The three key ages your brain declines dramatically – and what you can do about it
Cognitive decline is natural: it starts to subtly set in by our 40s, and by your mid-50s it’s perfectly normal to find yourself standing in the middle of a room, scratching your head, saying, “Now why the hell did I come in here?”
While the odd midlife memory lapse is a normal part of the ageing process, a new study has found that there are three distinct peaks, when cognitive decline is more evident in all of us. However, these clear spikes seen at 57, 70 and 78 are significantly more pronounced in some people, and the reason for that is simple: lifestyle.
The Chinese study, published in the journal Nature Aging, measured levels in the brain of 13 proteins that are associated with accelerated brain ageing and neurodegenerative diseases. What’s interesting is that the peaks are related to shifts in our lives, from the midlife drop in our hormones to the impact of retirement. The downstream effect they have on our brain is evident years afterwards. But that’s not to say their impact is out of our hands.
Prof Barbara J Sahakian, of the University of Cambridge’s Department of Psychiatry, is the co-author of Brain Boost, a book about the multiple physical and mental actions that support lifelong healthy cognitive function.
She explains the study in its simplest terms: “These key ages in the study are when we begin to see substantial brain changes. At 57, it’s about how well we have managed the physical changes that come with middle age and menopause; at 70, it’s about how well we have kept our brains stimulated in the run up to and post-retirement, and at 78, it’s related to levels of those ‘cognitive reserves’ we have built up by challenging ourselves to do hard things.
“Just like we manage cholesterol long before it causes a heart attack, so too, by adopting lifestyle changes at least 10 years before these peaks described in the study, we can change our future. That’s the key message.”
In short, for brain health we need to both act now, and plan ahead.
Why your brain ages rapidly at 57
When middle-aged spread starts to impact the brain
By 57 your brain is shrinking. It’s a process that starts as early as 30, but it’s now that the reduction in brain volume is clear because of diminishing white matter; the network of nerve fibres which allows the different brain regions to communicate effectively. In short, your broadband is slowing down.
This natural decline is exacerbated by middle-aged spread. Dr Sabine Donnai, a longevity doctor with a special interest in brain health, says weight gain influences our brain functioning in multiple ways. “It is linked to decreased blood supply, hence a decrease of nutrients and essential fats the brain needs, and a build-up of waste products that are not being transported out. Body fat is also inflammatory. Obesity is linked to oxidative stress, those unstable oxygen atoms that damage cells, including neurones.”
Recent research also suggests high cholesterol can increase the risk of dementia, so that’s worth keeping an eye on at your midlife health check.
What you can do about it
The Nature Aging study was done on healthy people, and what was clear was that the poor lifestyle choices of the people with the worst levels of the proteins had had a huge impact. But it works the other way too. Studies show exercise is incredibly neuroprotective. For example, it increases the size of the hippocampus and improves memory.
Prof Sahakian keeps the advice simple. “It’s time to start and keep exercising, which has many benefits, including bone density and preventing depression. The data shows that any exercise that raises your heart rate a bit is better than being sedentary. So the best exercise regimen is one you can stick to.”
Dr Donnai wants us to go about our daily task with added verve. “I get a lot of activity into my day,” she says. “I walk up the escalator. Don’t use your hands when standing up. Push back your chair and get up without using your hands. Don’t say, ‘Lift that for me,’ Say, ‘I can lift that box, I can bend down’. As you go about your daily tasks, be aware of activity that challenges your muscles. In short, don’t stop moving.”
Dr Donnai recommends testing for signs that your metabolism might be struggling, such as blood sugar and cholesterol levels, and keeping an eye on your waist-to-hip ratio. For women, anything over 0.85 is a red flag, while in men it should be below 0.9. For more in-depth analysis of the current state of your brain, Dr Donnai offers a brain assessment programme at her London clinic, Viavi, advising on ways to reduce your Alzheimer’s risk.
She has a shopping list of precautions and treatments. “If you haven’t ever looked at your hormones, do it. Oestrogen, cortisol, insulin and testosterone are all hormones essential to brain health in myriad ways. I always say, you stop your HRT [hormone replacement therapy] the day you want to age. There are large-scale studies that support HRT as being cognition-protective.
“Our lifestyle choices are 90 per cent of both the risk and the fix for cognitive decline.”
