The most crucial factor here is preventing obesity. “Obesity means you’re more likely to have high cholesterol, diabetes and high blood pressure,” says Tabet. Over a sustained period, he says, all three things “will start to cause damage to the arteries and cause increased inflammation in the brain”.
“The contents of your blood have been found to go through some of the biggest changes in your 40s and 50s,” with some studies finding that some inflammatory proteins “accelerate the ageing of the brain and predict future cognitive health, sometimes by decades”.
What we eat is essential too, as diets can impact the likes of oxidative stress (the imbalance between free radicals and antioxidants in the body, which can cause organ damage) and inflammation, which has been found to play a key role in the onset and progression of Alzheimer’s (the most common form of dementia).
Two regimes have shown potential cognitive health benefits: the Mediterranean diet, and Mind (a hybrid of the Mediterranean and the dietary approaches to stop hypertension, or Dash). The former prioritises at least three servings of fish a week, legumes, nuts, vegetables and fruits; the latter highlights leafy greens (such as Romaine lettuce and kale) and berries (over other fruits). No specific food, or time at which to eat it, has been conclusively proven to reduce cognitive decline, but blueberries, curcumin (found in turmeric) and leafy greens are thought to have anti-inflammatory properties.
Exercise low and slow
“Just being active is important,” Tabet says. “You don’t have to kill yourself exercising.” But habits that are lifelong and consistent is key. “The more you exercise, the more benefit you get.”
Midlife exercising can lead to better brain health later in life, according to research, while other small studies have linked midlife cardiovascular fitness to reduced incidence of dementia in old age. If you struggle to motivate yourself to work out, it may be worth condensing fitness sessions into as few per week as possible as, provided you’re getting the NHS-recommended 150 minutes of exercise, fitting that into one three-hour window is the same as six days of half-hourly slots, he adds.
“Even if you don’t develop dementia, it might slow down the progression, so I would suggest aerobic exercise for people in their 40s,” advises Tabet. Both jogging or power-walking count.
Get no less than seven hours’ sleep
Seven is the magic number for midlife sleepers, says Barbara Sahakian, a professor of clinical neuropsychology at the University of Cambridge. A study she co-authored, charting data from half a million people, found that seven hours of sleep was optimal for those middle-aged and older adults.
“Using data from the UK Biobank, we found that those who slept for seven hours consistently had better cognition, including processing speed, visual attention and memory. They also had better mental health.”
Sleep was the lifestyle intervention most likely to reduce the chances of midlife depression, with those who got seven to nine hours’ sleep, regularly lowering their risk by 22%.
Cut back on booze (and cigarettes)
There is an “additive effect” to years of too many after-dinner glasses of merlot, Tabet says. He also warns that if you drink or smoke to excess past your 40s, “you’re adding to the burden on the brain” (as well as raising the likelihood of ailments such as high blood pressure and heart and liver disease). Stopping doing so in midlife means “you’re cutting down on the harm by taking action earlier”.
Join a Zoom call (or a bike club)
“We keep our brains active through engaging in conversations,” says Sahakian. “While doing so, we gain knowledge and use the information stored in our memory, as well as using our social skills to keep the discussion interesting. By having these conversations, we activate neural networks in the brain, so we are ‘using them and not losing them’.” The advice of Sahakian is to join a running or cycle club, or take up any hobby that might foster connection.
Train your brain
“Learning and remembering are great for the brain and increase the volume of the hippocampus,” Sahakian says. “The hippocampus is important for everyday memory, such as remembering where you left your mobile phone in the house, and this brain area is damaged early on in Alzheimer’s disease.” Tabet adds that keeping the brain sharp in midlife – such as by doing sudokus or crosswords, or learning a new skill – is always very helpful.
Don’t forget to floss
There is a connection between oral health and the development of dementia through inflammation, says Tabet. Bacteria capable of causing gum disease have been associated with multiple forms of dementia in research, as the inflammatory molecules the bacteria make can travel from the mouth through the bloodstream and into the brain. While many matters of dementia prevention may be more challenging, oral hygiene and flossing, and brushing your teeth twice a day is simple in warding off gum issues that could more seriously impact midlife health.
