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Amnesia refers to the loss of memories, such as facts, information and experiences. Though having no sense of who you are is a common plot device in movies and television, real-life amnesia generally doesn’t cause a loss of self-identity. Instead, people with amnesia — also called amnestic syndrome — are usually lucid and know who Read more…

Amenorrhea (uh-men-o-REE-uh) is the absence of menstruation — one or more missed menstrual periods. Women who have missed at least three menstrual periods in a row have amenorrhea, as do girls who haven’t begun menstruation by age 15. The most common cause of amenorrhea is pregnancy. Other causes of amenorrhea include problems with the reproductive Read more…

Ameloblastoma is a rare, noncancerous (benign) tumor that develops most often in the jaw near the molars. Ameloblastoma begins in the cells that form the protective enamel lining on your teeth. Ameloblastoma occurs in men more often than it occurs in women. Though it can be diagnosed at any age, ameloblastoma is most often diagnosed Read more…

Ambiguous genitalia is a rare condition in which an infant’s external genitals don’t appear to be clearly either male or female. In a baby with ambiguous genitalia, the genitals may not be well-formed or the baby may have characteristics of both sexes. The external sex organs may not match the internal sex organs or genetic Read more…

Alzheimer’s disease is a progressive disease that destroys memory and other important mental functions. At first, someone with Alzheimer’s disease may notice mild confusion and difficulty remembering. Eventually, people with the disease may even forget important people in their lives and undergo dramatic personality changes. Alzheimer’s disease is the most common cause of dementia — Read more…

Allergies occur when your immune system reacts to a foreign substance — such as pollen, bee venom or pet dander — that doesn’t cause a reaction in most people. Your immune system produces substances known as antibodies. Some antibodies protect you from unwanted invaders that could make you sick or cause infection. When you have Read more…

Alcoholic hepatitis is inflammation of the liver caused by drinking alcohol. Alcoholic hepatitis is most likely to occur in people who drink heavily over many years. However, the relationship between drinking and alcoholic hepatitis is complex. Not all heavy drinkers develop alcoholic hepatitis, and the disease can occur in people who drink only moderately. If Read more…

Alcohol use disorder (which includes a level that’s sometimes called alcoholism) is a pattern of alcohol use that involves problems controlling your drinking, being preoccupied with alcohol, continuing to use alcohol even when it causes problems, having to drink more to get the same effect, or having withdrawal symptoms when you rapidly decrease or stop Read more…