People with mentally stimulating jobs have a lower risk of dementia, according to research.
The scientists looked at more than 100,000 participants in the UK, US and Europe, examining the links between work-related factors and chronic disease, disability and mortality.
They measured cognitive stimulation at work and tracked participants for 17 years to see if they developed the disease.
Lead author Professor Mika Kivimaki, from the Institute of Epidemiology and Health at University College London, said: “Our findings support the hypothesis that mental stimulation in adulthood can postpone the onset of dementia.
“Dementia levels at age 80 seen in people who experienced high levels of mental stimulation were seen at 78.3 years in those who had experienced low mental stimulation.
“This suggests that the average delay in the onset of the disease is about a year and a half, but there is probably considerable variation in the effect between people.”
The researchers said that exposure to cognitive stimulation at work could last for decades, so its benefits would last “considerably longer” than stimulating cognitive interventions or hobbies.
Factors such as age, sex, education, lifestyle, and known risk factors for dementia in childhood and adulthood were taken into account.
The researchers said it is possible that mental stimulation is associated with lower levels of some proteins that could inhibit certain processes in the brain.
While it was long suspected that cognitive stimulation could prevent or postpone dementia, previous trials were based on small samples and short-term interventions.
The researchers said their study was observational only, but its main strength was the large sample size.
A complementary analysis measured cognitive stimulation for 87 public sector occupations.
Those with high encouragement included senior government officials, production and operations managers, directors and CEOs; those with low stimulation included cashiers, agricultural, fishing and related workers, transportation workers, and mobile plant operators.
Dr Sara Imarisio, head of research at Alzheimer’s Research UK, said: “Not everyone can choose the type of work they do, but studies like this highlight the importance of finding activities that help keep the brain active, be it through work or hobbies.
“It is currently unclear which activities are most useful for developing cognitive reserve, so whether it’s challenging work, reading, or learning a language, finding something you enjoy is key.”