Some Basic Questions about Adults with Intellectual/Developmental Disabilities Affected by Alzheimer's Disease or Other Dementia

Q. What is Alzheimer's disease?
Alzheimer is a progressive, neurodegenerative disease, characterized by loss of function and death of nerve cells in several areas of the brain leading to loss of cognitive function such as memory and language. The cause of nerve cell death is unknown. Alzheimer's disease is the most common cause of dementia.

Q. What is dementia?
Dementia is a term used to describe cognitive decline from any cause (e.g., head injury, stroke, anoxia) that occurs at any stage of life beyond childhood and after the person is generally functional. The term applies to cognitive decline that results in impaired personal, social, or occupational adaptation, is persistent and progressive, and is associated with a chronic diffuse or multifocal brain disorder. This decline is generally attributed to a neuropathological process (that is, a disease or damage of the brain itself).

Q. Does Alzheimer's disease affect people with intellectual disabilities the same as it does other people?
Yes, like other affected persons, people with intellectual disabilities who have Alzheimer's disease suffer memory loss, disorganization and loss of skills, and changes in personality and behavior. However, in people with Down syndrome, these changes are often seen much earlier in the lifespan.

Q. What is the prevalence of Alzheimer's disease in adults with intellectual disabilities?
Studies have found the prevalence of dementia in persons with intellectual disabilities to be about the same as in the general population. Dementia appears in about 3% of the adult population over the age of 40 years, 6% of the population over the age of 60 years, and 12% of the population over the age of 80 years. Adults with Down syndrome show a much higher rate: about 20% among adults age 40 and older and 56% among adults age 60 and older.

Q. When does Alzheimer's disease generally appear in persons with intellectual disabilities?
Onset is generally observed to occur in the mid-60s for adults with intellectual disabilities (other than Down syndrome) and in early 50s for adults with Down syndrome.

For more information, please contact:
Matthew P. Janicki, Ph.D.Associate Director for Technical Assistance
Rehabilitation Research and Training Center on Aging with Developmental Disabilities

University of Illinois at Chicago
1640 Roosevelt Road
Chicago, IL 60608-6904