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THE studies are cruelly consistent: by the age of 45, your basic cognitive abilities begin to slip. As we get older, the crucial brain regions involved in memory, attention and perception begin to shrink and no longer communicate with one another as efficiently as they once did. You may find that you aren鈥檛 quite as quick as you once were. It takes longer to recall where you left your keys, more effort to help your kids with their maths homework.

Except that isn鈥檛 the final word. There are plenty of science-backed strategies for keeping your brain fitter for longer. And it is never too late to begin.

1. Flex your mental muscle

The brain is often likened to a muscle, and for good reason: give it a good workout and it will stay strong. But what does that really mean?

A few years ago, headlines were full of claims about brain-training apps and computer games that offered a shortcut to improved cognitive fitness. But these have largely been debunked. 鈥淭here鈥檚 no magic activity that will do it,鈥� says , a neuropsychologist at Columbia University in New York.

Instead, the trick seems to be to find activities that boost what鈥檚 known as cognitive reserve. You can think of this as spare mental capacity, a kind of extra padding that allows your brain to sustain more damage before you feel the effects. The concept has been used to explain why two people with Alzheimer鈥檚 disease, and the same amount of damaging protein plaques in their brain, may not be equally affected.

Studies have linked this cognitive reserve to . This helps explain why, with better education, rates of dementia have fallen in developed countries (even if absolute numbers have risen because people live longer). But regardless of your education, there is still time to adopt activities that bring the same benefits. One option is to be socially active (see 鈥淢ix and mingle鈥�). 鈥淎nything that people enjoy and has a social component should be fine,鈥� says Stern.

If you want to pick a winner though, there seems to be something special about music and language. For instance, people who played an instrument as a child, even for a few years, tend to be from decline in the brain areas associated with hearing (see chart). And people who speak more than one language develop dementia later, on average, than monolinguals. A 2018 study found that musical training and speaking a second language both , requiring less energy to accomplish the same cognitive tasks. Music to our ears.

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2. Get moving

It is one of the lesser known benefits of pounding the pavements, but regular physical exercise can do wonders for your mental fitness. The evidence is conclusive, says neuroscientist at the University of Illinois: 鈥淓xercise helps promote a healthy brain and mind.鈥�

Exercise increases the production of a chemical called brain-derived neurotrophic factor. Sometimes referred to as brain fertiliser, it spurs the creation of neurons in the hippocampus, a part of the brain that helps consolidate memories, and new connections between them. It also boosts the number of mitochondria, the energy factories of cells, inside the brain. Together, these changes seem to bolster the brain against and Alzheimer鈥檚 disease. It isn鈥檛 clear exactly how exercise translates into a brain boost, although one idea is that it is down to .

You don鈥檛 have to start running marathons to reap the benefits. Doing moderate exercise such as walking, cycling or swimming between three and five days a week for 45 to 60 minutes , says Kramer.

3. Look after your ears

Your parents probably told you to wash behind your ears, but it is far more important to take care of their insides. People with mild hearing loss are more likely to develop cognitive issues. Neuroscientist at Brandeis University in Massachusetts has found that impaired hearing hinders people鈥檚 ability to remember information they have just heard.

Why so? The hypothesis is that when you struggle to hear, the extra concentration involved comes at the cost of other mental processes. 鈥淚鈥檓 so busy trying to focus and recognise the words that there鈥檚 nothing left to help me remember those words,鈥� says Wingfield.

Mild-to-moderate hearing loss affects between 40 and 50 per cent of people aged over 65, but it is usually easy to correct. Get your ears checked regularly and bear in mind that the most common sort of hearing loss can be rectified with a hearing aid that amplifies the frequencies the ears are insensitive to.

You can also protect your ears by keeping the volume down when watching the TV or listening to music 鈥� even short bursts of loud noise such as at gigs can damage nerves in the ears. So next time you go to a concert, take some earplugs. Your brain will thank you for it.

4. Chill out

A couple of years ago, at New York University published details of a strange study. She had followed the lives of 8000 people in China for 13 years, recording their cognitive function and tooth count. She found a strong correlation between , even after accounting for the natural changes that occur in both with age.

The finding still needs to be backed up, but it could be part of a wider link between inflammation, the body鈥檚 response to injury or attack, and brain health.

Inflammation can be a natural and helpful process. Cut your foot, say, and the area will quickly get hot and red as blood vessels dilate and release fluids and immune cells to fend off foreign microbes. But some aspects of modern life, particularly stress, can trigger a chronic inflammatory response, which spreads throughout the body. This isn鈥檛 helpful and the longer it lasts, the worse its effects.

Inflammation in the brain increases the activity of a neurotransmitter called glutamate. That leads to the shrinkage of individual brain cells and a reduction in their formation. 鈥淚t鈥檚 part of the cascade that can lead to the destruction of brain cells and on to dementia,鈥� says , a neuroscientist at the Rockefeller University in New York.

Tooth loss, then, is just another hint at the deeper problem of inflammation. It typically results from poor oral health, which comes with inflamed gums. It doesn鈥檛 mean that taking better care of your teeth is a guaranteed route to better cognitive function.

Equally important is to properly manage your stress. There is some evidence that meditation and mindfulness practices can help by dialling down inflammation. A 2018 analysis by researchers at the University of Nevada looked at seven studies of how mindfulness meditation helped reduce older people鈥檚 stress levels. One study on 34 adults who had taken mindfulness classes over eight weeks found they had significant . Maybe that鈥檚 something to practise next time you are in the dentist鈥檚 chair.

