Although we still don’t know how Alzheimer’s disease begins, it is observed that damage to the brain starts a decade or more before the symptoms become evident. During the early onset of Alzheimer’s, the person is free of symptoms, but toxic changes are happening in the brain. Over time, neurons lose the ability to transmit messages, and eventually they are destroyed.
Before long, the damage spreads to the hippocampus, a structure in the brain which is essential in forming memories. As more neurons are damaged, the affected areas in the brain begin to shrink. By the final stage of Alzheimer’s, many other areas of the brain are damaged, and the person has a complete memory loss and is totally dependent on the caregiver.
Alzheimer’s is a slow disease that progresses in three stages—an early stage with no symptoms, a middle stage with mild cognitive impairment, and a final stage where there is complete memory loss. The time from diagnosis to death varies—as less as three or four years if the person is 80 years or older when diagnosed, to as long as ten years or more if the person is younger.
Dementia is a syndrome that impairs cognitive functioning—thinking, remembering, and reasoning—and behavior, and thereby affects a person’s daily life and activities. Dementia can be mild when it is just starts to affect a person's daily functioning, and turns severe where the person becomes totally dependent on others for basic activities in daily living.
Many conditions and diseases can cause dementia. The most common cause of dementia in older people is Alzheimer’s disease. Vascular dementia is caused due to a series of strokes or changes in the brain’s blood supply.
Other conditions that may cause dementia include:
Problems such as stress, anxiety, or depression can make a person more forgetful and symptoms of these conditions can be mistaken for dementia. For example, a person who has recently retired or someone coping with the death of a spouse may feel sad, lonely, worried, or bored. Trying to deal with these life changes may make some people to be confused or forgetful. Support from family and friends can help reduce such problems to a great extent.
Everyone forgets now and then. You should be concerned only when there is a memory loss that progresses gradually, and when it starts to disrupt your daily functioning.
Although it is observed that approximately 50 percent of the people affected with Alzheimer's are usually 75 years and above, in some cases, people in their 40s or 50s can also be affected with Alzheimer's.