Is it possible to reverse human ageing?

The eternal question, the fantasy of so many novels and movies!

As cultures and societies, we accept that ageing is part of life. We expect our hair to give way to greys, as we reach our 50s and 60s. We accept that with advancing years, we’re more likely to get illnesses of ‘old age’. But this might not always be the case! 

A small study  in California, published in 2019, suggests that it may be possible to reverse human ageing. Now, don’t get very excited! This is a very small study with a number of limitations (I’ll go through these later), but if its findings are repeated in the future, then this might just be the beginning of a revolution in the science of human ageing and longevity!

What was the study about?

The clinical trial, led by Dr Fahy, was called Thymus Regeneration, Immunorestoration and Insulin Mitigation (TRIIM). Its main aim was to see if it’s possible to prevent or reverse ageing of the immune system, through restoring the thymus. 

What is the thymus?

Before we go further, let’s talk a bit about the thymus and what it does. The thymus is a gland (an organ which makes certain chemical substances) that sits in the chest behind the breastbone. It makes a certain type of white blood cells called T cells that help fight off infection and cancer. But this gland starts to shrink after puberty and gradually gets replaced with fat, as we get older. This is linked to a decline in T-cell numbers and is thought to contribute to a weaker immune system in older people.

How was the study done?

The research tested nine healthy white men between the ages of 51 and 65, over a period of 12 months. The volunteers used growth hormone given as an injection, to stimulate the thymus. But because this hormone can cause diabetes, two other agents – metformin and (dehydroepiandrosterone) DHEA – were added for their anti-diabetic effect.

What did the study find?

Regenerating the thymus & the immune system

The study showed that the thymus can be regenerated. Fat was replaced by thymus tissue in seven out of the nine participants by the end of the study. But did this regeneration translate into T-cells being produced again? The answer is yes! Participants produced new T-cells and showed other clinical signs of immune system rejuvenation.

Winding back the clock

The most surprising finding from the study – and the outcome which had grabbed headlines – is that ‘biological age’ of participants was significantly reversed. 

Biological age tracks how your cells and body have changed throughout your life. It can be determined using epigenetic clocks. These clocks measure marks on a person’s DNA and can tell you how biologically old or young you are, more accurately than counting your birthdays.

The biological age of participants was measured using the ‘Horvath aging clock’, called after the scientist who pioneered this type of technology. After one year of treatment, the biological age of participants was reduced by 2.5 years. And it seems there was some lasting benefit! Six months after finishing treatment, the participants still had one year shaved off their biological age.

What are the limitations of this study?

This was a very small trial, with no control group. It did not include women or minorities and was too small to determine side effects.

A control group, in which participants don’t receive the treatment being tested, is important: It helps establish if the effect experienced by participants (in this case a reduced biological age) is due to this treatment. Because there was no control group in TRIIM, we don’t know which agent caused the beneficial effect on biological age – metformin is already being studied for its own potential effect against age-related diseases.

Growth hormones are only available on prescription. They are prescribed to treat growth problems and deficiencies and can have a number of side effects. Given the misuse potential of growth hormones, how practical would it be to make them more widely available as anti-ageing therapies in the future?

A look into the future

TRIIM was an interesting but small study, so it’s currently being replicated in a larger study: TRIIM-X.

TRIIM-X is a randomised (where participants are divided by chance into separate groups) clinical trial, with a control group. It has 85 participants, and includes both men and women, different ethnicities and has a wider age range (40-80 years of age). 

We eagerly await the results of the study, as it may turn out that ageing backwards might not be as far-fetched as we once thought! Watch this space!


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