The nerve cell damage caused by frontotemporal dementia leads to loss of function in these brain regions, which variably cause deterioration in behavior, personality and/or difficulty with producing or comprehending language. There are a number of different diseases that cause frontotemporal degenerations. The two most prominent are 1) a group of brain disorders involving the protein tau and 2) a group of brain disorders involving the protein called TDP43. For reasons that are not yet known, these two groups have a preference for the frontal and temporal lobes that cause dementia. Frontotemporal dementia used to be called Pick’s disease after Arnold Pick, M.D., a physician who in 1892 first described a patient with distinct symptoms affecting language. Some doctors still use the term “Pick’s disease.” Other terms you may see used to describe frontotemporal dementia include frontotemporal disorders, frontotemporal degenerations and frontal lobe disorders.
Types ; Behavior variant frontotemporal dementia (bv FTD) is characterized by prominent changes in personality and behavior that often occur in people in their 50s and 60s, but can develop as early as their 20s or as late as their 80s. In behavior variant frontotemporal dementia, the nerve cell loss is most prominent in areas that control conduct, judgment, empathy and foresight, among other abilities. Primary progressive aphasia (PPA) is the second major form of frontotemporal degeneration that affects language skills, speaking, writing and comprehension. PPA normally comes on in midlife, before age 65, but can occur in late life also. The two most distinctive forms of PPA have somewhat different symptoms:
- In semantic variant of PPA, individuals lose the ability to understand or formulate words in a spoken sentence.
- In nonfluent/agrammatic variant of PPA, a person’s speaking is very hesitant, labored or ungrammatical.
Disturbances of motor (movement or muscle) function include three disorders that are a part of the frontotemporal degeneration spectrum that produce changes in muscle or motor functions with or without behavior (bvFTD) or language (PPA) problems:
- Amyotrophic lateral sclerosis (ALS), which causes muscle weakness or wasting. ALS is a motor neuron disease also known as Lou Gehrig’s disease.
- Corticobasal syndrome, which causes arms and legs to become uncoordinated or stiff.
- Progressive supranuclear palsy (PSP), which causes muscle stiffness, difficulty walking and changes in posture. It also affects eye movements.