Alopecia aerate is a disease of scalp that is characterized by loss of hair in round spots. In 1-2% of the cases may have complete hair loss called as Alopecia totalis. Characteristic feature is Well-circumscribed, circular areas of hair loss, 2–5 cm in diameter. Immune cells develop an inflammatory process around germinative zones of the hair follicles. This inflammatory process destroys the hair follicles and subsequently hair is lost. Though, alopecia aerate is non-life threatening, non-contagious and non irritant, it can cause great emotional and psychosocial distress to patients.
The exact pathophysiology of alopecia aerate remains unknown. The most widely accepted hypothesis is that Alopecia aerate known to be T- lymphocytes –mediated autoimmune disease that is likely to occur in genetically predisposed individuals.
Symptoms Alopecia areata
It starts with a small bald spot on the scalp caused due to hair loss. Sometimes when the hair on the boundary of the bald spot is pulled  it comes out easily without pain. Sometimes the bald spots can be seen on different parts of the scalp or body.
Treatment
There is no cure or approved drug for alopecia aerate. Some doctors recommend the combination of drug therapy which includes skin sensitizers, corticosteroids, some hair promoters, immunomodulator and corticosteroid injection and cream. It is recommended to Consult a health care professional for the best treatment for you. Self medication is always dangerous as these medicines can produce lots of side effects. Though these treatments may promote hair growth, it may not stop the hair loss.
Causes
The exact cause of Alopecia aerate is not clearly understood, but it is understood that it is an immune mediated destruction. The white blood cells particularly the T-lymphocytes attack the germinating cells in the hair follicles. The affected hair follicles become small and significantly slow down hair growth. The good part of this is, the immunes system do not attack the stem cells that support the follicle that the cells do. So there are all chances of re-growth of hair. It is also found in people how they undergo  intense physiological stress
Prevention
Scientists do not know exactly why this is happening. It is suspected that a combination of genes may be predisposing factor. So it is very difficult to say, how it can be prevented.  In those who are genetically predisposed, some factors trigger the condition perhaps due to stress. Anti-stress exercises along with the above mentioned treatment will be more helpful for controlling the condition.
Diagnosing
Alopecia aerate can be diagnosed by analyzing the pattern at the hair loss. If the patch of hair loss is expanding, the doctor may pull out a few hair. These hair will be examined under a microscope. In some cases skin biopsy is performed to confirm the disease.
Prognosis
The hair will regrow with or without treatment, but the disease may re appear. It is difficult to predict when the hair might regrow or fall off again. The course of the disease differs from person to person. Some people loose just a few patches of hair initially, and then the hair regrows, and the condition never recurs. Other people continue to loose and regrow hair for many years. A few loose all the hair on the scalp, face, and body. Even in those who loose all their hair, the possibility for full regrowth remains.
In some, the initial hair regrowth is white, with a gradual return of the original hair color. In most, the regrown hair is ultimately the same color and texture as the original hair.