For starters, dementia and Alzheimer's disease (AD) are not the same thing. Dementia is not a disease, but rather the name for a group of symptoms - such as the loss of abilities in thinking, remembering and reasoning - that interfere with everyday life.
Dementia can occur because of many things, and Alzheimer's disease is at the top of the list. Stroke is also common.
For most people with a memory disorder (more than 75 percent), one of these is probably the culprit:
- Alzheimer's disease: Complex brain changes that happen over many years cause late-onset AD. Genetic mutations usually cause early-onset Alzheimer's. Symptoms for late-onset and early-onset AD are the same, including memory that keeps going downhill, confusion, changes in behavior, lack of control over urination or defecation, and trouble with communicating.
- Vascular dementia: Caused by damage to blood vessels in the brain, usually from a stroke. Symptoms are similar to AD.
- Lewy body dementia (LBD): LBD occurs when abnormal deposits of protein damage the brain. It can cause balance problems, sleeplessness, hallucinations and Alzheimer's-like symptoms.
- Mixed dementia: With two or more causes, mixed dementia is often a combination of AD and vascular dementia.
Less common types of memory disorders include Parkinson's disease dementia, which occurs in 50 to 80 percent of people with the disease and has symptoms like AD; frontotemporal dementia, the result of ongoing loss of nerve cells in the brain's front and side regions; Creutzfeldt-Jakob disease, a rare disorder that quickly damages the brain; normal pressure hydrocephalus, an abnormal build-up of cerebrospinal fluid that puts pressure on the brain; and Wernicke-Korsakoff syndrome, which comes from not getting enough vitamin B, and is often associated with alcohol abuse.