A curvilinear relationship between hair loss and mental rotation and neuroticism: a possible influence of sustained dihydrotestosterone production

Hairline measurements and ratings of fatherʹs hair loss were used in a multiple regression to predict hair loss in 181 males. This was hypothesised to measure the effects of cumulative dihydrotestosterone (DHT) on hairline. Participants were also given a test of mental rotation, and rated their own anger and neuroticism. They were then divided into five groups according to level of hair loss. Significant effects were found for mental rotation and neuroticism. Mental rotation was an inverted-U function of the extent of hair loss, indicating a curvilinear relationship between DHT and spatial cognition. Neuroticism also demonstrated an inverted U relationship, but this function was less clear visually and statistically. The self-rated measures of anger were not affected by DHT. One implication of the effect of mental rotation as a function of hair loss is that long-term high or low levels of DHT could impair spatial cognition in men.