The brain can age more slowly than the body. Neuroscientists reveal what helps it most

The brain is not a passive victim of time. Although it naturally changes with age, it has mechanisms that can slow ageing down considerably. And according to current neuroscience, this is not decided only by genetics or your date of birth, but above all by your everyday habits.

Your brain can be biologically ten years older than the date on your birth certificate suggests. Or, on the contrary, surprisingly younger. The difference rarely comes about by chance. Physical activity, sleep, metabolic health, social contact, mental stimulation and the body's ability to dampen chronic inflammation all play a big part.

And physical activity is proving to be one of the most powerful tools we have. Not as a miracle cure, but as a regular biological signal telling the brain to keep repairing, renewing and forming new connections.

The brain does not age the same way in everyone

Imagine two people born on the same day.

One forgets names, finds it harder to concentrate, feels mentally drained by the evening, and new information only stays in their head for a short while. The other still reads demanding books, makes plans, learns new things, enjoys lively discussions and can stay focused even in more challenging situations.

In the past, we would have put differences like these down to luck, temperament or "good genes". Modern neurology, however, shows that much of the difference comes from the fact that the brain does not age at the same pace in everyone.

What matters is not only chronological age, that is, the number of years since you were born. The biological age of the brain is important too. It reflects the real condition of the brain tissue, the quality of the connections between neurons, the volume of grey and white matter and the overall health of the nervous system.

Today, scientists can measure the brain's biological age using methods such as BrainAGE. It relies on magnetic resonance imaging (MRI) and machine-learning algorithms that analyse thousands of details of the brain's structure and compare them with databases of healthy brains of different ages.

The result can be surprising. Two people of the same age can differ in the biological age of their brains by as much as a whole decade.

And it is not just an interesting number. A higher biological brain age tends to be linked with a greater risk of cognitive decline, dementia and Alzheimer's disease. What is particularly worrying is that neurodegenerative changes often begin long before the first noticeable symptoms.

The brain can be losing volume, flexibility, connections and metabolic resilience for years before a person first notices that they are searching for words more often, forgetting why they set out to do something, or finding it harder to take in new information.

The brain keeps changing throughout life

Until fairly recently, the prevailing view was that after a certain age the brain simply loses performance, bit by bit. Modern neuroscience has changed that view considerably.

The brain is a dynamic organ. It adapts, repairs itself, reorganises and, under certain conditions, can literally rebuild itself, even in old age.

This ability is called neuroplasticity. The brain continually forms new connections between neurons, strengthening some and weakening or dismantling others. This depends on how a person lives, what they pay attention to, what they learn, how they move and what kind of stimulation they regularly receive.

But that is not all it can do. In certain areas, the brain can even create new nerve cells. This process is called neurogenesis, and it takes place mainly in the hippocampus, a small region tucked away in the temporal lobe.

The hippocampus is key to storing long-term memories, finding our way around and learning. At the same time, it is one of the areas most sensitive to ageing, stress and neurodegenerative changes.

According to statistics, after the age of forty the brain gradually begins to lose some of its flexibility. Some cognitive abilities may decline by roughly a few per cent per decade. But a statistical average is not any one person's destiny.

While some people decline more quickly, others keep their minds sharp well into old age. So-called cognitive reserve plays a major role here.

This is the brain's ability to create alternative neural pathways, respond more flexibly to damage and resist harmful changes for longer. The good news is that cognitive reserve can be built. Not overnight, but over the long term – through the way you live.

What dulls the brain faster

When people talk about brain ageing, most think of genetics or the relentless passage of time. In reality, though, the decline of the nervous system involves a number of biological processes that unfold slowly, quietly and often over many years.

Among the most significant risks are metabolic disorders, especially high blood pressure and type 2 diabetes. Both conditions damage the lining of the blood vessels and reduce blood flow to the brain.

And the brain is an exceptionally demanding organ. Although it weighs only a little over a kilogram, it uses roughly a fifth of the whole body's energy. When the supply of oxygen and nutrients starts to falter, nerve cells run into an energy deficit.

The result can be tiring more quickly, weaker concentration, slower thinking and a higher risk of small areas of damage to the white matter. It is no surprise, then, that studies show people with diabetes tend to have an older biological brain age than their healthy peers.

Chronic inflammation also plays an important role. This is not the sudden inflammation that comes with a fever, but a long-term, quiet, barely noticeable irritation of the body. Experts call this process "inflammaging", meaning inflammatory ageing.

During it, the body keeps producing substances that weaken the regeneration of neurons and disrupt neuroplasticity. This is often linked with oxidative stress – a state in which cells face an onslaught of unstable molecules that damage DNA, cell membranes and the nerve connections themselves.

