Frontotemporal dementia (FTD) is the second most common dementing illness in those under the age of 65. In general, it affects a younger population than Alzheimer’s disease. Unlike Alzheimer’s disease, FTD is more likely to start in the 50s-70s than in the 80s.
FTD is an umbrella term, and your neurologist may give a more specific diagnosis based on each patient’s history and symptoms. According to the most severe or the earliest symptoms, neurologists can sometimes give a more specific FTD diagnosis. These possibilities include:
- Behavioral variant FTD – these patients have prominent, early changes in their behavior (such as being more impulsive or irritable), social interaction with others (kissing strangers, crude or explicit remarks), initiative to participate in hobbies (too much or too little), ability to control one’s own actions (excessive eating, pacing), or decision making abilities. In the past, behavorial-FTD may have been called Pick’s disease or FTD. Nowadays, the term Pick’s disease is reserved for a very specific type of change in the brain only detectable under a microscope, and FTD is used more broadly to include behavorial-FTD and other types of FTD.
- Primary Progressive Aphasia (PPA) – these patients have language abnormalities early in the disease course, although they can develop personality and behavior changes later. Depending on the type of language and speech problems in each patient, neurologists can further classify PPA into semantic variant PPA or semantic dementia, agrammatic/non-fluent PPA or progressive non-fluent aphasia, and logopenic progressive aphasia.
- Corticobasal syndrome (CBS) – these patients have troubles with planning and execution of certain actions, and may have a hard time using familiar objects, both simple (a fork) and complex (a computer keyboard). Some of these patients may walk or move like they have Parkinson’s disease, and some develop speech changes similar to PPA. Other symptoms may emerge later in the disease course.
Some behavorial-FTD and PPA patients develop troubles with walking and moving their eyes, and this combination of symptoms may suggest another related condition called progressive supranuclear palsy (PSP).
About 10-15% of the patients can develop symptoms of amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease).
Wwhen someone is diagnosed with Alzheimer’s disease, there is a 85-90% chance that changes seen in his or her brain are similar to the changes seen in other brains of patients diagnosed with Alzheimer’s disease. A number of unique neuropathologic changes have been identified in FTD, and many scientists at Emory and elsewhere are working on how to tell these changes apart by clinical examination, MRI, testing of blood or spinal fluid, or a combination of these tests.
10-15% of patients have changes similar to patients with Alzheimer’s disease, even though their symptoms do not resemble the forgetfulness seen in those with Alzheimer’s disease. A spinal fluid test for Alzheimer’s disease may identify those in this group.
Some patients show changes in a protein called TDP-43. These cases are referred to as “FTLD-TDP”.
Some patients have changes associated with an abnormal form of the protein Tau. Neurologists and pathologists refer to these cases collectively as “FTLD-Tau” or “tauopathy”, although they may refine their diagnosis with more specific terms such as Pick’s disease, corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), etc.
A small group of patients have changes in a protein called FUS, and this group is known to have FTLD-FUS.
A collection of other related diseases account for the remaining cases of FTD.