Actress Jada Pinkett Smith

Alopecia tends to run in families. Total hair loss affecting the entire body can happen, but is rare. The condition can also cause dents and ridges in fingernails and toenails, but affected people are otherwise healthy. Alopecia is a broad term that refers to any form of hair loss, said Dr. Angela Lamb, a board-certified dermatologist at Mount Sinai in New York City. It can have many causes. Some people — especially men ­— lose scalp hair with age because of changes in hormones known as androgens, she said, and that is considered a form of alopecia. A type of hair loss common in the Black community is traction alopecia, which occurs when hair has been pulled tight for too long.