In the same way that some things age the skin, there are known factors that can prematurely age your brain. Here are five things to avoid if you want to keep your brain healthy for longer as you get older.
See also: Eight ways to keep your brain sharp
See also: Five medical issues that can be mistaken for dementia
Carrying too much weight isn't just bad for your heart and joints – it could also prematurely age your brain. Scientists at Cambridge University found that the brains of obese people look "10 years older" than their slim peers.
Your brain naturally lose white matter (the part of the brain that transmits messages and always it to operate as efficiently) from around the age of 40, but this loss is exacerbated with extra weight. The effect is particularly pronounced in middle-age – so that someone in their 50s who is overweight has the brain of a 60-year-old.
Senior study author Paul Fletcher said: "The fact that we only saw these differences from middle-age onwards raises the possibility that we may be particularly vulnerable at this age. It will also be important to find out whether these changes could be reversible with weight loss, which may well be the case."
2. Doing shift work
There's also bad news for night workers. Researchers at the University of Swansea and the University of Toulouse found that working 'antisocial' shifts prematurely ages the brain and makes people less capable of making informed decisions.
Researchers studied three thousand people and found that those who engaged in shift work for a decade or more performed less well at memory and cognitive ability tests. Those who had worked the night shift had the brain-age of people who were six and a half years older.
There is some good news. Researchers believe that people who quit shift work may be able to recover the brain functionality appropriate for their age. The only downside is that it can take five years for the recovery process to complete.
3. Air pollution
Exposure to air pollution doesn't just increase your risk of cardiovascular diseases, respiratory illnesses, and cancers – scientists now say that pollution can prematurely age the brain and may lead degenerative diseases such as Alzheimer's and Parkinson's.
According to a study from University of Southern California, living in places with high levels of air pollution, such as cities and along busy roads, can lead to 'significant decreases' in their brains' white matter, which is important for mental cognition.
The research focused on the effects of exposure to fine particles, which can come from fires, coal-fired power plants, agricultural and industrial emissions, and cars and trucks. These particles, which are about 36 times finer than a grain of sand, can enter the lungs and travel into the bloodstream, where they cause serious damage to the body.
4. High blood pressure
If you're in your 50s or 60s, here's another good reason to get your blood pressure checked regularly. Having even mildly elevated blood pressure at midlife can prematurely age your brain, according to new research.
Scientists involved with the long-running US Framingham Heart Study found that people who had high blood pressure (a systolic number over 140 or diastolic number over 90), had brains that looked more than seven years older than people with blood pressure in a normal range.
Scientists say the early changes seen with higher blood pressure may set the stage for problems with thinking, memory, and dementia in later life – making it especially important to watch your blood pressure in midlife.
5. Chronic stress
Everyone gets stressed now and then, but if you constantly feel under pressure you could be harming your brain, as well as your heart. Researchers from the University of California–San Francisco found that repeated exposure to the "fight or flight" response (when the body is flooded with cortisol) can cause shrinkage of the hippocampus — a part of the brain involved with stress regulation and long-term memory.
The stress response can cause memory and other aspects of cognition to become impaired, which is a risk factor for Alzheimer's disease and can lead to accelerated memory problems in later life.
Author of The Superstress Solution, Roberta Lee, MD, says: "Patients come in complaining of faulty memory and wonder if they're beginning to get Alzheimer's. Their workups and MRI scans look normal. In the interview, I ask them about their lifestyle and almost invariably they have compounded stress."