Carol was in her mid-seventies when she arrived at Dr Majid Fotuhi’s office. Having retired just eight years prior, she now spent her days mindlessly watching TV, feeling forgetful and confused.
Carol’s sister had brought her in. She was at a loss for what to do and wanted an Alzheimer’s diagnosis so she could sell Carol’s home to pay for her care. It’s an impossibly hard decision countless families have to make, many with the knowledge that, on average, their loved one will live only a handful of years following diagnosis.
This, however, is not that story. Just 12 weeks after visiting Dr Fotuhi, Carol was taking up new hobbies, attending church again, and even applying for jobs. “She was a totally new person,” Fotuhi recalls.
MRI scans of Carol’s brain confirmed what everyone could see from the outside: her hippocampus – the thumb-sized part of her brain responsible for memory and learning – had grown 8 per cent larger in those 12 weeks, equivalent to de-ageing by almost a decade.
What had Fotuhi done to Carol to elicit such miraculous results in such a short span of time? A new drug, perhaps? Or maybe some kind of experimental surgery?
The truth was far simpler. Fotuhi looked at Carol’s life, looking for aspects that could be contributing or worsening her dementia. “Carol had treatable factors, so I said, ‘let’s work on those,’” he says.
Before they met, she was for the most part bound to a wheelchair, receiving multiple medications for back pain. She also had depression, high blood pressure and diabetes.
“We put her on a programme of walking, eating right, sleeping well,” Fotuhi explains. “Within weeks, she started to talk more and be more engaged. As she walked more, she felt energised. As she felt energised, she did more around the house.”
Carol’s story is emblematic of an emerging theory in the science of dementia, one which says we’re not simply destined to either escape it or succumb to it. While the rest of the world has been waiting for a wonder drug to arrive, Fotuhi and colleagues like him have been spreading a different message: anyone – even you – can improve their cognitive function, no matter their starting point. And all it takes is 12 weeks.
We need to rethink dementia
Say the word dementia – an umbrella term describing a group of symptoms associated with memory loss and cognitive decline – and most think of Alzheimer’s, its commonest form.
Alzheimer’s disease is characterised by the formation of harmful protein structures in the brain known as amyloid plaques and tau tangles. Scientists believe that these proteins play a pivotal role in the pathology of the disease, although to this day no one knows exactly how.
But what Carol and scores of patients like her show is that Alzheimer's and other dementias are not the beasts we once thought.
“We have gotten it absolutely wrong,” Fotuhi says. “The misconception is that Alzheimer’s is a single disease that suddenly hits you out of nowhere, and that you’re either lucky and you don’t get hit by Alzheimer’s disease, or you’re unlucky and you’re going to get demented and die in a miserable way.
“The truth, which is well established in the scientific community, is that with ageing, your brain shrinks for many different reasons, most of which are treatable.”
Fotuhi calls these factors a “soup of problems”. Yes, misbehaving proteins play a role in dementia, but so too does poor blood supply, inflammation, poor sleep, strokes and high blood pressure, to name but a few.
Taken as a whole, the ingredients of that soup are mostly dictated by lifestyle. So even if we lack effective therapies for clearing the toxic proteins, there are plenty of interventions that can prevent, slow or even reverse cognitive decline.
The science backs this up – strongly. According to a 2024 Lancet Commission study, addressing 14 lifestyle factors – things like smoking, hearing loss, obesity and depression – could prevent a whopping 45 per cent of dementia cases.
And Fotuhi thinks that figure could be a lowball. “They have not included other factors that can clearly shrink the brain and contribute to dementia because they are difficult to study,” he says. If those were included, Fotuhi states, “I honestly believe that 90 per cent of dementia could be prevented.”
This belief is what propelled Fotuhi to develop his Brain Fitness Program – a 12-week treatment plan with impressive results. According to a study published in the Journal of Prevention of Alzheimer’s Disease, 84 per cent of patients saw improvements in their cognitive function following the treatment. Much like Carol, several patients in the study had their brains scanned in an MRI, revealing that their hippocampus had physically grown too.
Fotuhi, who is naturally proud of the results, boasts: “Not only did they slow the rate of decline, they actually improved their memory, attention and executive function. In my world, much of dementia can be prevented, and even people who have started the early stages of Alzheimer’s disease can slow down the rate of decline.”