In such a weakened environment, toxic proteins such as beta-amyloid and tau protein build up more easily. They can form abnormal deposits, disrupt communication between neurons and, over time, contribute to their death.

Under normal circumstances, the brain clears away this kind of waste using the glymphatic system. You can think of it as the nervous system's night-time cleaning service. It works mainly while we sleep.

That is exactly why good-quality sleep matters so much for the brain. If we sleep too little or poorly, the nervous system misses out on one of its most essential forms of biological maintenance.

The brain needs stimulation

The brain is also sensitive to a long-term lack of stimulation. A sedentary lifestyle, social isolation, and worsening hearing or eyesight all mean fewer stimuli for the neural network.

Circuits that are not regularly used gradually weaken – rather like a footpath that nobody walks along slowly becoming overgrown.

But it is not just a matter of mental "rust". A chain reaction can begin inside the brain. The blood–brain barrier, the protective filter that separates the blood from delicate nerve tissue, becomes weaker. The brain's immune cells, known as microglia, can slip into a state of permanent alert.

Instead of carrying out repairs, they then react too aggressively and can damage even healthy synapses. Neurons gradually lose their connections and shrink, and some die. On an MRI scan, this process can show up as a loss of grey matter or as enlarged ventricles (the fluid-filled spaces in the brain).

Even so, this is not a hopeless picture. One of the important findings of recent years is summed up quite clearly by the Lancet's standing Commission on dementia: around 45 per cent of dementia cases are linked to factors that can be changed, particularly lifestyle and how we look after our health.

Exercise as biological medicine for the brain

If the brain could choose between yet another dietary supplement and a regular brisk walk, current evidence suggests it would probably pick the walk.

Not because exercise only improves fitness, but because it sends very specific biological signals to the nervous system.

As soon as your muscles start working, they act like a small pharmaceutical factory. They release substances called myokines into the bloodstream. These act as chemical messengers between the muscles, blood vessels, metabolism and the brain.

One of them is irisin, which boosts the production of a molecule called BDNF (brain-derived neurotrophic factor). Neuroscientists sometimes call it, only half-jokingly, "fertiliser for neurons".

BDNF supports the formation of new synapses, protects existing nerve connections and helps neurons survive even in more difficult conditions. In other words, exercise improves not only your muscles but also the environment in which your brain can work better.

Why brisk walking is good for your memory

Of all forms of exercise, aerobic activity has a particularly well-documented effect. This includes brisk walking, swimming, cycling and running.

As soon as your heart rate rises, blood flow to the brain improves. Nerve tissue receives more oxygen and nutrients, blood vessels stay supple, and the risk of small vascular injuries – among the main accelerators of cognitive ageing – goes down.

The hippocampus attracts particular attention. Regular aerobic exercise can bring about visible changes here. Studies show that in people who do endurance activity, the volume of the hippocampus can grow by roughly one to two per cent.

In the context of brain ageing, that is a significant effect. Biologically, it is roughly equivalent to this area becoming one to two years "younger".

These changes are not only visible on MRI scans. People often show better episodic memory, that is, the ability to recall events, information and how they fit together over time. Spatial orientation, the speed of processing information and the ability to focus attention can also improve.

The good news is that the greatest benefit does not come from extreme sporting feats. The brain responds best to regular, moderate-intensity exercise – a pace at which you get slightly out of breath but can still talk.

In practice, this might mean 30 to 60 minutes of activity three to five times a week. The first changes in blood flow to the brain can appear within a few weeks. Structural remodelling of nerve tissue, however, takes months of regular effort.

After all, the brain does not age in sudden leaps. And in the same way, it does not become younger after a single workout. It needs a repeated signal that it has good reason to stay sharp.

Strength training: weights for the body and order in the mind

Most people associate strength training mainly with muscles, a firmer figure or physical performance. But the brain responds to it too – and in a very interesting way.

While aerobic activity mainly benefits the memory centres, strength training mainly supports executive functions. These are the abilities that let us plan, concentrate, filter out distractions, deal with conflicting demands and make decisions more quickly.

It is precisely these skills that often weaken earlier than memory itself.

During strength training, it is as if the brain receives a message that the body must stay ready to cope with demanding situations. That is why many people describe a feeling of mental clarity, calm and better concentration after a workout. According to neuroscience, this is not just a subjective impression.

Increased production of growth factors such as IGF-1 probably plays a part. These support the formation of new neurons, protect nerve cells from damage and work together with BDNF.

Strength training also improves the body's sensitivity to insulin and helps to stabilise blood sugar levels. That is crucial for the brain. Problems with how the body handles glucose are among the significant factors in neurodegeneration, which is why some experts refer to Alzheimer's disease as "type 3 diabetes".

The brain does not like routine

Variety is just as important as the activity itself. The brain particularly benefits from activities that connect body and mind.

