AsianScientist (Apr. 14, 2023) – Our age reflects in our DNA. Shortening telomeres—the ‘protective caps’ at the ends of our chromosomes—can indicate cellular aging. A new study from South Korea suggests that it can also be useful for spotting warning signs of late-life depression and cognitive decline in older adults who might still appear relatively healthy. The study’s findings were published on the cover of Aging.
As people age, they become more susceptible to depression and cognitive decline, making early diagnosis crucial in effectively delaying disease progression and minimizing disability. Telomeres, being repetitive DNA sequences that chip away each time a cell divides, are ‘molecular clocks’ that can tell us how quickly our cells are aging. Although telomere shortening has been associated with severe depression and cognitive impairment in older adults, it remained unclear if it could also reflect early signs of these conditions and be potentially used for an earlier diagnosis.
Researchers from Hanyang University and Inha University in South Korea found that the answer was lying in their earlier SUPERBRAIN study which was initially used to explore lifestyle interventions for protecting the brain health of older adults. The randomized controlled trial of 137 relatively healthy adults took measurements from questionnaires and blood sample analyses once at baseline and again after six months of follow-up.
After performing statistical analyses, the team identified that early subjective depressive symptoms and cognitive complaints were in fact associated with a relatively shorter telomere length. The results showed that an increase of one point on the geriatric depression scale and cognitive interview scores resulted in a reduction of approximately 0.06 and 0.11-0.14 kilo base pairs of telomere length, respectively.
Moreover, the team found that the levels of interleukin (IL)-6, a blood biomarker linked to geriatric diseases, were also associated with telomere length, with every one-point increase in IL-6 levels resulting in an approximate shrinkage of 0.08-0.09 kilo base pairs of telomere length.
“We believe that IL-6, an inflammatory cytokine, plays an important role in the relationship of shortening TL with early subjective depressive mood and cognitive complaints,” said the researchers.
Evidence suggests that inflammation pathways play a crucial role in linking accelerated cellular aging with depression and cognitive decline. They are the body’s natural response to injury or infection, triggering the release of chemicals known as cytokines that cause damage. Chronic, low-grade inflammation can gradually erode telomeres through oxidative damage. While cells with shortened telomeres can produce more inflammatory cytokines like IL-6, this sets off a dangerous cycle that exacerbates structural and functional changes in the brain and leads to cognitive decline and mood disorders like depression.
Although these findings have important implications, the researchers acknowledge that the limitations of the study need to be addressed to confirm them. For example, the present study was not primarily designed to test the relationship between telomere length and early signs of depression and cognitive impairment. Since this was only a feasibility study, a larger randomized controlled trial study would be needed to reaffirm these findings. Additionally, extending the period between the two measurements of telomere lengths would be necessary to gain a better understanding of how this process works long-term.
“Although the results will need to be verified through a large-scale RCT in the future, we believe that our findings will help prevent and treat depression and cognitive impairment in the healthy elderly,” said the researchers from the study.
Source: Hanyang University ; Image: Shelly Liew/ Asian Scientist Magazine
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