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The Brain Fitness Program
Fotuhi has treated thousands of patients over his career, which now spans almost four decades. So popular has the programme become, that his clinic has had to open seven days a week, 8am to 8pm.
But for those unable to make it to his Washington DC clinic, he’s published the Brain Fitness Program in a new book, The Invincible Brain.
The book – which Fotuhi calls the culmination of his life’s work – sets out five broad pillars of brain fitness to work on. These are: exercise, sleep, nutrition, mindset and brain training.
After an evaluation, which involves answering some questions and carrying out some basic tests, each person sets goals to focus on their weak points. “Once we have a thorough baseline assessment, you identify three or four things to work on,” Fotuhi says. “Not everybody needs to work on all five pillars. Most people need to work on two or three.”
So, why these five pillars? And how do you improve each one?
Pillar 1: Exercise
As Fotuhi writes in The Invincible Brain, “If you could do only one thing, change only one lifestyle element, or adopt only one habit, your best bet for growing your brain and becoming invincible against cognitive decline would be to have a regular habit of daily (or mostly daily) exercise.”
When you exercise, blood flow to the brain increases, delivering oxygen and nutrients that neurons need to function. It also increases the number of mitochondria in your brain cells. Remember those so-called ‘powerhouses of the cell’? The more of them you have, the more energy your brain cells have to perform their functions.
At the same time, exercise boosts levels of brain-derived neurotrophic factor (BDNF), a protein that supports the growth, survival and repair of brain cells. “BDNF is sometimes called ‘Miracle Gro’ for the brain,” Fotuhi says.
And just in case that wasn’t enough, regular physical activity appears to stimulate the birth of new neurons in the hippocampus – one of the few regions of the adult brain where this can happen.
The bar is also lower than you might expect. Fotuhi estimates that 5,000 steps a day or more – roughly an hour of walking – can cut dementia risk by 30 to 50 per cent. “It doesn’t have to be running marathons,” he says. “It takes surprisingly little work to generate new neurons.”
The crucial thing is to improve from where you are. That means if you’re very sedentary now, walking may be enough. But if you’re already active in day-to-day life but haven’t put on a pair of trainers in a while, why not take up a new sport?
The Brain Fitness Program is all about tracking progress, and while there are many different ways to do this for exercise, Fotuhi recommends measuring something called your VO2 max as an easy marker. VO2 max is the maximum rate at which the heart, lungs, and muscles can effectively use oxygen during exercise. There are several ways to calculate it, but most fitness trackers and smartwatches will do it automatically these days, which might save you some mental arithmetic.
Pillar 2: Sleep
If exercise is how you build the brain, sleep is how you maintain it.
During deep sleep, the brain activates a waste-clearance system known as the glymphatic system, which flushes out metabolic byproducts that build up during the day – including amyloid proteins linked to Alzheimer’s disease. Chronic sleep deprivation, or conditions like untreated sleep apnoea, disrupt this process.
“If you have poor sleep, perhaps only four or five hours a night, you don’t give your brain the chance to go through the normal rinsing process at night,” Fotuhi explains. “That means metabolic byproducts, which are usually toxic, accumulate in the brain and choke the neurons.”
The impacts of this can be severe. A 2014 study, for example, found that poor sleep in adults – particularly those over 60 – was associated with smaller brain volumes.
Depending on just how bad your sleep is, and whether you classify as someone with insomnia or not, interventions for sleep deprivation might be different. Key actions include regular bedtimes and addressing obvious problems – such as obstructive sleep apnea or excessive late-night screen use.
Fotuhi even recommends some healthy snacks before bed, including yoghurt, which is rich in calcium and tryptophan, and helps the body create melatonin and serotonin.
Pillar 3: Nutrition
The brain is a metabolically demanding organ, consuming around 20 per cent of the body’s energy despite making up just 2 per cent of its weight. What you eat matters.
Fotuhi advocates a Mediterranean-style diet rich in vegetables, fruit, whole grains, fish, olive oil and nuts, which has repeatedly been associated with better cognitive outcomes and larger brain volumes.
Highly processed foods, by contrast, appear to do the opposite. Studies show that diets high in trans fats and ultra-processed foods are linked to increased inflammation and smaller brains.
