What is frontotemporal dementia?

Common symptoms include language problems and abnormal behavior in middle age.

Many people know the form of dementia called Alzheimer’s disease. But what is frontotemporal dementia (FTD)? Damage to nerves in certain parts of the brain causes a group of frontotemporal disorders, affecting behavior and language as I’ll describe below.

Early signs of frontotemporal dementia

Have you noticed someone behaving differently? Is your coworker doing odd things, such as slapping each door as they walk down the hall? Or has your previously kind and caring spouse lost their capacity for empathy, such that when you told them about your cancer diagnosis, they complained that your treatment schedule would interfere with their golf game? If so, they might be showing early signs of the behavioral variant of FTD.

Maybe there’s a problem with language, rather than behavior. Perhaps it started with difficulty finding words (like any older adult), but is your sibling now having trouble with grammar and getting out an intelligible sentence? Or does your friend not know the meaning of some ordinary words, like pizza, lemonade, wood, or metal? If so, they might be showing signs of primary progressive aphasia, which may also be due to FTD.

A common pathology inside the brain

What’s the connection between these behavior and language problems? Why are they both part of FTD?

Both have the same underlying causes: a family of abnormal proteins that can be seen under the microscope. In fact, more than a dozen different pathologies can cause FTD. Each of them can lead to either behavioral variant frontotemporal dementia or the language difficulties of primary progressive aphasia.

Location, location, location

How can the same pathology — the same abnormal protein — lead to either behavior problems or language problems, or sometimes both? The answer is, it depends on where the pathology is.

The frontal lobes of your brain, behind your forehead, regulate and guide your personality, judgement, and behavior. So, if the frontotemporal pathology is in this region, it will cause changes in personality, judgement, and behavior.