Dear Doctor: Can you talk about FTD dementia, especially the type that affects behavior? I am sure that a close acquaintance has it, although she is clear-minded. Her symptoms involve increasingly strange behavior and, lately, social withdrawal.
Dear Reader: You’re referring to a group of brain disorders known as frontotemporal dementia, or FTD. Originally identified about a century ago, the condition is caused by damage to the nerves, also known as neurons, in the frontal and temporal lobes of the brain. For reasons that are not yet understood, people with FTD experience a buildup of certain proteins within these two areas of the brain. This leads to the progressive loss of structure, and even death, of the neurons, which causes these lobes of the brain to shrink.
Unlike Alzheimer’s disease, which typically begins with cognitive problems and memory loss, the onset of FTD is marked by changes to the individual’s personality, social behavior or language abilities. This is due to the specific functions performed by the areas of the brain affected by FTD. The frontal lobe, one of the four lobes of the human brain, is involved in mood, personality, emotional expression, self-awareness, language and judgment. The temporal lobe, which processes sound, also plays a key role in understanding and using language, and in the management of sensory input, including pain, visual stimuli and emotion.
Depending on the specific site of the nerve damage, symptoms of FTD can show up as either problems with language or changes to behavior and personality. The type of FTD that you’re asking about, known as behavioral variant FTD, affects about half of all people with the condition. In this type of FTD, an individual’s personality begins to gradually change. They lose inhibitions, which leads to inappropriate social behavior. They can become impulsive and tactless; lose the ability to feel sympathy or empathy; can’t think logically or solve problems; and are unable to plan ahead. They also lose self-awareness, so they’re unable to recognize the changes that are taking place.
The second major type of FTD features disturbances to the ability to speak, read and understand language. It can also include behavioral changes. Some people diagnosed with FTD also experience changes to reflexes, muscular weakness and a slowing of their movements.
FTD is the most common type of dementia in people under the age of 60. About two-thirds of cases of FTD occur between ages 45 and 65. Diagnosis includes a detailed medical history; tests to assess behavior, memory, language and neurological function; and brain scans to look for atrophy. The cause of this type of dementia is unknown, but researchers have connected it to certain genetic mutations. It’s not inherited, but FTD does run in families. Up to 40% of diagnosed patients have a family history of the condition.
Unfortunately, there is no cure at this time. Although your friend’s behavior does match certain symptoms of FTD, other potential causes can include physical illness, substance abuse and mental illness. If you’re interested in additional information and support relating to FTD, visit theaftd.org.
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