Asian Scientist (April 14, 2023) – Our age is reflected in our DNA. The shortening of telomeres, the “protective caps” on the ends of our chromosomes, can indicate cellular aging. A new study from South Korea suggests that it may also be useful for spotting warning signs of depression and cognitive decline in older adults who may still appear relatively healthy. The study findings were published on the cover of Aging.
As people age, they become more susceptible to depression and cognitive decline, making early diagnosis crucial to effectively delay disease progression and minimize disability. Telomeres, which are repetitive sequences of DNA that break each time a cell divides, are “molecular clocks” that can tell us how fast our cells are aging. Although telomere shortening has been associated with serious depression and cognitive decline in older adults, it was not clear if it might also reflect early signs of these conditions and if it could be used for earlier diagnosis.
Researchers from Hanyang University and Inha University in South Korea found that the answer lay in their previous SUPERBRAIN study which was initially used to explore lifestyle interventions to protect brain health in older adults. The randomized controlled trial of 137 relatively healthy adults took measurements from questionnaires and analyzed blood samples once at baseline and again after six months of follow-up.
After performing statistical analyses, the team identified that subjective early depressive symptoms and cognitive complaints were in fact associated with relatively shorter telomere length. The results showed that a one-point increase in the Geriatric Depression Scale and Cognitive Interview scores resulted in approximately 0.06 and 0.11-0.14 kilobase pair reductions in telomere length. , respectively.
In addition, the team found that levels of interleukin (IL)-6, a blood biomarker related to geriatric diseasesthey were also associated with telomere length, with each one-point increase in IL-6 levels resulting in an approximate 0.08-0.09 kilobase pair reduction in telomere length.
“We believe that IL-6, an inflammatory cytokine, plays an important role in the association of LT shortening with early subjective depressed mood and cognitive complaints,” the researchers said.
Evidence suggests that inflammatory 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. Low-grade chronic inflammation can gradually erode telomeres through oxidative damage. While cells with shortened telomeres may produce more inflammatory cytokines such as IL-6, this it triggers a dangerous cycle that exacerbates structural and functional changes in the brain and leads to cognitive decline and mood disorders such as depression.
Although these findings have important implications, the researchers acknowledge that limitations of the study need to be addressed to confirm them. For example, the present study was not designed primarily to assess the relationship between telomere length and early signs of depression and cognitive decline. Since this was only a feasibility study, a larger randomized controlled trial study would be needed to reaffirm these findings. Furthermore, it would be necessary to extend the period between the two telomere length measurements to gain a better understanding of how this process works in the 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 decline in the healthy elderly,” the study investigators said.
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Source: Hanyang University; Image: Shelly Liew/Asian Science Magazine
The article can be found at Relationship between telomere shortening and early subjective depressive symptoms and cognitive complaints in older adults.
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