Behavioral Variant FTD (bvFTD)
Behavioral variant FTD (bvFTD) is the form of frontotemporal degeneration (FTD) characterized by early and progressive changes in personality, emotional blunting and/or loss of empathy. Patients experience difficulty in modulating behavior, and this often results in socially inappropriate responses or activities. Impairment of language may also occur after behavioral changes have become notable.
Patients typically start to have symptoms sometime in their 50s, though it can occur as early as at age 20 or as late as age 80. As with all FTD, the course of bvFTD will vary from one person to another. Not every symptom will be experienced by every person, nor will these symptoms develop in a pre-ordained sequence.
Key Clinical Features
The hallmark of behavioral variant FTD is a progressive deterioration in a person’s ability to control or adjust his or her behavior in different social contexts that results in the embarrassing, inappropriate social situations that can be one of the most disturbing facets of FTD. People manifest a loss of empathy early in the disorder that is often seen as indifference toward others, including loved ones. Apathy or lack of motivation may also be present. The patient typically does not recognize the changes in his or her own behaviors, nor do they exhibit awareness or concern for the effect these behaviors have on the people around them.
- Hyperoral behaviors include overeating, dietary compulsions, in which the person restricts himself to eating only specific foods (such as a certain flavor of Lifesaver, or eating food only from one fast food restaurant) or attempts to consume inedible objects. Patients may consume excessive amounts of liquids, alcohol and cigarettes.
- Stereotyped and/or repetitive behaviors can include re-reading the same book multiple times, hand rubbing and clapping, humming one tune repeatedly or walking to the same location day after day.
- Personal hygiene habits deteriorate early in the disease progression, as the person fails to perform everyday tasks of bathing, grooming and appropriate dressing.
- Hyperactive behavior is exhibited by some patients, and can include agitation, pacing, wandering, outbursts of frustration and aggression.
- Hypersexual behavior can range from a preoccupation with sexual jokes to compulsive masturbation.
- Impulsive acts can include shoplifting, impulsive buying and grabbing food off another person’s plate.
- Apathy or indifference toward events and the surrounding environment can be marked by reduced initiative, and lack of motivation.
- Lack of insight into the person’s own behavior develops early. The patient typically does not recognize the changes in his or her own behaviors, nor do they exhibit awareness or concern for the effect these behaviors have on the people around them, including loved ones.
- Emotional blunting develops early in the course of the disorder, and is manifested as a loss of emotional warmth, empathy and sympathy, and development of what appears to be indifference toward other people, including loved ones.
- Mood changes can be abrupt and frequent.
- Symptoms similar to those seen in Parkinson disease. Among bvFTD patients, the term “parkinsonism” is used to distinguish the fact that they do not have Parkinson disease, though they do exhibit some of these symptoms. Symptoms include: decreased facial expression, bradykinesia (slowness of movements), rigidity (resistance to imposed movement) and postural instability.
Key Pathological Features
Patients with behavioral variant FTD may have one of three abnormal protein collections in their brain cells, which can be seen at autopsy: TDP-43, tau, or fused in sarcoma (FUS) protein. See Overview of FTD for details. The bulk of these protein buildups is usually found in the brain areas that have lost the most volume, the frontal and temporal lobes.
The majority of bvFTD cases have not been linked to genetic mutations.
As with all forms of FTD, there is currently no cure for bvFTD, and in most cases its progression cannot be slowed. Although no medications have been proven effective specifically in FTD, many clinicians look to the medications and treatment approaches targeting behavioral disturbances as necessary.
For instance, some FTD patients benefit from selective serotonin reuptake inhibitors (SSRIs, used in treating obsessive-compulsive behaviors, such as hoarding or craving sweets). Clinicians may also recommend antioxidants, such as coenzyme Q10, which are known to slow the progression of damage to brain cells in general, but there is little evidence to support this in frontotemporal degeneration.