The UK population is ageing rapidly, with the number of over-65s in the country growing by nearly 50 per cent in the past five decades. This is very much a positive thing – advances in medicine and public health messaging mean that people are living longer than ever.
But are they happier? Depression is sometimes perceived as a young person’s illness, yet it is becoming increasingly common in the older generations. Statistics suggest that it affects 22 per cent of men and 28 per cent of women over the age of 65, and most shockingly, 85 per cent are thought to get no help at all from the NHS.
Barbara Sahakian, a neuroscience professor at the University of Cambridge, believes we need to start thinking more holistically about factors that can impact mood and lead to symptoms of depression. In a new study published in Nature Mental Health, Sahakian and colleagues examined data from almost 290,000 British people, of whom 13,000 had depression, and identified seven lifestyle factors that can increase risk of the disease, ranging from poor sleep to a lack of social connections.
“We discovered that having a healthy lifestyle reduces risk of depression by 57 per cent,” she says. “Changing our behaviour is something we can do for ourselves. As a society we often focus on our physical health, but we should spend more time focusing on our mental health and wellbeing.”
It is not the first study to identify an effective lifestyle manual for mental wellbeing. Three years ago, a similar study from researchers at Western Sydney University linked many of the same lifestyle factors, along with others such as excessive screen time – particularly in the evening – with depressed mood.
So what are the major lifestyle changes that can help keep you happy long into old age?
The World Happiness Report has consistently found that Finland tops the rankings when it comes to contentment. But it’s not all about saunas, ice swimming and sautéed reindeer. A survey of sleep data from 72,000 people in 26 countries from sleep app SleepScore Labs found that the average Finn sleeps for at least seven hours and five minutes, longer than most other nations.
The connection between sleep and mood is well studied. Sahakian’s study suggests that getting somewhere between seven and nine hours sleep per night remains important for reducing risk of depression throughout life. One of the theories is that getting adequate sleep each night is important for the immune system, which in turn boosts our emotions by dampening down underlying inflammation in the body. “During sleep, the brain recharges itself, removes toxic waste byproducts and boosts immunity,” explains Sahakian. “We also perform better cognitively after having sufficient sleep.”
Many older people find it hard to sleep as well as they did when they were younger. This can be due to other health conditions, such as heart disease, diabetes and chronic pain, but also more simply due to age-related changes in the production of various hormones. As you age, the body produces less of a hormone called melatonin, which coordinates our circadian rhythms.
Chris Fox, a sleep researcher and professor at the University of Exeter, says that it can become a vicious cycle. “If you can’t sleep or you’re consistently waking up early, then the body’s hormonal clock shifts and gets used to less sleep, which can lead to neurochemical abnormalities,” he says.
He advises simple steps such as maintaining a routine, avoiding daytime napping, doing more exercise so you feel tired at night, and eliminating stimulants such as alcohol, caffeine and nicotine.
However, the advent of new drugs could soon help older people with chronic sleep problems. Fox is particularly excited about three drugs called suvorexant, lemborexant and daridorexant, which have been approved by regulators in the US and could soon be available in the UK as well.
“They work by blocking the action of natural substances in the brain that cause people to stay awake,” says Fox. “We’re looking at it as an add-on treatment to depression, because sleep is such a problem for those patients, but maybe it could prevent depression too. They’re seen as wonder drugs for the treatment of sleep, because there’s no addiction potential and you can take them for up to a year.”
Only drink in moderation
Sahakian’s research suggests that keeping alcohol consumption to less than 14 units per week could reduce depression risk by 11 per cent.
While it is well known that depressed people are more likely to turn to booze, alcohol can also exacerbate anxiety and depressive thinking for a number of reasons. A 2022 study in the journal PLOS Medicine showed that alcohol impacts cognition, with people who drink four or five glasses of wine per week experiencing poorer performance on tests relating to concentration, reasoning and reaction time, factors which can impact mood.
“If you’re a relatively heavy drinker over time, that’s going to affect the function of a chemical called dopamine in the brain, which causes a dulling of the pleasure response over time,” says Paul Keedwell, a consultant psychiatrist and Fellow of the Royal College of Psychiatrists.
Alcohol can also disrupt the quality of your sleep, because it suppresses the deepest phase of sleep in which you have dreams, leaving you feeling less refreshed, with less energy and more anxious during the day.
