Cognitive decline is often viewed as an inevitable part of getting older. But Australian physician and broadcaster Dr Norman Swan argues that ageing does not necessarily mean that our brains are simply deteriorating.

In his new book, The Brain Cliff, Swan examines the science behind brain ageing and explores ways people can protect their cognitive abilities and potentially delay the point at which they experience significant cognitive change.

In an interview with The Guardian, Swan explained that changing how people think about ageing itself could influence how they approach their cognitive health.

Rather than describing what happens to the brain as ‘cognitive decline’, he suggests thinking of it as ‘cognitive change’. Comparing the brain in middle age with how it functioned in our 20s can create the impression that ageing inevitably means losing abilities.

While fluid intelligence, which involves processing speed and problem-solving, tends to peak in early adulthood, another form of intelligence, known as crystallised intelligence, can continue developing. This includes knowledge, experience and wisdom accumulated throughout life.

Swan also highlights a process known as ‘scaffolding’, in which the brain develops additional neural networks that help maintain cognitive function as we age. He compares these networks to the scaffolding surrounding a skyscraper, providing an underlying structure that helps the brain continue functioning effectively.

According to Swan, this scaffolding initially develops across different parts of the brain before becoming increasingly concentrated in the frontal lobes, particularly the prefrontal cortex. This area plays an important role in bringing together thoughts and memories, as well as supporting judgement, decision-making and emotional regulation.

The key, he argues, is to encourage this scaffolding while avoiding factors that can interfere with it.

For The Brain Cliff, Swan interviewed seven people he describes as ‘cognitive super-agers’, individuals who have maintained strong cognitive abilities well into old age. Their backgrounds varied widely, ranging from a 95-year-old shoemaker who was unable to read or write to a woman who taught statistics to Rolling Stones frontman Mick Jagger, as well as a 94-year-old woman still working at a McDonald’s restaurant in Japan.

Despite their differences, Swan found several common traits among them. One was the way they handled stress.

Rather than dwelling on stressful experiences, the super-agers tended to move on, find solutions to problems and avoid prolonged rumination. Swan points out that rumination itself occupies the prefrontal cortex, potentially taking up mental resources that could otherwise be used for cognitive tasks.

He also warns that conditions such as depression and excessive alcohol consumption can affect the prefrontal cortex and potentially bring forward what he calls the ‘brain cliff’.

Why your 40s and 50s matter

Swan says people should begin thinking about protecting their brains during midlife, particularly in their 40s and 50s, although he stresses that it is never too late to start.

Regular exercise is one of his key recommendations. Physical activity can improve brain plasticity, the brain’s ability to adapt and form new connections, which in turn may support the development of neural scaffolding.

Diet can also play a role. Swan advocates an anti-inflammatory diet featuring plenty of vegetables, particularly leafy greens, along with berries, fermented foods such as yoghurt and relatively low levels of red meat. He says such foods can influence the gut microbiome and help support processes associated with brain health.

Another potentially important factor is the brain’s default mode network, which becomes active when the mind appears to be at rest. During these periods, different parts of the brain can form connections that do not usually communicate with each other.

One indication that the default mode network is active is when the mind begins to wander. Swan says mind wandering may actually be beneficial for the brain.

He also points to ‘mental time travel’, which involves remembering the past, staying connected to the present and imagining possible futures. According to Swan, people in midlife may be particularly well positioned to benefit from this process, as they have accumulated enough experiences to draw on while still maintaining a strong orientation towards the future.

What can we learn from cognitive super-agers?

One of Swan’s most significant observations from his research is that genetics may not be as important as many people assume when it comes to determining when cognitive decline begins.

The people he interviewed suggested that environment and lifestyle can have a substantial influence on how the brain ages.

Swan found only one participant whose exceptional longevity might plausibly have been explained by family history. The man, a 100-year-old neuropsychiatrist from New Jersey, nevertheless continued to engage in activities known to stimulate the brain.

He had taken up pencil drawing, attended classes and developed friendships outside his family. For Swan, these activities illustrated the importance of continually learning new skills and maintaining social connections.

How Swan has changed his own lifestyle

Researching the subject has also changed Swan’s own habits.

He says he has become more conscious of when he is ruminating and now makes a greater effort to deal with stress through problem-solving rather than dwelling on it.

He has also reduced his alcohol consumption and become more attentive to cardiovascular risk factors such as cholesterol and blood pressure.

His diet now includes more leafy greens, berries and yoghurt, while moderate to vigorous exercise has become a regular part of his routine.

Swan also has no plans to retire. In fact, he argues that remaining engaged in meaningful work can be beneficial for the brain.

Is stress accelerating cognitive change?

Swan believes prolonged stress and rumination can contribute to cognitive change, although he acknowledges that breaking these patterns can be extremely difficult for some people.

For those struggling to manage them independently, he recommends seeking professional help. Certain forms of cognitive behavioural therapy, when delivered by a properly trained clinical psychologist, can help people change unhelpful patterns of thinking.

Should we avoid retirement?

Swan dedicates a chapter of The Brain Cliff to the provocative idea of ‘Don’t Retire’.

His argument is not that everyone should continue working in the same job indefinitely. Rather, he says remaining mentally and socially engaged is important for maintaining brain health.

According to The Guardian, Swan points to evidence suggesting that cognitive decline can accelerate after retirement. However, he acknowledges that people in physically demanding occupations may not be able to continue working indefinitely.

The important question, he argues, is what people do after leaving their jobs.

Volunteering, taking up new hobbies, learning complicated skills or pursuing other intellectually demanding activities can provide many of the same benefits as employment. In that sense, Swan says, such people have not really retired from an active life.

The alternative, he warns, is spending retirement largely on the sofa watching Netflix, which he considers a poor strategy for maintaining cognitive health.