter similar to those in lean individuals 10 years their senior. White matter is the tissue that connects areas of the brain and allows for information to be communicated between regions.

Our brains naturally shrink with age, but scientists are increasingly recognising that obesity - already linked to conditions such as diabetes, cancer and heart disease - may also affect the onset and progression of brain ageing; however, direct studies to support this link are lacking.

The team looked at the impact of obesity on brain structure across the adult lifespan to investigate whether obesity was associated with brain changes characteristic of ageing. The researchers studied data from 473 individuals between the ages of 20 and 87 and divided it into two categories based on weight: lean and overweight.

They found striking differences in the volume of white matter in the brains of overweight individuals compared with those of their leaner counterparts. Overweight individuals had a widespread reduction in white matter compared to lean people.

Researchers then calculated how white matter volume related to age across the two groups. They discovered that an overweight person at, say, 50 years old had a comparable white matter volume to a lean person aged 60 years, implying a difference in brain age of 10 years.

Strikingly, however, the researchers only observed these differences from middle-age onwards, suggesting that our brains may be particularly vulnerable during this period of ageing. "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," said first author Dr Lisa Ronan from the University of Cambridge. "We can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes," said Ronan.

Despite the clear differences in the volume of white matter between lean and overweight individuals, the researchers found no connection between being overweight or obese and an individual's cognitive abilities, as measured using a standard test similar to an IQ test.

The research was published in the journal Neurobiology of Ageing.