Older adults have reason to be cheerful, as the risk of neurodegenerative diseases is declining. (stock image).Image: Keystone
As populations age, diagnoses of dementia are expected to rise. However, a surprising trend has emerged: the risk of developing dementia has significantly decreased over the past 40 years. Understanding the factors behind this decline is crucial for public health planning and individual well-being.
February 15, 2026, 12:10February 15, 2026, 12:10
Sabine Kuster / ch media
Much has changed in the last 130 years. People now live an average of 36 years longer than those born around 1900. This raises the question of whether our brains are keeping pace with increased longevity.
Initial projections weren’t optimistic. According to forecasts, the number of people with dementia is expected to double in Switzerland and triple worldwide by 2050, as detailed in research published by The Lancet.
A Significant Decline in Prevalence
This projection suggests a massive increase in the need for care. Alzheimer Suisse estimates that 315,400 people will be affected by dementia in Switzerland by 2050. A longer average lifespan naturally increases exposure to cognitive decline.
However, a critical piece of information is often overlooked: the individual risk of developing dementia has fallen dramatically. A 2025 study by researchers at Duke University School of Medicine revealed that the number of dementia cases per age group in the United States decreased by two-thirds between 1984 and 2024.
Their function confirms this trend in several countries, not just the United States. Sweden, the Netherlands, the United Kingdom, and France have all recorded similar developments, despite using different data collection methods.
source: P. J. Eric Stallard et al., JAMA, volume 33 / Graphique: let
Researchers illustrate this decline in a striking graph: the later a cohort was born, the lower the prevalence of dementia. Among those aged 85-89 born in the U.S. Between 1895 and 1899, 30% had dementia. This figure dropped to 13% for those born between 1935 and 1939.
Source: P. J. Eric Stallard et al., JAMA, vol. 33 / Graphique: let
By 2024, individuals aged 85 to 89 had only a 10% risk of developing dementia.
What Protects Our Brain Health
“These reversals were unexpected and largely ignored,” the researchers wrote. The annual decline is between 2.5 and 3%, with no sign of slowing. But what factors have made the brains of those born in the first half of the 20th century healthier? And will this trend continue for future generations?
The researchers identified two potential factors: a decrease in smoking and an increase in education levels, particularly among women.
Other known risk factors for dementia, better medically treated over the 20th century—such as diabetes, high cholesterol, hypertension, and hearing and vision loss—also play a role. Earlier generations also experienced malnutrition and trauma during the Great Depression and the two World Wars. Subsequently, living conditions improved.
Recent Positive Developments
Smoking rates began to decline in 1965 with increased awareness of the dangers of tobacco. Antidepressants emerged. Starting in the 1970s, alcohol consumption also decreased. In the 1980s, air quality improved, particularly in Switzerland, a key factor for brain health.
These recent advances offer hope that the trend will continue for subsequent generations. The researchers even wrote:
“If this effect persists, the future burden of dementia will be much lower than predicted.”
Today, it’s not just the hearts of seniors that are healthier, but also their brains.Image: Keystone
Precision medicine, still emerging, could soon explain why women are more affected by Alzheimer’s disease. New risk factors could thus be identified and neutralized. This is important, as the researchers write: “At a time when cognitive abilities are more important than ever,” It’s crucial to take action.
Real Risks of a Resurgence
However, other risks have emerged or increased over the past 130 years: obesity and sedentary lifestyles. While diabetes is better treated, it is also more prevalent. Unlike the European countries cited, Japan has not recorded positive trends. In the United States, results vary by group; the African American population has even seen an increase in cases.
Other experts believe that the probability of developing the disease could increase again. Bogdan Draganski, director of the university memory clinic at the University Hospital of Bern, says he does not expect the downward trend in dementia to continue:
“The post-war generation lived in peace and prosperity. Subsequent generations may encounter more problems again. But these are just assumptions.”
Research in this area and data collection are just beginning.
Bogdan Draganski, professor specializing in dementia and neurodegenerative diseases.Image: dr
A Vaccine Already Reduces Dementia Risk
Some believe that one day there will be a vaccine that protects against dementia. As we age, the immune system apparently can no longer eliminate certain harmful proteins from brain structures.
Vaccination can already reduce this risk: the vaccine against chickenpox or shingles (herpes zoster). Two studies conducted in Wales and Australia showed last year that the risk of developing dementia was reduced by 20% in vaccinated individuals. A survey conducted in Canada has just confirmed this. The study only compared the live Zostavax vaccine and unvaccinated individuals. But the Shingrix vaccine showed an even greater effect in a study published in Nature in 2024.
Herpes viruses have long been suspected of promoting dementia. A vaccine is effective, even when the first symptoms have already appeared. The effect is less pronounced in men. American physician Eric Topol summarized these findings on the Substack platform:
“If this vaccine were a drug and reduced the risk of Alzheimer’s by 20%, it would be a major breakthrough.”
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