Why your brain ages rapidly at 70
The ‘retirement effect’
At 70 we start to see the most well-known of the 13 proteins associated with cognitive decline, tau, accumulate in the brain. There is the cortical thinning that leads to reduced synapse connections in areas responsible for thinking and learning. And there is shrinkage in the frontal lobes and hippocampus, the areas of the brain responsible for higher cognitive function.
The decade before 70 is when we really start to see neural pathways suffer as a result of lowered stimulation levels. “It’s the retirement effect,” Prof Sahakian says. “Around 60, people get a bit comfortable, they might avoid challenging and difficult things and start coasting on experience.” This is a terrible idea. As Prof Sahakian says: “There’s plenty of scientific evidence to support the saying ‘use it or lose it’.”
What you can do about it
Dr Donnai says: “Focus on activities that grow your brain; do not get into the habit of taking the easy option. Don’t settle for sudoku and crosswords; really challenge your brain. Ballroom dancing, a language, table tennis.”
She says we must not be afraid of early testing for Alzheimer’s and cognitive decline. “We can see the protein changes 10-15 years before people become symptomatic and show any evidence of decline. Lifestyle can’t stop it entirely, but the longer you have to make changes and build cognitive reserves, the better the outcome.”
Cognitive reserve describes our resilience to brain deterioration, and it can significantly delay the onset of neurodegeneration and the impact of diseases such as Alzheimer’s and dementia. “In the face of a brain injury or Alzheimer’s, a stored-up cognitive reserve will make you more resilient to its effect,” says Prof Sahakian.
Building cognitive reserves starts in childhood. But a 2022 study published in Neurology found that even people who develop high “cognitive reserve” by the time they reach 69 may reduce their likelihood of memory and thinking decline, even if they have low childhood cognitive abilities. “Ten or 15 years before, we should be embracing new things. It isn’t necessarily about learning Mandarin,” says Prof Sahakian.
Prof Sahakian sees this period as crucial for addressing serious risk factors for dementia and Alzheimer’s: loneliness and social isolation, which studies say can increase the risk of dementia as much as 30 per cent and 60 per cent respectively. “One study showed that five of the 13 proteins linked to brain ageing increased in response to loneliness.”
Humans need socialising and stimulation. If that happens in the pub, she says, so be it.
“Excessive drinking of alcohol is undeniably a problem, but most people enjoy a drink or two if it helps them relax and be sociable. A lot of face-to-face social contact is extremely good for older people.”
In short, sociable chats over a little drink are just what the doctor ordered.
Why your brain ages rapidly at 78
Drawing down on your cognitive reserves
Brain volume further reduces, as does blood flow to the brain. There is an accumulation of proteins linked to inflammation, and cognitive reserves are starting to run out.
What you can do about it
While you might prefer the kids to set up your new telly, the better decision is to work it out for yourself. “IQ is genetic, but education and learning new things is completely within your control,” says Prof Sahakian. “The protective effects of cognitive reserve are well recognised.” Multiple studies show those of us who have developed a deeper well of neuronal connections to fall back on fare better, even when our brain is damaged by age-related decline.
Theresa May famously talked about “girl jobs” and “boy jobs”, but there are great benefits to being able to do all the jobs, according to Prof Sahakian. If your household tends towards siloed roles in a marriage, a little role reversal is just what the doctor ordered.
Dr Donnai says we should be constantly “on top of things that cause inflammation. That means eat well, exercise, relax and avoid sugars and too much stress. Stress is meant to be a reaction to an acute situation – all energy gets shifted towards dealing with the emergency. Chronic stress diminishes the available energy for essential repair and growth functions.”
Avoid too many of those things in our environment that are foreign to our DNA. “The unnatural substances that the body sees as a threat. There are plenty of studies that show insidious effects of chronic, low-level toxin build-up. Our detoxification pathways are incredibly efficient, but they are just overwhelmed by the number of different chemicals in so many of our everyday products,” says Dr Donnai.
We all know about the toxins in cigarettes and alcohol, but there are also risks in everything from food packaging and deodorant to mattresses and takeaway coffee. Use a plastic-free cup and if you get a takeaway drink, don’t suck the hot liquid through plastic. It’s fine on the odd occasion, but day after day, the percentage of microplastics leaking into your drink will accumulate.
Dr Donnai is reassuringly confident in the medicinal power of our lifestyle. “Everything about our brain is geared to fight for its survival. If we support our body with good food, stay physically active and ensure we get adequate sleep, we need not accept the biological decline we associate with ageing.”
Brain Boost: Healthy Habits for a Happier Life by Prof Barbara Sahakian and Dr Christelle Langley is available now
