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Alzheimer’s disease is the most common cause of dementia. This topic focuses on other conditions that cause dementia. For more information on Alzheimer’s, see the topic Alzheimer's Disease.

What is dementia?

We all forget things as we get older. Many older people have a slight loss of memory that does not affect their daily lives. But memory loss that gets worse may mean that you have dementia.

Dementia is a loss of mental skills that affects your daily life. It can cause problems with your memory and how well you can think and plan. Usually dementia gets worse over time. How long this takes is different for each person. Some people stay the same for years. Others lose skills quickly.

Your chances of having dementia rise as you get older. But this does not mean that everyone will get it. Many older adults never get it. By age 85, about 35 out of 100 people have it.¹ That means that 65 out of 100 people this age do not have dementia. And after age 85, even more people will get dementia.

If you or a loved one has memory loss that is getting worse, see your doctor. It may be nothing to worry about. If it is dementia, treatment may help.

What causes dementia?

Dementia is caused by damage to or changes in the brain. Things that can cause dementia include:

• Strokes, tumors, or head injuries. After Alzheimer's disease, strokes are the most common cause of dementia. This type of dementia is called vascular dementia.
• Diseases, such as Parkinson's disease, dementia with Lewy bodies, and frontotemporal dementia.

In a few cases, dementia is caused by a problem that can be treated. Examples include having an underactive thyroid gland (hypothyroidism), not getting enough vitamin B12, and fluid buildup in the brain (normal-pressure hydrocephalus). In these cases, treating the problem may cure the dementia.

In some people, depression can cause memory loss that seems like dementia. Depression can be treated.

As you age, medicines may affect you more. Taking some medicines together may cause symptoms that look like dementia. Be sure your doctor knows about all of the medicines you take. This means all prescription medicines and all over-the-counter medicines, herbs, vitamins, and supplements.

What are the symptoms?

Usually the first symptom is memory loss. Often the person who has a memory problem does not notice it, but family and friends do. As dementia gets worse:

• You may have more trouble doing things that take planning, like making a list and going shopping.
• You may have trouble using or understanding words.
• You may get lost in places you know well.

Over time, people with dementia may begin to act very different. They may become scared and strike out at others, or they may become clingy and childlike. They may stop brushing their teeth or bathing.