They say that youth is wasted on the young, but could it be that old age is, too? While it’s true that some functions, such as the ability to process new information and learn motor skills, can decline with age, research suggests that ageing brings many cognitive benefits.

In his book The Changing Mind, cognitive psychologist and neuroscientist Dr Daniel Levitin suggests that many of the disadvantages of old age can be offset by developing new habits and attitudes, and by changes to our environment and lifestyle. Far from being a period of decline before death, ageing can bring great joy and satisfaction.

Advances in neuroscience show that some areas of brain faculty actually improve with age. For instance, older, more experienced doctors are better at spotting brain tumours from scans than younger doctors. Pattern recognition, communication and interpersonal skills all increase as we get older and new research shows that memory does not necessarily decline with age.

Dr Levitin also believes there’s too much emphasis on prolonging lifespan and that we should instead focus on increasing “healthspan”, the number of years in which a human is healthy enough both in body and mind to enjoy life. He cites individuals as diverse as Buddhist leader the Dalai Lama and businessman Mr Warren Buffett to show that it is possible to have a happy and productive old age.

You’d have thought that when asked pinpoint the happiest period of their life most people would say their hard-partying university years or carefree childhood. But no. In a study involving thousands of older people in 72 countries, the age that came up most often was 82. In order to reach that level of satisfaction at that age, however, Dr Levitin stresses that we have to take care of ourselves. Here are three of his tips for ageing gracefully and happily.

“The emerging picture is clear,” writes Dr Levitin. “When people retire, they turn in on themselves, then cognitive decline and mood disturbances can take hold.” The challenges of the workplace, it turns out, are the very thing that make it good for you. “Navigating complex social mores and the potential pitfalls of dealing with another human being is about the most complex thing that we humans can do. It exercises vast neural networks, keeping them tuned up, in shape and ready to fire.”

Not everyone is in a position to carry on working as before. Airline pilots, for instance, are mandated to stop flying after a certain age due to safety concerns. Mr Letivin believes the key to a happy old age is to stay active and useful. A retired pilot may choose to pass on their knowledge by, say, becoming a lecturer.

Ageing is an irreversible and inescapable process, but the effects of ageing can be delayed or even reversed by factors that we can control. Diet, sleep, mental stimulation and vibrant social networks are all key, but by far the most important is exercise. “The single most important correlate of vibrant mental and physical health is physical activity,” writes Dr Levitin.

There are the obvious benefits for the body, but systematic meta-analysis showed that for adults with mild cognitive impairment, exercise had significant beneficial effects on memory. Even walking on an unpaved trail requires a huge amount of brain power, including hundreds of micro adjustments to how we use our feet to adapt to the new terrain. The area of the brain most stimulated by this activity is the hippocampus, which is critical to memory formation, and this is why neuroscientists have linked exercise to improved memory function. When it comes to your brain and body: use it or lose it. Just look at Sir Mick Jagger, 76, who has managed to offset a lifetime of decadence and hedonism with an exercise regimen that includes yoga, Pilates, ballet, running, cycling and kickboxing.

Psychologists broadly split personality traits into five key categories: extraversion, agreeableness, conscientiousness, emotional stability and openness. Most people will veer strongly towards certain traits, but many will demonstrate a mix, depending on the context or situation they find themselves in. One trait in particular is key to a longer, happier life. “Perhaps the most important traits to foster and develop throughout the lifespan are those in conscientiousness,” writes Dr Levitin. “Conscientious people are more likely to have a doctor and to go see one when they’re sick. They’re more likely to get regular medical check-ups and keep up with their professional, family and financial commitments.” Conscientiousness traits have been correlated and strongly linked to longer, happier, more successful lives. So, are you the kind of person who files their tax returns late, never makes their bed and always misses their doctor’s appointments? Dr Letivin believes it’s never too late to forge good habits. Just look at Sir Mick, who once sang, “If you start me up, I’ll never stop.”

The Changing Mind: A Neuroscientist’s Guide To Ageing Well by Dr Daniel Levitin (Penguin) is published on 27 February