What can cause a deterioration in brain health?
Dementia is not a single disease, but a broad term that encompasses numerous conditions affecting the brain. According to Dementia UK, there are more than 200 subtypes of dementia, each progressively destroying brain cells or neurons, preventing them from functioning properly in specific regions of the brain, and affecting a person’s memory, speech and ability to reason and think.
Genetics can make a person more vulnerable to incurring this damage. About 40-65 per cent of people diagnosed with Alzheimer’s disease – the most common form of dementia, accounting for 60 per cent of cases – have a gene called APOE-e4. Genes are also thought to play a particularly big role in dementias that strike at an unusually young age, such as frontotemporal dementia – the version affecting Hollywood star Bruce Willis – which typically begins between the ages of 45 and 64.
Traumatic brain injury is also a known risk factor for cognitive decline. This has been highlighted in recent years by the number of sportspeople who have gone on to develop dementia in later life, particularly those involved in contact sports. In March 2023, a study of male footballers in Sweden found that they were one and a half times more likely to develop dementia than the general population, something that has been attributed to repeated heading of the ball. Recently, Sir Alex Ferguson became the latest sporting heavyweight to add his name to a campaign aimed at making dementia in football an industrial disease.
Lifestyle factors can also contribute to dementia risk, most notably excessive alcohol intake. Regularly consuming more than 21 units of alcohol per week can prove toxic to neurons and blood vessels within the brain, resulting in alcohol-related brain damage. About 10 per cent of all early-onset dementia cases are linked to alcohol.
A diet high in ultraprocessed foods can also be a significant cause. According to a 2022 study in the Journal of the American Medical Association, obesity is now the leading modifiable risk factor for dementia in the US. One of the reasons for this is because it can lead to high blood pressure, damaging the fragile blood vessels in the brain.
Finally, loneliness and social isolation is thought to be one of the most damaging factors for brain health. In 2022, a study in the journal Neurology found that 60- to 79-year-olds who were lonely were three times more likely to develop dementia. This is thought to be because lack of social engagement leads the brain to shrink in size at a much greater rate than normal, affecting the ability to plan and remember instructions.
“It’s incredibly important to stay socially connected,” says Barbara Sahakian, a neuroscience professor at the University of Cambridge. “You have to drive the neural networks in the brain to keep them active through conversation and stimulation. That also reduces stress, which can damage the brain.”
Can dementia and Alzheimer’s be prevented?
In 2020, The Lancet estimated that about 40 per cent of all dementia cases are preventable through making appropriate lifestyle choices, such as avoiding excessive alcohol use in midlife, staying active and avoiding obesity or diabetes through following a healthy diet.
“We don’t have a cure for dementia,” says Garfield. “The damage to the brain is physical damage, and we’re not at a point where we can regenerate it yet. But we know that the signs of cognitive impairment first appear decades before you have a dementia diagnosis. So prevention through lifestyle modifications is key.”
Changing habits to reduce your chances of getting dementia
As well as watching alcohol intake and your waistline, and maintaining social connections into later life, Garfield says that one of the simplest things you can do to try to preserve your brain health is to focus on sleep regularity. This involves going to bed at roughly the same time each night. For while a lot of us stay up later on a weekend, before trying to slip back into a normal sleeping routine during the week, even these little disruptions are unsettling for the brain.
“What we like about this is that it’s an easier public-health message when it comes to dementia prevention than losing weight or going to the gym,” says Garfield. “It’s free, and you can do it by using a sleep diary or looking at your sleep on a wearable device.”
Researchers studying groups of individuals who have lived unusually long lives, for example supercentenarians who live past 110, have found that age-related cognitive decline is far from inevitable, and, in fact, you can keep yourself mentally young by retaining a purpose in later life.
For example, people who keep working throughout their 50s and 60s are more resilient to cognitive decline than those who retire early. Continuing to work part-time or volunteering into your seventh, eighth and ninth decades can maintain what neuroscientists call your cognitive reserve. “Purpose is increasingly associated with maintaining brain function,” says Joyce Shaffer, a psychologist and behavioural scientist at the University of Washington, in Seattle. “The more you continue to do in your 50s, 60s and 70s, the more reserve you have for later on in life.”
Learning a new musical instrument, or returning to one you played as a child, is thought to be particularly stimulating for the brain. In June this year, a study of adults in their 60s and 70s who received six months of weekly piano lessons showed that there was an increase in the volume of the cerebellum, the part of the brain that helps with memory storage and decision-making.
