Depressive symptoms and memory loss in older adults linked to telomere shortening: ScienceAlert

There’s a tiny, slow-burning “fuse” attached to the ends of all of our chromosomes, and as we naturally age, each of our cells loses more and more of this lifeline.

South Korean researchers have now shown that this fuse, known as the telomere, is unusually short in the cells of older people who are relatively healthy but have noticed early signs of depressive symptoms and cognitive decline, such as memory loss.

The randomized controlled trial presents further evidence for the telomeric aging hypothesis, which posits that all cells reach a point where they can no longer divide and replicate.

Telomeres are essentially the “molecular clocks” that tick to that final zero, and their countdown seems to be accelerated by chronic stress and possibly depression.

Telomeres are repetitive sequences of DNA that form protective “caps” at the ends of a cell’s chromosomes. Each time the cell divides and replicates, the telomeres shorten a little and their protective qualities diminish.

When the telomeres finally reach their end, the cell stops dividing and enters a zombie-like state.

The hypothesis is that if the body’s recycling system doesn’t eliminate these zombie cells, the undead can form an “army” that can contribute to disease just about anywhere in the body.

Whether or not you accept this hypothesis, it is clear that telomere shortening is closely linked to aging, not only for the cell but for the whole organism.

Numerous studies have shown that telomere length in the elderly is closely linked to cognitive impairment and depression.

The physical toll that chronic depression can have or its links to inflammation has been used to explain why aging is accelerated in the brains and telomeres of some older people.

And new research from South Korea confirms this interpretation, even for what could be early depression.

The trial included 137 volunteers aged 60 to 79. Ultimately, those who showed symptoms of depression and complained of cognitive problems were more likely to have shorter telomeres.

These shorter telomeres were also linked to increased levels of interleukin-6 (IL-6), which can act as a pro-inflammatory cytokine, as well as an anti-inflammatory myokine in the blood.

“Based on our findings, we believe that telomere length shortening in the elderly is not only associated with advanced depression, but also with early depressive symptoms,” write neurosurgeon Myung-Hoon Han of Guri Hospital of Hanyang University and his colleagues.

“Shortening of telomere length is associated with increased IL-6 levels in older adults, and we speculate that IL-6 may be a cytokine implicated in depression from early stages to advanced depression. .”

Chronic inflammation has become a major suspect in many age-related diseases in recent years, including Alzheimer’s disease.

Today, depression is known to significantly increase the risk of developing Alzheimer’s disease, and increased inflammatory markers like IL-6 have been linked to dementia.

“The precise mechanism underlying the correlation of shorter (telomeres) with depression, cognitive decline and inflammatory cytokines remains unclear,” admit the researchers.

But that’s just a correlation, and it doesn’t tell scientists which way cause and effect go. In all likelihood, however, these are intersecting two-way streets.

Cells that have shortened telomeres, for example, are more likely to secrete pro-inflammatory cytokines like IL-6. Meanwhile, chronic low-grade inflammation appears to shorten telomeres at a faster rate.

“This repeated process can cause cumulative structural and functional changes in the brain, leading to cognitive impairment and mood disorders, including depression,” the researchers explain.

The results of the recent randomized trial will need to be replicated in larger cohorts, but the authors hope their findings could help predict depression in older people before it takes its toll.

The study was published in Aging.

Leave a Comment