Occupation seems to matter more than years of schooling when it comes to the risk of dementia in old age. A study conducted by a team of researchers from University College London, based on data from over 380,000 adults in the UK Biobank, demonstrated that around three-quarters of the protective effect of education against dementia is actually explained by the type of occupation subsequently chosen.
People who work in fields with high intellectual demand, such as doctors, teachers, lawyers, managers or engineers, reach old age with brains better prepared for aging than those who have been active in jobs with repetitive tasks, whether manual or office. The difference is quite large between the two groups, according to another previous study published in Neurology, the journal of the American Academy of Neurology. People in occupations based mainly on repetitive tasks have a 37% higher risk of dementia after age 70 and a 66% higher risk of mild cognitive impairment compared to those in professions that involve complex thinking, the study concluded.
Occupation seems to matter more than years of schooling
The British study, published in BMC Psychiatry, tried to find out why education is considered a protective factor against dementia. The researchers' conclusion was that the degree itself matters less than the career path it provides access to.
“We found that the level of job complexity explains most of the relationship between education and dementia. People with more education tend to get better-paid and more complex jobs. The benefits for physical and cognitive health then add up,” said study lead author Naaheed Mukadam, professor of psychiatry at University College London.
Type of occupation and risk of dementia
A study conducted in Norway and published in 2023 in the specialist journal BMC Psychiatry reached a similar conclusion. The researchers followed nearly 7,005 people for more than 30 years and cataloged the tasks of more than 300 occupations using a US Department of Labor database that precisely measures how repetitive a job's tasks are.
After taking into account age, sex, education, income, hypertension, obesity, diabetes, smoking, sedentary lifestyle and loneliness, the authors found that repetitive and unstimulating work is associated with a 37% higher risk of dementia, while professions that involve complex thinking may delay the onset of the disease.
The occupations in the “protected” group were those of teacher, lawyer, doctor, accountant, technical engineer and public administration employee. According to specialists, teachers have solid protection due to the fact that they interact a lot with students and parents, they have to continuously learn, explain and analyze information. It's not routine work,” explained Trine Holt Edwin, lead author of the Norwegian study.
The group with repetitive tasks included people who worked in construction, housekeepers, security guards, drivers or assembly line workers. “Our results show the value of an occupation that requires complex thinking for maintaining memory and thinking ability in old age. The workplace is very important for maintaining cognitive health,” emphasized Edwin.
The cognitive reserve hypothesis
The mechanism by which more complex work protects the brain has a name: cognitive reserve. The concept was developed in the 1980s by the American neurologist Yaakov Stern of Columbia University, an author in both studies cited above, to explain a paradox observed since the first autopsies of Alzheimer's patients. Two people with the same brain damage, amyloid plaques and clumps of tau protein can have completely different symptoms. One forgets how to return home, the other remains lucid until the last years of her life.
“The cognitive reserve hypothesis shows that if people are engaged in activities that stimulate them cognitively, then their brains have a more efficient network. Even if signs of pathology appear in the brain, they have other pathways through which different brain areas can still communicate with each other,” explained Jinshil Hyun, assistant professor of neurology at Albert Einstein College of Medicine.
Hyun led a study published in 2022 in the Journal of Alzheimer's Disease, which followed more than 10,000 people in six countries on four continents and confirmed that the type of job predicts the risk of dementia, even after the effect of education is removed. High school graduates had a 26% longer dementia-free lifespan than those who only completed secondary school, and those with complex occupations earned an extra 19% compared to those with routine occupations.
Almost half of the cases can be delayed
The 2024 report by the Lancet Commission on Dementia Prevention, Intervention and Care, led by Professor Gill Livingston of University College London, identified 14 modifiable risk factors that together could prevent or delay up to 45% of dementia cases worldwide. The updated list includes two new factors compared to the 2020 report: high LDL cholesterol in middle age and untreated vision conditions with a high risk of blindness in old age. The rest include low education, hypertension, smoking, obesity, depression, sedentary lifestyle, diabetes, excessive alcohol consumption, head injuries, air pollution, social isolation and hearing loss.
Jobs practiced between the ages of 30 and 65 influence several factors at the same time: how much you train your brain, what income you get, what social contacts you build, how much stress you accumulate.
“We spend most of the day at work, at least eight hours a day. That means a third of the time we are engaged in work, sometimes more. It is a large part of what keeps our brain busy, and therefore it will contribute significantly to the development of cognitive reserve,” said Naaheed Mukadam in an interview with the Washington Post.
What can you do if the job is not cognitively demanding enough?
What solutions are there for a person whose job involves repetitive tasks? The researchers' answer is that the cognitive reserve is built at any age, if we practice any of the activities that keep the mind awake.
First and foremost is continuous learning. “Education increases cognitive reserve, like training a muscle,” Mukadam said. People who read daily, who take classes to learn something new, such as a foreign language, have that essential element for the brain: the need to process new information.
Recreational activities that require concentration also have proven benefits. Research has shown that board games, chess, knitting, crocheting and other fine manual activities train attention, planning and hand-eye coordination. Volunteering brings a double win: it provides that personal purpose associated with better-preserved cognition in old age, and it develops the social circle at the same time.
Social interactions are among the most important protective factors. Real conversations, close relationships, and weekly get-togethers with friends stimulate brain areas that otherwise atrophy in isolation. That is precisely why the years following retirement are a sensitive period.
And the conclusion of most researchers is not to rush to retire from the activity. “Retiring later can protect your cognitive health for longer,” added Hyun.
