The Contribution of Endogenous and Exogenous Factors to Female Alopecia

The study from 11 years ago involved 98 identical female twins and aimed to assess the impact of environmental factors and testosterone levels on female androgenic alopecia. It found that environmental factors such as marital status, sleep duration, stress, smoking, income, hat use, and medical history (diabetes, polycystic ovarian syndrome, hypertension) were linked to increased hair loss in different scalp regions. Higher testosterone levels were associated with more temporal and vertex hair loss. Genetics was the only predictor for vertex hair loss, while age was not significant. Protective factors included sun protection and caffeine consumption, which were associated with less vertex hair loss. Conversely, a history of skin disease and lack of exercise were related to increased hair loss. The study concluded that both genetic and nongenetic factors significantly contribute to female hair loss, with the latter including lifestyle and medical history. The study's limitations were its reliance on self-reported data and a relatively small sample size, but the use of identical twins helped control for genetic variability.