If cutting everything out at once seems daunting, Fotuhi suggests starting by eliminating added refined sugars like cane sugar and high-fructose corn syrup.
Despite the headlines, supplements are less important than food itself. Fotuhi is cautious here, recommending omega-3 fatty acids (DHA and EPA) as the one supplement with reasonably strong evidence behind it. “But my recommendation is don’t eat junk food,” he says. “That’s a lot more important than taking supplements or not taking supplements. You can’t eat junk food and then take omega-3 fatty acids thinking that you’re now safe.”
Pillar 4: Mindset
Mindset may sound like the vaguest pillar, but its effects are anything but abstract.
Really, this is about stress management. Chronic stress raises levels of cortisol, a hormone that is toxic to the hippocampus in high or prolonged doses.
Over time, this can impair memory and shrink brain tissue. Stress reduction, meditation and reframing negative thought patterns have all been linked to measurable changes in brain structure and function.
Fotuhi also places heavy emphasis on purpose – having a reason to get up in the morning. Retirement, bereavement and social isolation can quietly strip that away, reducing motivation to move, eat well or engage with others. “When you have a clear purpose, the prefrontal cortex, which is the engine to move the rest of the brain, gets engaged,” he says. “Purpose gives you motivation to do things.”
In practical terms, this might mean volunteering, learning a new skill, reconnecting socially or simply setting a goal that feels meaningful. The specifics matter less than the sense of direction.
To measure improvements in your stress levels, Fotuhi recommends tracking heart rate variability (HRV) – the tiny differences between heartbeats. Natural variation is healthy, because it means your heart is adaptable and generally indicates you're better at handling stress. Modern technology again comes to the rescue here, since many smart watches and fitness trackers have this feature built in.
Tracking HRV may allow you to better determine what works for you to reduce stress. It might be meditation, breathing exercises or simply taking a short walk in nature.
Pillar 5: Brain training
Brain training is often the most controversial pillar and the most misunderstood.
Fotuhi is clear that crossword puzzles alone won’t protect you from dementia, especially if the rest of your lifestyle is working against you. But targeted mental challenge does matter. The brain follows a simple rule: what you use, grows.
Learning new skills – from languages to music to navigation – thickens the cortex in the regions being challenged. Even short periods of intensive learning can produce measurable changes.
The key is relevance and effort. “Train the functions you want to be better at,” Fotuhi says. “If you want better memory, do memory games. Let’s say you want to be faster in figuring out numbers – do exercises that will improve that cognitive function.”
Enjoyment matters too, since people are far more likely to stick with activities that feel rewarding rather than dutiful.
However, of the five pillars, Fotuhi concedes that brain training is perhaps the least important. If you have a poor diet, never exercise, can’t sleep and are constantly stressed, half an hour on a brain training app is unlikely to make much of a dent.
It’s not groundbreaking, but it works
Viewed individually, none of these pillars are revolutionary. Exercise is good for you. Sleep matters. Junk food is bad. We’ve known this for decades. So why haven’t these ideas transformed brain ageing already?
Prof Andrew Budson is a neurologist at Boston University who has written his own book about how lifestyle interventions can mitigate dementia risk: Seven Steps to Managing Your Ageing Memory, published in 2017.
“It’s all very standard stuff,” he says. “Is it particularly novel? Not really.” Indeed, similar lifestyle-based approaches already underpin large trials such as the Finnish FINGER study and its US counterpart, POINTER.
And yet Fotuhi’s results are impressive. Perhaps where it differs, then, is its structure – and psychology.
Budson points out that most of our behaviour is driven not by conscious decisions, but by unconscious habits. Knowing what to do is not the same as doing it.
To change your diet or start exercising, it’s not enough to decide,” he says. “You have to train your unconscious brain through routines and repetition.”
A defined 12-week programme lowers the barrier to entry. It feels manageable. It provides feedback. And crucially, it helps people practise new habits long enough for them to stick. “It encourages people to give it a go,” Budson says. “Of course, it’s only going to continue to be beneficial if they continue to do it.”
In other words, the power of the Brain Fitness Program may lie less in what it asks people to do, and more in how it helps them do it. In a world still searching for a miracle dementia drug, the knowledge that your brain is plastic, coupled with the right tools to mould it, may be the real breakthrough.
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