What are the symptoms?
The symptoms of FTD depend on the affected parts of the brain. Even among identical twins, no two brains are the same, so FTD affects everyone differently. Many of the symptoms are similar, but they often happen in different combinations, or they might be more or less severe.
The symptoms of bvFTD fall under six categories:
- Loss of inhibitions.
- Apathy.
- Loss of empathy.
- Compulsive behaviors.
- Changes in diet or mouth-centered behaviors.
- Loss of executive function.
Loss of inhibitions
Inhibition is when your brain tells you not to do something. Losing your inhibitions because of frontal lobe deterioration can look like any of the following:
- Loss of the “filter” for what you say. When this happens, you might say hurtful, rude or offensive things. For some people, this can seem like a major personality shift.
- Lack of respect for others. This often involves getting too close to people (ignoring their personal space) or touching them in unwelcome ways. Inappropriate sexual comments or actions are also common.
- Impulsive actions and behaviors. These are usually risky behaviors, such as reckless gambling or spending. Criminal behaviors like shoplifting are also possible.
Apathy
Healthcare providers commonly mistake apathy for depression because the two have many similarities. Apathy tends to look like the following:
- Loss of motivation.
- Social isolation.
- Decline in self-care and hygiene.
Loss of empathy
People who have a loss of empathy (sometimes known as “emotional blunting”) may have trouble reading the emotions of others. That may look like they’re behaving in a cold, unfeeling or uncaring way.
Compulsive behaviors
People with FTD often behave in noticeably different ways from people without this condition. Sometimes, behavior changes are small and happen in very limited ways. For others, the changes might be more complicated, involving multiple steps or a strict routine. Some examples include:
- Repetitive motions. People with FTD often repeat small-scale movements, such as clapping their hands, tapping their feet, pacing, etc.
- Complex or ritual-like behaviors. Compulsively watching the same movies, reading the same books or collecting types of items. Hoarding items also falls under this category.
- Speech repetition. A person with FTD may repeat the same sounds, words or phrases.
Changes in diet or mouth-centered behaviors
People with FTD often have a symptom known as "hyperorality," which means they overeat, eat things that aren’t food (this is a condition known as pica), or have mouth-centered compulsive behaviors (like smoking or using their mouth to feel things in a way similar to normal exploring behavior in babies).
Loss of executive function without losing other abilities
Executive function is your ability to plan and solve problems, stay organized and motivate yourself to carry out tasks. People with FTD have trouble with executive function, but other abilities like how you process what you see and your memory aren’t affected until later stages of the disease.
Primary progressive aphasia
There are three main subtypes of PPA, two of which can happen with FTD:
- Nonfluent variant (nfvPPA). This type involves problems with grammar and forming words. Individual words and simple sentences are understandable, but complicated sentences could cause confusion.
- Semantic variant primary progressive aphasia (svPPA). This type involves problems with choosing and understanding words. People with this often say things that don't make sense or can't understand what other people are saying.
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What causes frontotemporal dementia?
FTD happens when neurons, a key type of brain cell, deteriorate. This usually happens when there's a malfunction in how your body creates certain proteins. A key part of how proteins work is their shape. Much like how a key won't turn or open a lock if it's not the right shape, your cells can't use proteins when they're not the right shape. Your cells often can't break those faulty proteins down and get rid of them.
With nowhere to go, those misshapen proteins can tangle and clump together. Over time, these faulty proteins accumulate in and around your neurons, damaging those cells until they don’t work at all. Experts have linked misfolded proteins with FTD and its related conditions, such as Pick’s disease. Misfolded proteins also play a role in conditions like Alzheimer’s disease.
These protein malfunctions happen with certain DNA mutations. DNA is like an instruction manual for your cells, telling them how to do a specific job. Mutations are like typos in the manual. Your cells strictly follow DNA instructions, so even small mutations can cause problems.
Some DNA mutations run in families, which is why about 40% of FTD cases involve a family history of the disease. Mutations can also happen spontaneously, meaning you developed the mutation and didn't get it from your parents.
While they aren't causes, two other factors can increase the risk of developing FTD. One is having a history of head trauma, which more than triples your risk of developing FTD. Thyroid disease is also linked, making FTD 2.5 times more likely to develop.
Is it contagious?
FTD isn’t contagious, and you can't pass it from person to person. However, FTD does run in families, so your chance of developing it increases if you have a family member (especially a parent or sibling) who has FTD.
