People born more recently are less likely to have dementia at any given age than earlier generations, research suggests, with the trend more pronounced in women.
According to the World Health Organization, in 2021 there were 57 million people worldwide living with dementia, with women disproportionately affected. However, while the risk of dementia increases with age, experts have long stressed it is not not an inevitability of getting older.
“Younger generations are less likely to develop dementia at the same age as their parents or grandparents, and that’s a hopeful sign,” said Dr Sabrina Lenzen, a co-author of the study from the University of Queensland’s Centre for the Business and Economics of Health.
But she added: “The overall burden of dementia will still grow as populations age, and significant inequalities remain – especially by gender, education and geography.”
Writing in the journal Jama Network Open, researchers in Australia report how they analysed data from 62,437 people aged 70 and over, collected from three long-running surveys covering the US, England and parts of Europe.
The team used an algorithm that took into account participants’ responses to a host of different metrics, from the difficulties they had with everyday activities to their scores on cognitive tests, to determine whether they were likely to have dementia.
They then split the participants into eight different cohorts, representing different generations. Participants were also split into six age groups.
As expected, the researchers found the prevalence of dementia increased by age among all birth cohorts, and in each of the three regions: UK, US and Europe. However, at a given age, people in more recent generations were less likely to have dementia compared with those in earlier generations.
“For example, in the US, among people aged 81 to 85, 25.1% of those born between 1890–1913 had dementia, compared to 15.5% of those born between 1939–1943,” said Lenzen, adding similar trends were seen in Europe and England, although less pronounced in the latter.
The team said the trend was more pronounced in women, especially in Europe and England, noting that one reason may be increased access to education for women in the mid-20th century.
However, taking into account changes in GDP, a metric that reflects broader economic shifts, did not substantially alter the findings.
Prof Tara Spires-Jones, the director of the Centre for Discovery Brain Sciences at the University of Edinburgh, described the study as well-conducted. “The number of people living with dementia is still increasing due to our ageing population, but this study adds to the good news that more recent generations have a decreased risk compared to past generations,” she said.
While the study did not investigate the reasons for the decline, Spires-Jones noted a number of factors could be at play. “This is likely due to interventions such as compulsory education, smoking bans, and improvements in medical treatments for conditions such as heart disease, diabetes, and hearing loss, which are associated with dementia risk,” she said.
Spires-Jones added the study had limitations, including that it did not rely on official diagnoses of dementia based on clinical testing.
Prof Tom Dening, of the University of Nottingham, said the study contained good news but it should not be assumed that the trend would continue, given some of the biggest health changes to reduce dementia risk may already have been made.
Prof Eric Brunner, of University College London, said it was important to look closely at recent trends and the impact of policies such as austerity, given other studies – including his own work relating to England and Wales – have suggested dementia incidence, in other words the rate of new cases, may no longer be declining.
David Thomas, the head of policy and public affairs at Alzheimer’s Research UK, said evidence suggested nearly half of dementia cases could be prevented or delayed by addressing 14 key risk factors – from smoking to air quality – although he noted not all were within individuals’ control.
“That’s why Alzheimer’s Research UK is calling on the government to put in place a strategy for preventing ill-health, including addressing dementia risk,” he said.
