Does your brain age faster than the rest of your body?

The brain does not age at the same pace as the rest of the body, but whether it ages faster depends strongly on the individual. Research involving more than 50,000 people shows that biological ageing is not a gradual process: there are acceleration peaks around the ages of 41, 60 and 67. For the brain, peaks of accelerated biological change are visible at 57, 70 and 78, with each peak driven by its own underlying processes, such as inflammation or a decline in repair capacity.

Almost one in five people has one organ that is biologically ageing considerably faster than the rest of the body. The brain and blood vessels stand out in particular: accelerated ageing of the brain or blood vessels predicts the development of Alzheimer's disease just as strongly as the best blood test currently available for that condition. People with a biologically 'old' brain have more than three times the risk of developing Alzheimer's over the following 17 years. That effect is comparable to carrying one copy of the APOE4 gene, the best-known genetic risk factor.

The reverse is also true: a biologically young brain offers strong protection. People with both a young brain and a young immune system have more than half the risk of premature death compared with people in whom both organs are biologically old. Of all eleven organs studied, the brain and the immune system are the two strongest protectors. Other organs do not show this pattern to the same degree.

Brain ageing begins early in life and is accompanied by measurable volume loss, a thinning cerebral cortex and the breakdown of nerve pathways. These are in themselves normal processes, but they lie on a sliding scale towards diseases such as Alzheimer's and Parkinson's. Age is the greatest risk factor for neurodegenerative conditions: one in ten people over 65 has Alzheimer's, and the probability continues to rise with the years.

Whether anything can be done about it remains largely unanswered. A compound called urolithin A, which gut bacteria produce from pomegranate and nuts, improves muscle function in older adults in clinical studies and protects the brain in animal research. For the brain, however, there are as yet no clinical results in humans, and several authors of that research have commercial ties to the manufacturer. Concrete recommendations for slowing brain ageing cannot at this point be derived from the available studies.