This study of 92 identical male twins investigated the contribution and interaction of environmental factors and testosterone on hair loss.
A total of 92 identical male twins were followed from 2009 to 2011 and completed a questionnaire in parallel with an analysis of testosterone levels and monitoring of frontal, temporal and vertex hair thinning.
The data showed overall that hair thinning was increased as a function of lower BMI, more children, increased caffeine consumption, history of skin disease and abstinence from alcohol.
Site-specific analysis indicated that frontal hair loss was significantly affected by increased smoking duration and the presence of dandruff.
Temporal hair loss was increased as a function of exercise duration, more than four alcoholic drinks per week and greater spending on hair loss products. It was decreased by daily hat use, and higher BMI and testosterone levels.
Factors that were significantly associated with increased vertex hair loss included abstinence from alcohol, consumption of more than four alcoholic drinks per week, and increased smoking, exercise and stress duration.
The study shows a clear distinction between the genetic and environmental components of hair loss, and that wearing a hat, reducing stress and not smoking might help a man keep more of his hair than his identical sibling.
Gatherwright J, Liu MT, Amirlak B et al. Plast Reconstr Surg 2013; 131: 794e-801e