Researchers involved in a large-scale study of more than 356,000 individuals in the United Kingdom have found that shorter telomeres—protective caps on chromosomes—may indicate increased risk for stroke, dementia, and late-life depression. The research team, who presented these findings at the American Stroke Association's International Stroke Conference 2025, noted that individuals with the shortest leukocyte telomere length had significantly higher risks of developing these age-related brain conditions.
Specifically, compared to those with longer telomeres, individuals with the shortest telomeres demonstrated an 8% higher risk of stroke, a 19% higher risk of dementia, and a 14% higher risk of late-life depression. Overall, these individuals showed an 11% higher risk of developing at least one of these conditions.
"No studies have examined the impact of leukocyte telomere length on a composite outcome of age-related brain diseases that include stroke, dementia, and late-life depression," said study investigator Tamara N. Kimball, MD, a postdoctoral research fellow at Massachusetts General Hospital. "All three conditions are linked to cerebral small vessel disease, a condition associated with aging and accumulation of vascular risk factors."
The study, which tracked participants for a median of 12 years, also revealed that lifestyle factors might mitigate risks associated with shorter telomeres. Individuals with higher Brain Care Scores, indicating healthier lifestyle choices, showed no increased risk of age-related brain diseases despite having shorter telomeres.
"This suggests that adopting healthier lifestyles and improving modifiable risk factor profile may lower the negative effects of shorter leukocyte telomeres. In short, it is never too late to start taking better care of your brain," Dr. Kimball noted.
The research team employed Mendelian randomization, a statistical method to explore causality, finding no evidence that telomere length directly causes these conditions. Rather, as Dr. Kimball explained, "Leukocyte telomere length may act more as a reflective marker of underlying biological processes and cellular stress that precede these age-related diseases."
The study's limitations include its focus solely on participants of European ancestry and baseline-only measurements of telomere length. Additionally, the researchers noted that while leukocyte telomere length serves as a proxy for overall telomere length, it may not represent telomere length in other cell types.
Costantino Iadecola, MD, FAHA, Director of the Feil Family Brain & Mind Research Institute at Weill Cornell Medicine, who was not involved in the study, commented on its implications: "Recent research shows that different parts of the body age at different rates, each with its own 'aging clock.' Evidence suggests that longer telomeres in white blood cells are linked to a lower risk of major brain diseases related to aging. This indicates a strong link between the aging clock of the immune system and the brain."
The findings remain preliminary until published in a peer-reviewed scientific journal.
