Alzheimer’s disease isn’t the only cause of dementia. Unfortunately, there is no way to know for sure what type of dementia a person has. There is no blood test or x-ray that can diagnose Alzheimer’s or other types of dementia. The only sure way to know if someone had Alzheimer’s disease, unfortunately, is to examine their brain after they die.

The symptoms are a little different in each type of dementia. It’s good to know the difference to help you understand why someone is acting the way they are.

Frontal-Temporal Dementia

Look at the picture of the brain below. Put your hand on your forehead. The part of your brain just behind your forehead is called the frontal lobe. Now slide your fingers from the front to the side of your head (your temple). This part of the brain is called the temporal lobe.

There is a type of dementia that affects this part of the brain. It is called frontal-temporal dementia. It is the most common type of dementia in people under the age of 60. It’s not nearly as common as Alzheimer’s and it starts at a much younger age.

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We use this part of our brain to make decisions, to tell right from wrong, and to control our emotions. We use this part of the brain to plan for the future. People with dementia in this part of the brain have poor judgment and lose the ability to tell right from wrong. They also have less control over their behavior.

So instead of losing short-term memory like people with Alzheimer’s disease, a person with frontal-temporal dementia might start doing some things that are confusing to their friends and family. They might steal, even though they have never stolen in the past. They might make inappropriate sexual remarks or engage in inappropriate sexual behaviors, even though they’ve never done these things in the past.

Vascular Dementia

Vascular dementia is caused by lots of small strokes. This can happen when people don’t control their high blood pressure. Generally, vascular dementia doesn’t affect memory as much as Alzheimer’s. This is because the damage is spread throughout the brain.

Vascular dementia causes mood changes that are stronger than the mood changes you might see in someone with Alzheimer’s. It can also affect judgment—but not as strongly as in someone with frontal-temporal dementia.

You might have cared for more than one patient with vascular dementia because many older adults have high blood pressure that isn’t under good control. You may also see vascular dementia in someone who has had a stroke.

Lewy Body Dementia

Lewy body dementia is less common than Alzheimer’s dementia, frontal-temporal dementia, or vascular dementia. It is responsible for a little less than 5% of all cases of dementia. People with Parkinson’s disease can have this type of dementia.

Lewy body dementia happens when tiny unwanted molecules form in the brain. These unwanted molecules (Lewy bodies) become scattered throughout the brain.

People with Lewy body dementia usually don’t have problems with memory, at least at first. But they can have hallucinations, mental changes, and sudden confusion. These symptoms can come and go throughout the day.

Lewy body dementia can also affect a person’s sleep and cause a person to suddenly faint or pass out. This means a person with Lewy Body dementia is at high risk for unexpected falls.