“We’ve seen that music training can improve retention of words, verbal fluency in conversations and processing speed, which you need to make quick decisions, for example when you’re driving,” says Jennifer Bugos, associate professor of music education at the University of South Florida.
Any form of regular exercise is also another proven way of staving off cognitive decline. While brain size naturally decreases at a rate of about 5 per cent a decade after the age of 40, with the rate of decline increasing once you pass 70, research has shown that this shrinkage slows in those who do regular aerobic exercise. This includes any physical activity that gets the blood pumping, such as brisk walking, running, swimming and biking.
But it isn’t just about going for a jog. Working to increase your muscle mass in the gym is actually more important as you get older, and not just because it prevents frailty and falls. Research from the University of California, San Francisco, has shown that having higher levels of lean muscle has a protective effect against Alzheimer’s, too. Using data from 450,243 people in a database called the UK Biobank, individuals with a higher muscle mass were found to have a 12 per cent lower risk of dementia.
“It’s thought that the reason the brain volume is maintained is because there’s an increased rate of production of new brain cells within moments of doing aerobic exercise,” says Shaffer. “But strength training, where you’re working your muscles, is also important for your brain, and that can lead to the production of new brain cells even days later. Both forms of exercise are important.”
What is the latest cutting-edge research or treatment for dementia?
Last year, the US Food and Drug Administration approved a new drug for people in the early stages of Alzheimer’s disease. Called lecanemab, it attempts to slow down the deterioration in memory and cognition. It is not yet available in the UK, and it is also not a cure, and any benefits that patients experience will only be temporary.
Research is ongoing into other medications for the disease, using information that has been found in genetic studies of Alzheimer’s and other dementia.
In April 2022, a study was published in the journal Nature Genetics that identified 75 genes associated with Alzheimer’s. Some were linked to how people process lipids in the brain, to a part of the immune system called the complement system, which can start to malfunction and begin mistakenly killing off the synapses that connect cells in the brain.
Professor Julie Williams predicts that this information could lead to new Alzheimer’s drugs in the years to come. “Genetics has changed our view of this disease in the past five to six years, in terms of influencing new directions for targeting Alzheimer’s,” she says.
There is one form of dementia that is currently curable, known as autoimmune dementia. In this case, the memory loss and confusion are a result of inflammation caused by rogue antibodies binding to the brain, rather than an underlying neurodegenerative disease. Over the past 10 years, neurologists have started to become more adept at identifying cases of autoimmune dementia, which typically progresses much faster than other dementias, with symptoms developing within weeks or months.
Once identified, patients can be treated, and in some cases completely cured through immunotherapy or a treatment called plasma exchange, which attempts to wash the blood of the disease-causing antibodies. “I think this is underrecognised by doctors,” says Eoin Flanagan, who researches autoimmune dementia at the Mayo Clinic. “When they see an elderly patient, there’s often a high suspicion for Alzheimer’s, which we don’t have a treatment for. But some patients can have an autoimmune cause, and it’s particularly vital to spot those ones, because they can be cured.”
What is the connection between hearing loss and dementia?
Hearing has long been connected to brain health from midlife onwards for reasons we are still attempting to understand. Various population studies have shown that dementia risk increases in parallel with the degree of hearing impairment, doubling for mild hearing loss, tripling for moderate hearing loss, and being almost five times greater for severe hearing loss.
There are three main theories for why this might be the case. Julia Sarant, an associate audiology professor at the Melbourne School of Health Sciences, says some scientists have speculated that the very same factors damaging the brain could also be affecting the cochlea, the spiral-shaped cavity in the inner ear that enables hearing. It has also been suggested that lack of stimulation to the auditory cortex – the part of the brain that processes sounds – caused by hearing loss causes it to shrink and slowly degenerate over time.
“Some people also think that difficulty understanding speech increases cognitive load, or the amount of work the brain needs to do to perceive speech,” says Prof Sarant. “This means that the brain must divert resources away from other functions, such as working memory, meaning they start to perform more poorly.”
Some research has suggested that treating hearing loss, for example through hearing aids, could help improve cognition, possibly by enabling people to receive more auditory and environmental stimulation, making them less socially isolated. The findings are not conclusive, but Prof Sarant says it is a practical step that can potentially improve your brain health.
“Consider trialling hearing aids as soon as you are told you have hearing loss,” she says. “It is likely this will protect your cognitive function and, when you are younger, your brain will adapt more easily to the auditory information hearing aids provide. You will be able to make the most of the technology and your brain function will be less impacted by your hearing loss, particularly if it is mild.”