Dancing, martial arts, table tennis, juggling and various coordination games are a small puzzle for the nervous system. The brain has to control movement, find its way in space, react to changes, keep its balance and pay attention, all at the same time.

The body is moving, but the neural network is getting an intensive workout too. As a general rule, the more varied the stimulation, the stronger the brain's response.

But the brain does not live on movement alone. It also needs intellectual sparks – new experiences, unexpected impulses and situations that break the comfortable autopilot of everyday life.

Learning a foreign language, playing a musical instrument, reading, changing your routine or even taking a different route to work forces the neural network to look for new pathways. As a result, new connections form and cognitive reserve grows stronger – a mental "cushion" that helps the brain resist ageing and disease-related changes for longer.

Social contact as mental training

Relationships with other people play an underrated role. The human brain is not an isolated processor. It is a highly social organ that evolved in contact with other people.

Loneliness and long-term isolation deprive the brain of important stimulation. An ordinary conversation, on the other hand, is a surprisingly demanding mental task.

During a conversation the brain processes words, tone of voice, facial expressions, body language, unspoken emotions and social context. At the same time, it has to respond, choose the right words, anticipate the other person's reactions and adjust its own behaviour.

This social multitasking is extremely valuable for the nervous system. If you surround yourself with people who inspire you, show you other ways of looking at things and make you think, you are giving your brain a very effective kind of stimulation.

An active social life has one more advantage: it helps to ease stress. Persistently raised levels of cortisol, the stress hormone, can damage the hippocampus and speed up the brain's biological ageing.

How exercise really makes the brain younger

Exercise does not affect the brain only indirectly. Thanks to exercise, the nervous system can physically change.

In certain areas, especially the hippocampus, new nerve cells can form. They gradually become part of existing networks and contribute to better memory and greater cognitive reserve.

At the same time, a kind of biological clean-up takes place. Exercise dampens chronic inflammation, lowers cortisol levels, supports the antioxidant defences of neurons and helps to protect their DNA.

Its role in clearing away toxic proteins is also important, including beta-amyloid, which is associated with Alzheimer's disease. Exercise also supports the health of the blood–brain barrier – the protective filter between the blood and nerve tissue. This makes it harder for substances that fuel inflammation in the brain to reach the neurons.

So with regular exercise, the brain does not just get more energy. It receives a clear biological instruction:

Repair. Renew. Adapt.

And this may explain why even people who only start exercising later in life can show measurable improvements in brain health after a few months.

How much exercise does the brain need?

The good news is that you do not have to train like an elite athlete to have a younger brain. There is no need to run marathons or spend hours at the gym.

The brain responds very well even to sensible amounts of exercise – as long as it is regular and varied.

A simple framework makes a practical starting point:

• 30–40 minutes of brisk walking, 3 times a week, or another aerobic activity that leaves you slightly out of breath but still able to talk.
• A short strength workout twice a week – at home using your own body weight is fine. Squats, lunges, press-ups against a table, resistance bands or simple core exercises are enough.
• A few minutes of coordination or balance every day. You could stand on one leg while brushing your teeth, try a simple dance routine or a new movement, or spend a few minutes juggling.

The results of a study by a team led by neuroscientist Tannaz Saraei, part of the FIT4BRAIN project, suggest that just eight weeks of combined exercise may be linked with a measurable reduction in the brain's biological age.

What matters most is not extreme intensity. It is regularity.

The brain does not work like a savings account where you pay in a large sum once a month and you are sorted. Substances that support neuroplasticity, including BDNF, rise after exercise, but without repetition their effect gradually fades.

The brain needs the same message again and again: this matters, stay in shape.

It is never too late to start

Perhaps the most encouraging finding of all is this: even people who start late often see a real benefit.

The brain responds to change more readily than we long believed. People who start out less fit can sometimes see very striking results, because after years of inactivity their nervous system receives a strong new impulse.

Of course, that does not mean it is a good idea to put off making a change. The earlier you start, the longer you can protect your brain. But it is equally true that it is never too late.

The brain keeps its ability to change, adapt and form new connections even in very old age. The benefits of regular exercise have been seen in people in their eighties and nineties – not only in memory, but also in speed of thinking, orientation, balance and overall mental flexibility.

This is not about going back to being twenty, nor is it a promise of eternal youth. It is about something more realistic and perhaps more valuable: the chance to influence the course of your own ageing.

The brain is not a finished product that simply wears out after a certain age. It is a living, changing organ that is constantly responding to how we live. And when we regularly give it movement, sleep, stimulation, relationships and a reason to work, it can respond surprisingly strongly.

So the future of your brain is not decided by your date of birth alone. To a large extent, it is shaped by small everyday choices – including an ordinary brisk walk.