5. Find your purpose

From zookeepers to doctors, researchers have been asking people for decades what makes their jobs meaningful. The results boil down to six factors. Authenticity, the feeling that you can be your true self at work, was on the list, as was a sense of belonging. If these tally with your working life, it also bodes well for your mind: finding a purpose in life is a sure way to stave off mental decline.

One of the largest studies demonstrating this was published in 2017. Nathan Lewis at Carleton University in Canada and his colleagues phoned 3500 people and asked them about their sense of purpose. Those whose answers suggested they felt that their life had direction and their actions were guided by overarching goals tended to .

鈥淎s brain workouts go, there is something special about learning an instrument鈥�

McEwen says this fits with what we already know. A sense of purpose can provide motivation and end up pushing people into activities that help build, you guessed it, cognitive reserve. It tends to make you more active and more social. 鈥淎nd we know that these improve overall health, including brain health,鈥� says McEwen.

Finding purpose doesn鈥檛 necessarily require you to quit your job and join the Red Cross. As the career surveys showed, meaning comes in many flavours. Maybe your job aligns with your core values. Or maybe your colleagues give you a sense of belonging.

If those elements are lacking, volunteering with local organisations, helping to raise your grandchildren or cultivating a hobby you are passionate about can do the trick.

6. Mix and mingle

Like it or not, humans are social animals. And it turns out that hanging out with other people can help preserve cognitive health in a similar way to activities like learning an instrument 鈥� yes, it is about building that all important cognitive reserve (see 鈥淔lex your mental muscle鈥�).

Some of the evidence comes from studies of married couples. In a 2018 analysis, , a psychiatrist at University College London, and his colleagues demonstrated that . He says the differences are probably due to regular conversation and the effort involved in maintaining a good relationship between spouses. So you don鈥檛 need to tie the knot to reap the benefits. 鈥淭here鈥檚 no one type of social contact that is better than another,鈥� says Sommerlad. 鈥淚鈥檇 recommend social contact that you enjoy.鈥�

7. Get your Zs

You already know from bitter experience that a bad night鈥檚 rest makes you grumpy. But the effects are more insidious. Study after study suggests that not getting enough of the right kind of sleep can have long-term impacts on the brain.

One of the most important findings came in 2013, when neuroscientist , now at the University of Copenhagen in Denmark, that during sleep is when the brain gets rid of the biochemical gunk that accumulates throughout the day. That includes the proteins that can build up into the telltale plaques and tangles seen in neurodegenerative diseases like Alzheimer鈥檚. 鈥淲e now see the function of sleep is to help clean the brain,鈥� says Nedergaard. 鈥淚t is very important to take sleep seriously and develop strategies to sleep well.鈥�

What does that look like? The recommendation is to get 7 to 8 hours every night. We also know that the different phases of sleep have varying functions. For instance, our deep, non-rapid eye movement sleep is known to be involved in laying down new memories. This sleep comes in sections separated by about 2 hours, so if you sleep less than the optimal amount, you are robbing yourself of them.

If you struggle to doze off, there are plenty of things to try aside from the standard advice of drinking and smoking less. For example, warnings about the short-wavelength blue light from phones and tablets disrupting the production of the body鈥檚 sleep-regulating hormone, melatonin, are spot on. So switch off a good few hours before bed. Another neglected factor is having the right temperature in your bedroom. You want to aim for between 18 and 21掳C.

8. Mind what you eat

The Paleo, the keto, the 5:2, the Atkins 鈥� our obsession with fad diets isn鈥檛 going away. Most of them claim to keep us physically healthy and shift a little weight. But what should you eat to keep your mind sharp?

You might have heard of the benefits of the Mediterranean diet, which recommends eating plenty of fruit, vegetables, whole grains and olive oil. It does seem to keep us healthy, cutting the risk of heart disease and early death. But recently a few studies have begun to suggest it can .

Yet the Mediterranean diet isn鈥檛 designed to specifically include foods that we think benefit the brain. So , a nutritionist at Rush University in Chicago, tweaked the Mediterranean diet, trying to optimise it for brain health. The result, which she called the MIND diet, emphasises eating leafy green vegetables and berries, drinking wine, and limiting cheese, sweets and fried food (see diagram).

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Berries are on the list because people who eat them generally have better cognitive abilities. This might be because they contain lots of antioxidants, chemicals that protect cells from damaging free radicals. The same is true of leafy vegetables. Foods that are high in saturated fat or sugar are no-nos because of their association with inflammation in the brain and body.

To assess the diet, Morris studied 923 people living in retirement homes near Chicago. She randomly assigned them to eat either the Mediterranean diet, another plan called the DASH diet, designed to lower blood pressure, or her MIND diet. She found the MIND diet outperformed the others, for those who stuck to it most strictly.

In 2017, a larger study backed this up. Ken Langa at the University of Michigan looked at the 91色情片 and Retirement Study, a huge study of how people in the US have aged, which has run since 1990. He assessed participants鈥� diet records and collated data on those who had eaten the Mediterranean or MIND diets. People who stuck to them had .

As for the drip-drip of headlines touting the cognitive benefits of individual superfoods, Langa counsels restraint. Protecting your brain with your diet means paying attention to your whole diet, there鈥檚 no one food that will do it.