Heavy smoking may have a causal effect on facial ageing, 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 recognising several known adverse effects such as on lung health, the research also found heavy smoking could influence appearance.
The study, published in PLOS Genetics today, 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 e.g. on lung function.
They also identified an interesting potential effect of heavier smoking on more facial ageing.
Their finding adds 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.
By showing that the approach works, it could be used to search for the effects of other exposures, such as alcohol intake.
Dr Louise Millard, Vice Chancellor’s Research Fellow in the Bristol Medical School: Population Health Sciences (PHS) who led the research, said: “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.
We searched across thousands of traits to identify those that may be affected by how heavily someone smokes.
As well as identifying several known adverse effects such as on lung health, we also identified an adverse effect of heavier smoking on facial aging.”
Mendelian randomization is a technique that uses genetic variation in a person’s DNA to help understand the causal relationships between risk factors and health outcomes – here whether how heavily someone smokes causally affects health outcomes.
The research team found their approach worked, as their results included several known effects of heavier smoking e.g. on lung function.
They also identified an interesting potential effect of heavier smoking on more facial ageing.
However, Mendelian randomization is biased if the genetic variant also affects the outcome via other pathways.
The research team used additional information – that the effect of heavy smoking only occurs in people who actually smoke – to overcome this problem.
By testing associations in ever and never smokers separately they were able to assess whether the genetic variant affects an outcome via smoking or another pathway. If the effect is at least partially via smoking heaviness, the researchers would expect the effect to differ in ever versus never smokers, and this would suggest that smoking causally influences the outcome.
Further work is needed to find out whether being told that smoking could affect appearance is an effective strategy for smoking prevention or stopping.
Age-related skin changes are caused by a combination of intrinsic chronological processes and extrinsic factors. Ultraviolet (UV) exposure is the main extrinsic cause;1–3 other reported factors include tobacco use,4–7 high alcohol intake,4 air pollution,3 low body mass index (BMI),5,6 and lower socioeconomic status.5
Free radicals generated by smoking damage repair mechanisms and reduce extracellular matrix turnover (e.g., collagen and elastin synthesis), leading to premature signs of skin aging.3,8 Smoking also causes cutaneous microvascular constriction that increases in relation to the duration and amount of exposure.9
Alcohol consumption impairs the skin’s antioxidant defense system by decreasing dermal carotenoid concentrations.10
Alcohol also causes peripheral vasodilation,11,12 which can lead to dilated facial capillaries.
Social perceptions and value judgments are often based on appearance.
Wrinkles; under-eye puffiness; uneven skin tone; and volume loss around the eyes, midface, and lips add to the perception of increased age.5,13
Previous studies have shown varying associations exist between tobacco or alcohol use and skin photoaging,5,14 wrinkling,6,15–18 or facial aging in general.13,19
However, these studies were generally conducted in single countries and involved relatively small study populations (i.e., a few hundred participants or fewer).
Few data are available on the patterns and specific characteristics of facial skin- and volume-related aging from large, globally dispersed populations of women who smoke and drink alcohol compared to those who abstain.
Knowledge of premature facial aging patterns in women with a history of smoking and/or high alcohol consumption helps practitioners provide evidence-based advice on lifestyle modifications to help patients preserve their facial appearance. T
his analysis of a cross-sectional, Internet-based survey of more than 3,000 women from the United States (US), Australia, Canada, and the United Kingdom (UK) was conducted to determine the patterns of clinical signs of facial aging associated with tobacco and alcohol use.
Study population. A total of 10,823 people responded to the survey invitation between December 2013 and February 2014; their disposition is summarized in Figure 1.
This subanalysis, conducted in 2016 and 2017, included data from 3,267 women: 1,569 (48.0%) from the US, 591 (18.1%) from Canada, 588 (18.0%) from Australia, and 519 (15.9%) from the UK.
The relative proportions of survey respondents were similar in each age band. Participant demographics and smoking and alcohol consumption habits of the participants are summarized by age group in Appendix 1 and Figure 2. The proportions of women with different Fitzpatrick Skin Types were similar across all age groups (p=0.0642; Appendix 1).
Overall, 1,166 women (35.7%) were current or former smokers (Appendix 1), mostly of cigarettes (1,144/1,166; 98.1%).
