Why exercise might be best weapon against Alzheimer’s
My grandfather, Abbas Jebelli, was not one for self-gratification. He didn’t drink and kept fit, waking every morning at 5am to go hiking in the foothills of the Alborz Mountains in northern Tehran. He didn’t smoke. And he had a good diet, eating plenty of fish, pomegranates, pistachio nuts and the vegetable-infused, rosewater-scented stews typical of Persian cuisine.
He lived a predominantly stressfree life, too. A property developer, he had inherited a fortune from his own father and was therefore free of financial worries; in truth didn’t need to work. All told, my grandfather’s decidedly salubrious life sheds little light on why he was stricken in his seventies by one of the most terrifying, merciless illnesses of modern times: Alzheimer’s disease.
When I set out to study Alzheimer’s, I never expected to cure the malady myself, but I did want to understand what happened to my grandfather, after watching his memory disappear as it did.
Abbas didn’t live long with his illness; like a candle burning itself out, his mind vanished and faded within seven years. It had reached an unknown destination, somewhere one in three people born in 2015 is bound for, as well. That’s what has driven me forward.
But what — if anything — destined someone towards dementia? More and more it was looking like the Cali- fornian neuroscientist Arthur Toga was right when he replied simply “bad luck”, in response to the same question posed by Terry Pratchett in 2008. Sardonically, Toga went on to say that “this is an equal opportunity disease”.
But as I read the studies on lifestyle countermeasures — and there are many — it became clear to me that there is still cause for hope. Though much of the evidence is preliminary and inconclusive, and sometimes merely anecdotal, considerations for stress, diet, exercise, cognitive training and even sleep are gaining scientific ground.
For many, the top seed in the race for lifestyle interventions is exercise. Even moderate exercise can markedly lower blood pressure and improve cardiovascular health. And it is these resulting rewards that are thought to directly affect Alzheimer’s risk.
Having high blood pressure in middle age, for instance, puts one at higher risk of Alzheimer’s. Conversely, if one’s blood pressure is too low, especially over the age of 75, the chance of Alzheimer’s still increases. Why? That’s unclear. Most evidence points towards a link between blood pressure and inflammation, but exactly how this feeds into the whirlwind of plaques, tangles and brain calamity remains an enigma.
What is conclusive, in lab mice at least, is that exercise on a treadmill can reduce the build-up of plaques and tangles. This modest miracle is thought to happen by activating an intriguing cellular phenomenon called autophagy (Greek for “eating of self ”), a specialised kind of cellular housekeeping that clears out damaged or unwanted goods and introduces new ones after recycling the old, all as part of an adaptive and protective process to help neurons better cope with stress and extend their lifespan.
So it’s thought that stimulating autophagy through exercise may halt the progression of brain cell death in Alzheimer’s.
To take the molecular parlance a step further, a protein called BDNF (brain-derived neurotrophic factor) is the leading actor in this subplot. In December 2010, researchers at the University of Pittsburgh, Pennsylvania, recruited 120 people with an average age of 67 and had them perform either moderate aerobic exercise or simple stretches three days a week.
Strikingly, follow-up MRI scans revealed that those who exercised netted a 2 per cent increase in the size of their hippocampus. That isn’t bad considering that 1.5 per cent shrinkage is normal for this age.
And the middleman in this small victory, it appeared, was BDNF: a molecule kn0own to promote the birth of new neurons and synapses throughout the entire nervous system.
BDNF has such potent effects on neurons, moreover, that pharmaceutical companies now view it as a good drug candidate, causing some scientists to whimsically grant it the rather droll nickname ‘brain fertiliser’.
Such a wonder is, sad to say, perhaps decades away. So in the meantime we must resolve not only to exercise but also to learn what kind of exercise, and how often, is required to keep the mind fit.
The most thorough investigation of the subject so far — a systematic review entitled “The effect of exercise interventions on cognitive outcome in Alzheimer’s disease” by researchers at the University of Sussex, England, in 2014 — found several methods demonstrating positive effects on cognition in Alz-
heimer’s patients.
They ranged from 30 minutes of walking (four times a week for 24 weeks), to one hour of cycling (three times a week for 15 weeks), to 30 minutes of vigorous calisthenics (every day for 12 weeks). For those who have reached an age where even walking is a chore, gentle movements, such as those practised in the Chinese martial art Tai chi, were also deemed worthwhile.
Naji Tabet, chief author in the investigation and a lifestyle research front-runner, emphasised this point when I spoke with him on the telephone. “You do not have to run marathons. You do not have to go to the gym three or four times a week. A brisk walk will do!”
Tabet decided to focus on exercise as a way to prevent Alzheimer’s out of desperation more than anything else. “When you see an illness that robs someone of their personality, their individuality, an illness that ravages their life and the life of their loved ones, you have to treat it in whatever way you can.”
Tabet has looked at what fitness fanatics call Ultra Vets, people in their seventies or eighties who exercise religiously. When Tabet compared a group of Ultra Vets who had no memory problems with an agematched group of people who do what you or I would say is a normal amount of exercise, he found no difference in cognitive skills between the groups.
“So if you overdo it,” he said, “there’s diminished returns. Just do low-intensity exercise. Keep the heart going, keep the muscles going, keep the respiratory system going. Even a couple of minutes a day might protect you.”
But still I wondered, how is this
possible? “Nobody knows exactly how it works,” Tabet granted. “My feeling is that exercise helps the immune system fight the build-up of plaques and tangles.
“But exercise also helps the mood. And we know that people who are depressed are more at risk of Alzheimer’s, so it might have an indirect effect by simply making somebody feel better.”
Fantastical though it might sound, Tabet also thinks that mild exercise can go a step further than prevention. He believes it may actually slow the decline of Alzheimer’s in late-stage patients. He insists that activities as simple as throwing a ball around, gently moving the arms and legs, stretching — anything, in other words, that meets his explicit and unadorned message to “keep things going” — will do something.
If my grandfather were alive today, he’d probably tell you to live like a rock star; the austere life he led certainly didn’t protect him. But still, there’s no denying that the evidence for non-pharmacological countermeasures against Alzheimer’s, albeit conflicting, exists.
Of course, as a scientist, I’d be the first to say that evidence alone isn’t enough — it has to be good evidence: large samples, widely replicated, and so forth — but since we know that these lifestyle measures are good for us anyway, the most sensible approach is to play it safe. So follow a Mediterranean diet. Exercise. Avoid stress. Stimulate your mind. Sleep. You’ve got nothing to lose and everything to gain.
In Pursuit of Memory: The Fight Against Alzheimer’s by Joseph Jebelli is published by Hodder & Stoughton (£20).