Male pattern baldness is directly linked to levels of dihydrotestosterone (DHT). Follicles are sensitive to this substance which can cause an imbalance in the follicle, resulting with them shrinking, hair thinning and eventually will no longer grow back.
Females can also begin to lose their hair due to hormones (female pattern hair loss). Changes in the levels of androgens (male hormones) e.g. after reaching menopause, can cause many women’s hair to begin thinning.
Physical trauma and emotional stress can both lead to hair loss in men and women. Though this form of hair loss can quite often be reversed after a period of recovery, it can at times lead to permanent hair loss in time.