Women aged 50 to 75 years had the longest smoking histories (Appendix 1; Figure 2A), but the largest proportion of current smokers (131/494; 26.5%) was aged 40 to 49 years. Just over half of respondents (1,727; 52.9%) reported that they drank alcohol (Appendix 1).
Of these, 1,499 (86.8%) reported consuming one drink or fewer per day (i.e., 0–7 drinks per week, defined as “consuming alcohol in moderation” in the 2015–2020 Dietary Guidelines for Americans25), and 226 women (13.1% of the drinkers) consumed eight or more drinks per week (defined as “heavy drinking”25).
Women aged 18 to 29 years composed the highest proportion of alcohol drinkers, but the greatest proportion of heavy drinkers was aged 50 to 69 years (Figure 2B). Wine or champagne were the most commonly consumed alcoholic beverages by women of all age groups (Figure 2C).
Effect of smoking. Linear regression showed that current smokers had more severe signs of aging than did nonsmokers, and the associations with increased forehead and glabellar lines, under-eye puffiness, nasolabial folds, oral commissures, and reduced lip fullness were statistically significant (Appendix 2).
Being a former smoker was significantly associated with more severe aging of all facial features than in nonsmokers, except for midface volume loss and visible blood vessels on the cheeks (p≤0.025; Appendix 2).
Figure 3A summarizes the facial features for which statistically significant associations between smoking status and increased aging severity were identified. Comparisons between current and former smokers revealed no statistically significant differences in facial aging severity for any feature (data not shown).
FIGURE 3.
Facial features for which the aging severity are significantly associated (p<0.05) with smoking or alcohol consumption by linear regression analysis (Appendices 2–4), after controlling for age, race, body mass index, and country, according to smoking status (A), smoking pack-year history (B), and alcohol consumption level, (C) respectively
When smoking history was analyzed by pack-years, forehead and glabellar lines, under-eye puffiness, tear troughs, nasolabial folds, and deep oral commissures were significantly more likely to be present than in nonsmokers, even in women with the shortest smoking history (1– 10 pack-years; p≤0.018; Appendix 3 and Figure 3B).
Significantly greater loss of midface volume and lip fullness were associated with an 11- to 20-pack-year history (p≤0.032), while crow’s feet and perioral lines were only significantly associated with a smoking history of more than 20 pack-years (p≤0.0002).
In general, the mean severity over time of the analyzed features increased with smoking history, although observed differences were generally rated with one point or less on the photonumeric severity scales (Figure 4A).
When comparing smoking pack-year history categories, only glabellar lines showed significant differences in severity between categories in smokers: women with 11-to-20 and 1-to-10 pack-year smoking histories had progressively less glabellar line severity than did those with greater-than-20 pack-year histories (p≤0.0089).
Effect of alcohol use. Regression analyses suggested a relationship between alcohol use and aging severity that was statistically significant for under-eye puffiness, midface volume loss, and blood vessels on the cheeks (Pr > F < 0.05 in Appendix 4).
In heavy drinkers (i.e., those who consumed eight or more drinks per week25), seven facial features were significantly associated with an appearance of more severe aging than in women who did not consume alcohol (p≤0.042; Appendix 4 and Figure 3C).
However, drinking in moderation was only significantly associated with increased under-eye puffiness (p=0.026) and midface volume loss (p=0.041). In general, mean severity over time of the features analyzed increased to a greater extent in heavy drinkers (Figure 4B). However, comparisons between moderate and heavy drinkers revealed no significant differences in aging severity for any facial feature except visible blood vessels, which were more severe in heavy drinkers (p=0.007).
Linear regression analyses were also conducted to investigate whether alcoholic beverage type would impact facial aging differently. No specific beverage type was identified as being associated with an increased severity of any facial feature, although under-eye puffiness was associated with drinking a combination of beverages (p=0.001) and increased cheek blood vessels were seen among wine drinkers (p=0.0005).
When interactions between smoking history and alcohol use and their impact on aging were investigated using linear regressions, the impact of pack-years on aging severity was not dependent on alcohol use and vice versa.
Source:
University of Bristol
Media Contacts:
Caroline Clancy – University of Bristol
Image Source:
The image is in the public domain.
