What is Alzheimer's disease?

Please note: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your doctor about any questions you may have regarding a medical condition.

Alzheimer's disease is a brain disease that slowly destroys memory and thinking skills. It is a progressive disease, which means it gets worse over time. Alzheimer's is the most common cause of dementia among people aged 65 and older. Rarely, people younger than 65 can have Alzheimer's. About 5.8 million people in the United States have Alzheimer's disease. You're more likely to get Alzheimer's if one or more of your close family members – parents, brothers, or sisters – has it. The most common early symptom of Alzheimer's disease is trouble remembering recent events. Other early symptoms may include: Having trouble completing daily tasks, and Getting lost when driving on a route the person used to know well. These symptoms are not the same as normal forgetfulness, which can happen to all of us as we get older. For example, if you sometimes forget about an appointment, forget a person's name, or misplace your keys, it doesn't mean you have Alzheimer's. Doctors don't fully understand what causes Alzheimer's disease in most people. Most people with Alzheimer's disease are older, but just getting older doesn't cause the disease. Many people live well into their 90s without getting Alzheimer's disease. Doctors now know that changes begin happening in the brain 10-20 years or more before a person with Alzheimer's disease shows any symptoms. Neurons are brain cells that send and receive signals to and from the brain. Everything we do as living beings – walking, thinking, forming memories – happens because of these signals. A healthy adult brain contains about 100 billion neurons. When a person has Alzheimer's disease, tiny pieces of a protein called beta amyloid build up in between neurons, forming clusters, or plaques. Another protein, called tau, builds up inside neurons, forming dense, thread-like tangles. Together, these plaques and tangles block neurons from sending and receiving signals. Because of these and other abnormal changes in the brain, neurons start to die. The first place this happens is in the parts of the brain where memories are formed. As more neurons die, the brain starts to shrink. As Alzheimer's gets worse over time, the brain may shrink to about a third of its normal size. When Alzheimer's disease becomes severe, a person loses much of their ability to communicate and needs full-time help to take care of themselves.