Welcome to Alzheimer Wiki, a comprehensive online guide to understanding Alzheimer’s disease.

Alzheimer’s disease is the most common cause of dementia, accounting for about fifty to seventy percent of all cases of dementia. An estimated four million Americans exhibit Alzheimer’s symptoms. Alzheimer’s disease is usually diagnosed after age sixty; the average age of Alzheimer’s sufferers is eighty.

Memory Loss and Other Dementia Symptoms

Alzheimer’s disease, like other forms of dementia, is characterized by memory loss and a progressive deterioration of mental functions. Memory loss caused by Alzheimer’s may be mistaken for the natural memory loss that comes with age. As the disease progresses, however, memory loss worsens, language abilities decline, and it becomes increasingly difficult to plan or think abstractly. Eventually, memory loss and mental functioning become so impaired that full-time care is required. Learn more about Alzheimer’s symptoms.

Amyloid Plaques, Brain Lesions, and Alzheimer’s Disease

The cause of Alzheimer’s disease is unknown, but the disease has been linked to certain types of brain lesions. These brain lesions were discovered in 1906 by a German doctor named Alois Alzheimer. Dr. Alzheimer noticed the distinct brain lesions during an autopsy of a woman who had died with dementia. Even today, the only way to definitively diagnosis Alzheimer’s disease is to examine the brain for these brain lesions after death.

The two types of brain lesions are referred to as amyloid plaques and neurofibrillary tangles. Amyloid plaques are composed of amyloid proteins. The amyloid proteins slowly build up in the brain. Like amyloid plaques, neurofibrillary tangles are accumulations of proteins in the brain. Instead of amyloid, however, the “tangles” are composed of a protein named “tau”.

Acetylcholine Levels

In addition to amyloid plaque brain lesions, another characteristic of Alzheimer’s disease is low levels of the neurotransmitter acetylcholine. Acetylcholine plays an important role in memory recall and cognitive function.

Alzheimer’s Disease and an Aging Population

As life expectancies increase, the population in the United States, and many other countries, is aging. With greater life expectancy comes a higher rate of Alzheimer’s disease. By 2050 the number of Americans with Alzheimer’s may increase from the current four million to over thirteen million.

For more information on Alzheimer’s disease, browse our Alzheimer Wiki pages.