“You definitely sleep better without alcohol,” says Keedwell. “It’s one of those things you don’t think about, like being glued to your phone before bedtime, but the cumulative effect can impact on your mood.”
Improve your number of social connections
Studies have repeatedly shown that the size of our social networks – the number of people who we regularly maintain contact with – steadily increases until middle age and then steadily decreases for the rest of our life, often leading to prolonged isolation in old age.
Unsurprisingly, this has a knock-on impact on mood. “If you look at the demographic factors that put you at most risk of suicide, two of the key ones are being divorced and living alone,” says Keedwell. “It often seems to be an inevitable part of growing older, having fewer social contacts. You lose contact with people when they have kids, or when you have your own kids, and then when those kids are grown up and leave home, you’re quite isolated. But it’s important to keep those social networks active.”
However, it’s not just the size of your social network which is important for preventing depression, but the quality of those connections. In a 2019 study of older adults in the journal Psychology and Aging, those with the larger number of close friends were most likely to report greater wellbeing.
“My uncle lived to 95 and he was never depressed, and constantly socially active,” remembers Keedwell. “His 80th and 90th birthdays were both really well attended, and I remember thinking that was quite rare, and a good example of being an energetic older person and having a big social network.”
Earlier this year, University of South Australia researchers published a scientific review in the British Journal of Sports Medicine which showed that physical activity is one and a half times more effective than counselling or antidepressants as a way of managing symptoms of depression.
All types of exercise interventions were found to be effective, from yoga or Pilates, to lifting weights or taking up swimming, with many people experiencing a boost to their mood within 12 weeks.
Sahakian’s study also highlighted the benefits of exercise for reducing risk of developing depression, and there are various reasons why. Movement releases feelgood endorphins that can enhance your sense of wellbeing, while exercise also triggers the production of a neuroprotective molecule called BDNF, which is found to be lacking in the brains of depressed patients.
“I often tell people that BDNF is going to become your favourite four letter word,” says Joyce Shaffer, a psychiatrist and behavioural scientist at the University of Washington, in Seattle. “Particularly when you do aerobic exercise, which is when your heart rate is elevated, your brain cells create more BDNF, which makes them and their neighbouring cells healthier and improves your mood.”
Eat an anti-inflammatory diet
It has only been relatively recently that we have begun to realise the extent to which the vast colonies of microbes in our gut – populations of bacteria, viruses and fungi which are influenced both by our genetics and our diet – can impact our mental health.
One of the reasons for this is something called the vagus nerve, a bundle of nerve fibres that detects signals from microbes throughout the gastrointestinal tract and runs all the way to the brain.
“Roughly 80 per cent of the cells that make up the vagus nerve are signalling in the direction from the gut to the brain, while only 20 per cent are the other way round,” says Katerina Johnson, a psychiatry researcher at the University of Oxford. “It highlights how much the brain is a receiver of information from our gut.”
Eating a diet high in ultra-processed foods can drive inflammation in the gut, which in turn can stimulate inflammatory processes in the brain. However, it appears that eating a diet high in fibre, a type of carbohydrate found in fruit and vegetables, can actually protect against depression. One scientific review published in 2021 suggested that adults who ate a high-fibre diet were 10 per cent less likely to become depressed.
According to Ted Dinan, a professor of psychiatry at University College Cork, one of the reasons a high-fibre diet is thought to be important for mental health is because bacteria in our gut feed on it and use it to manufacture an important amino acid called tryptophan. In turn, the brain uses tryptophan as the building block for the hormone serotonin, which regulates our mood.
“We know that if somebody starts off on a good diet, and then goes on a diet of fast food, their microbiota changes in a short period of time, and helpful microbes in the gut tend to be lost or decreased dramatically,” says Dinan. “One of the consequences of that is that we don’t then deal very well with stress.”
Develop a healthy lifestyle at a young age
While these five lifestyle hacks can help your mood at any age, Sahakian is hoping that this research will lead to more concerted efforts to help the development of healthy lifestyle habits from as young as possible.
“Schools should teach children about the importance of a healthy lifestyle for promoting brain health, mental health and wellbeing,” she says. “It can have enormous benefits for you throughout the course of your life.”
What do you do to lead a happy life? Join the discussion in the comments below