What is alopecia areata?

Alopecia areata is recognized as an autoimmune condition that leads to hair loss characterized by the development of one or more round patches of hair loss on the scalp or other areas of the body. The condition occurs when the immune system mistakenly attacks the hair follicles, leading to hair falling out in defined patches. This description aligns perfectly with the understanding of alopecia areata, making it the correct choice.

In contrast, hair thinning due to aging refers to a gradual reduction in hair density and is not typically characterized by patchy loss. Complete baldness, often referred to as alopecia totalis, involves total hair loss over the entire scalp and sometimes the body, and is considered a more extensive form of hair loss than alopecia areata. Excessive hair growth, or hirsutism, does not relate to hair loss scenarios and instead deals with having more hair than is typically expected for a given gender. Each of these other conditions is distinct from the patchy loss seen in alopecia areata, emphasizing why patchy loss is the definition that fits this alopecia type.