Dementia rates decline among newer generations of older adults

A person aged 75 to 80 is less likely to have dementia today compared to someone of the same age several decades ago, a University of Queensland study has found.

UQ researchers analyzed data from more than 62,000 people over the age of 70 who were born from 1890 to 1948 to determine whether there were generational differences in the prevalence of dementia.

Dr. Sabrina Lenzen from UQ's Centre for the Business and Economics of Health said it was likely improvements in cardiovascular health, education, living conditions and access to healthcare had contributed to the findings.

"We often see statistics that show dementia prevalence rates are increasing – our study doesn't refute that.

As more people live longer, the total numbers of people diagnosed with dementia will grow.

What we found was a statistically significant decline in people from more recent birth cohorts having dementia."

Dr. Sabrina Lenzen from UQ's Centre for the Business and Economics of Health

PhD student Xiaoxue Dou worked with Dr. Lenzen to analyse data from 62,437 people, including 21,069 from the US, 32,490 from Europe and 8,878 from England.

Participants were divided into 8 birth cohorts and 6 age groups.

Cohorts were grouped roughly into 5-birth-year blocks, with the earliest including people born between 1890-1913 and the most recent 1944-1948.

The 6 age groups were 71-75, 76-80, 81-85, 86-90, 91-95, and 96 and older.

"This enabled us to examine how dementia prevalence changes with age and across generations while taking into account when the surveys were conducted," Dr Lenzen said.

She said the results consistently showed people born more recently were less likely to have dementia, including in the US where 25.1 per cent of people aged 81-85 who were born between 1890-1913 had dementia, compared to 15.5 per cent of those born between 1939-1943.

"There has been a lot of improvement in education – particularly for women if, for example, we compare to the baby boomer generation," Dr. Lenzen said.

"We've seen improvements in cardiovascular health, better control of blood pressure and cholesterol – all risk factors for dementia.

"We see this strong correlation between age and dementia, but I think it's really important to understand that it's not just age driving those onsets."

Dr. Lenzen said while the results provided some hope, there was a need for continued investment in public health campaigns.

"Some of the risk factors have been improving but we have been seeing a shift in terms of high obesity rates and things like air pollution," she said.

"We know those are also related to dementia, so it's not certain these trends will continue."

The research was published in JAMA Network Open.