Smoking may hasten ageing, genetic data suggest

A study presented at ERS 2023 revealed a potential causal relationship between smoking and length of telomeres, which are the DNA-protein complexes protecting the ends of chromosomes.

“The gradual reduction of telomeres can cause somatic cells to undergo senescence, apoptosis, or oncogenic transformation, thereby impacting an individual’s health and lifespan,” said Assistant Professor Siyu Dai from the School of Clinical Medicine, Hangzhou Normal University, China. “Our results suggest that current or ever smokers face a higher risk of ageing than never or nonsmokers.”

Both current and ever smokers had shorter leukocyte telomere lengths (LTL) than never smokers (ß, -0.29 and -0.16 vs 0.21). The association between current smoking and shorter LTL was statistically significant (p=0.013). Despite the negative trend, the link between former smoking and shorter LTL failed to achieve statistical significance (p=0.221). Never smoking was positively associated with LTL (p<0.0001). [ERS 2023, abstract OA4230]

Higher pack years of smoking was also significant tied to shorter LTL (ß =-0.08; p=0.008). This means that individuals who smoked more cigarettes had significantly shorter LTL.

“In summary, smoking may cause LTL shortening, and the more cigarettes smoked, the stronger the shortening effect,” Dai explained in a press release.

Other variables tied to shorter LTL were second-hand smoke exposure (ß, -0.24) and difficulty not smoking for a day (ß, -0.08).

Marker of biological ageing

“LTL is a proposed marker of biological ageing. Comparatively shorter LTL is associated with shorter natural life span limit in humans,” said Dai. Evidence shows that individuals with shorter LTL have increased mortality risks due to heart or infectious disease.

Mendelian randomization was conducted to identify a causal relationship between smoking status, smoking quantity, passive tobacco smoking, and LTL by using single nucleotide polymorphisms. The researcher team used data on about half a million participants from the UK Biobank.

A time to quit

“Our study shows that smoking status and cigarette quantity can lead to LTL shortening, which is an indicator of tissue self-repair, regeneration, and ageing. In other words, smoking can accelerate the process of ageing, while quitting may considerably decrease the related risk,” said Dai.

“Our study adds to evidence showing that smoking causes ageing. As there are clear health benefits of smoking cessation, it is time to include cessation support, as well as treatment into daily clinical management to help us to create a smoke-free environment for the next generation,” Dai continued.

The researchers are set to carry out further investigation to ascertain their findings. Plans are also underway to corroborate the effects of passive smoke exposure on tissue self-repair, regeneration, and ageing.

“The study … shows a clear association between smoking and reduced TL … It will be interesting to see what the researchers have found in relation to the effects of passive smoking on TL,” commented Professor Jonathan Grigg, Chair of the ERS Tobacco Control Committee, who was not affiliated with the study.