Heavy smoking may have a causal effect on facial aging, according to new research led by the University of Bristol.

The study searched across 18,000 traits from the UK Biobank cohort to identify those that may be affected by how heavily someone smokes. As well as recognizing several known adverse effects such as on lung health, the research also found heavy smoking could influence appearance.

The study, published in PLOS Genetics, was led by the University’s MRC Integrative Epidemiology Unit (IEU) and also supported by the NIHR Bristol Biomedical Research Centre (BRC).

The researchers wanted to demonstrate a new approach that could be used to systematically test for causal effects across thousands of outcomes, by combining two existing methods: the Mendelian randomization phenome-wide association study approach and gene-by-environment interaction tests. To test their new method, the Bristol team searched for the effects of heavy smoking using the UK Biobank cohort.

The research team found their approach worked, as their results included several known effects of heavier smoking. They also identified a potential effect of heavier smoking on more facial aging.

The findings add to evidence that found heavier smoking affects facial attractiveness and the amount of wrinkling, which might be reasons to encourage someone to stop smoking or deter them from starting in the first place, according to the researchers.

“We proposed a novel approach that could be used to search for causal effects of health exposures, and demonstrated this approach to search for the effects of smoking heaviness,” lead author Louise Millard, vice chancellor’s research fellow in the Bristol Medical School: Population Health Sciences (PHS), says in a statement.