Most people think that everyone with dementia has Alzheimer's disease. That's not true. There are many types of dementia. Knowing what kind of dementia a person has is important because care may be different for different types. And, knowing what kind of dementia lets you know what will happen to the person over time.
Alzheimer's Disease: 60% - 80% of dementia cases
Alzheimer's is the most common type of dementia. It is caused by damage to nerve cells in the brain, but we don't know why that damage happens. In the early stage of Alzheimer's a person will have difficulty recalling recent events and people's names. They may care less about things or feel depressed. Later, memory problems become worse. They may begin to show poor judgment, or become confused or fearful. With advanced Alzheimer's a person may have trouble speaking, swallowing, and walking.
Vascular Dementia: 10% - 20% of dementia cases
Vascular means "blood vessels." Vascular dementia happens when cholesterol clogs up the blood vessels to the brain. This causes small strokes. Vascular dementia happens most often to people who have high blood pressure, diabetes, and high cholesterol. It also happens to some people when their heart goes out of rhythm due to a problem called "a-fib."
Vascular dementia often begins suddenly and gets worse and worse with each small stroke. Everyone with vascular dementia will have different symptoms. That's because each little stroke can affect a different part of the brain. Some people might have memory problems. Others might have problems with judgment and planning. Still others may have loss of bladder or bowel control, a stiff face, or weakness on one side of the body.
Many people have mixed dementia. Mixed dementia happens when someone has both Alzheimer's and vascular dementia. Research shows that almost half of people with Alzheimer's have some vascular dementia. Most people over age 80 who have dementia have mixed dementia.
Lewy Body Dementia: 10% of dementia cases
Lewy body dementia is caused by clumps of protein in the front part of the brain. These clumps are called "Lewy bodies." They are named after a Dr. Lewy.
People with Lewy body dementia have memory loss and thinking problems, just like in Alzheimer's disease. But, they are more likely to also have sleep problems, see things that aren't there, and their thinking ability will have both good days and bad days. Lewy body dementia is common in people with Parkinson's disease - a condition where people have problems like total body stiffness and shaking (tremor) of the arms and hands.
Fronto-Temporal Dementia: 5% of dementia cases
Most people have never heard of fronto-temporal dementia. But, it is the cause of 1 out of every 20 cases of dementia. It is called fronto-temporal because it happens when there is damage to nerve cells in the front and side (temple) of the brain. We don't know why fronto-temporal dementia occurs.
Fronto-temporal dementia affects people in their 40s and 50s, which is younger than in Alzheimer's disease. Damage to the front and side of the brain causes changes in a person's personality, behavior, and language. Examples of mild problem behaviors are constant humming or whistling, banging on a table, and eating too much. More serious behaviors are things like jumping out of cars or acting out sexually. These behaviors are difficult to control.
While people with Alzheimer's dementia live for an average of 8 years, people with fronto-temporal dementia don't live that long.
Other Types of Dementia
There are also many other kinds of dementia. A special kind of dementia can occur in people with HIV. Another kind occurs in people who have brain damage from drinking too much alcohol. And, there are others types, too. The many kinds of dementia are part of why it is so important to have a medical exam when an older adult has problems with memory or behavior.
The exam can help figure out what is causing the problems and what are the next steps.
Written by: Jane Mohler, FNP, MPH, PhD, Arizona Center on Aging