Monday November 26 2007
Baldness is often hereditary
Smoking has been linked to male hair loss, reported The Sun and other newspapers. Smoking “may help to make men prematurely bald”, the newspaper said. The Independent stated that a “study in Asian men, renowned for hanging on to their hair compared with follically-challenged Europeans … found puffing on cigarettes can hasten male hair loss”. This was even the case when other factors, such as their age and family history of baldness, were taken into account.
The newspaper story is based on a study in Taiwanese men which suggests a link between smoking and baldness independent of other factors. As the results conflict with other studies, more research would be helpful. The effects of smoking upon heart, vascular and lung health, to name just a few, are more established reasons to give up smoking, than whether or not it may reduce the chances of going bald.
Where did the story come from?
Drs Lin-Hui Su and Tony Hsiu-Hsi Chen from the Far Eastern Memorial Hospital and the National Taiwan University conducted this research. There is no information given about sources of funding. It was published in the (peer-reviewed) medical journal: Archives of Dermatology.
What kind of scientific study was this?
The study was a cross-sectional study of men in Tainan County in Taiwan. The researchers were interested in determining how common male pattern baldness was in men in Taiwan. As a secondary aim of their study, they looked at whether smoking was associated with hair loss. This has already been looked at by three previous studies, and there have been conflicting results.
Men were selected from a larger ongoing study using a household register of the county, and 929 were invited to join this study; 740 of whom agreed to participate. A public health nurse (trained by a dermatologist) rated the degree of their hair loss using a well-known scale – the Norwood scale. The men were interviewed to find out at what age their baldness began, as well their smoking status (never, quit or current smokers) and details about their habit (i.e. how often they smoked, how much they smoked, when they started smoking). Body weight, height, waist circumference and hip circumference were also measured, as was blood pressure. Blood tests were taken to check for blood glucose and cholesterol levels.
The participants were also asked other questions including their age, history of chronic diseases, timing of puberty, socioeconomic factors, alcohol and drug use, and family history of baldness. The researchers analysed the data to see how common baldness was among the population. They then looked at the relationship between smoking and baldness, taking into account age and family history of baldness.
What were the results of the study?
The researchers found that the prevalence of baldness increases with age and that the results were comparable with Korean populations but lower than in men from Singapore. The researchers also found that compared with men who said they “never” smoked, those who said they were current smokers or had once smoked but now quit, were nearly twice as likely to have moderate or severe hair loss. When the researchers broke this down further (separating out the quitters from those who currently smoked), they found that current smokers who smoked more than 20 cigarettes per day were more than twice as likely to have moderate or severe hair loss than people who never smoked. However, people who smoked less than 20 cigarettes per day and those who once smoked but had now quit did not appear to be at increased risk of baldness.
Other factors which seemed to be related to moderate or severe baldness were intensity of smoking (which they defined as the amount smoked per day multiplied by the duration of smoking), and dislipidemia (a disruption in the regulation of fats in the blood). The study also found that the risk of moderate or severe baldness increased with the degree of relationship for family history, i.e. those reporting that a first degree relative (for example a father or sibling) also had male pattern baldness were more likely to go bald than those with more distant relatives who had hair loss. People with first degree relatives with baldness were 13 times more likely to have moderate or severe baldness themselves, than those with no family history.
What interpretations did the researchers draw from these results?
The researchers concluded that their research demonstrated a positive link between smoking and baldness. As expected, the prevalence of baldness increased with advancing age. The researchers put forward some theories as to why smoking may lead to baldness. Smoking may damage the vessels at the very bottom of the hair follicle, they suggested, or may damage the DNA in the hair follicle.
What does the NHS Knowledge Service make of this study?
This is a cross-sectional study and as such, it cannot definitively establish that one factor causes another. When interpreting the results, be aware that there may be factors that the researchers have not measured that could be linked to both smoking and hair loss. However, the study has demonstrated a relationship between smoking status and hair loss that seems to be independent of family history and current age, both of which are already known to be linked to baldness.
- There is some genetic factor involved in male pattern baldness. This study illustrates the strength of this by finding that people with a first degree relative with baldness are 13 times more likely to be bald than people without relatives with baldness.
- The study was carried out in a group of Taiwanese men and as such the findings may not be directly applicable to men in other cultural groups. There is a recognised contribution of ethnicity to baldness with lower prevalence being seen in Asian, Native Americans and African American men in comparison to Caucasian men. The details behind these differences are not well understood.
- There are a host of other more established reasons to give up smoking, and this study may be touching on yet another one.
- The results of this research are in conflict with some other studies, so more research on this subject would be useful.
Sir Muir Gray adds...
Another nail in the coffin of the cigarette; even the rumour of this finding will have an impact, whatever its validity.