Strange Behavior Caused by Frontotemporal Dementia (FTD)

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Home / Strange Behavior Caused by Frontotemporal Dementia (FTD)

In FTD, the front part of the brain (arrow) is atrophied. Copyright image by James Cooper, all rights reserved.

“I like your wig, it’s really nice,” he said, with sincerity, to the woman in the hallway he had never seen before. She abruptly turned and walked away.

“I bet you’re great in bed, honey,” he said to the attractive young female physician, nodding his head in self-agreement. She ignored his comment, and continued taking a medical history.

We were evaluating this 61 year-old retired dentist in our clinic. “He says things he never would have before. I guess his personality just changed. And you should see how he goes for sweets now!” his wife said.

With that, she essentially made the diagnosis for us, pointing directly towards frontotemporal lobe degeneration (FTD).

What is FTD? (Frontotemporal Lobe Dementia)

FTD is a common but under-diagnosed type of dementia. It’s a dementia because it is a progressive brain disorder that results in death of brain cells, and, ultimately, memory loss. Family support groups often prefer that the “D” stand for degeneration.

This emphasizes FTD as a unique disorder, separate from the most common dementia, Alzheimer’s. Also, “dementia” may bring to mind a completely different and incorrect picture of how the person with FTD functions early in the disease.

FTD is a fairly big umbrella under which a number of interesting clinical syndromes exist. Each clinical syndrome has a separate diagnosis name. Most have in common that they are “tauopathies,” meaning that at the level of the brain cell, the neuron,  abnormal tau can be found.

Tau (rhymes with cow) is a microtubule associated protein. Microtubules are like old-time coal shafts that allowed coal lumps to go from the street to the furnace in the basement. Microtubules are access channels that allow large molecule proteins to enter the neuron. Tau holds the shaft open. When tau is abnormal, the shaft collapses and the neuron starves.

Abnormal tau and neuron fragments (tangles) can be identified microscopically in tauopathies. No one knows what causes the abnormal tau, but it is often associated with gene mutation.

The specific disease or clinical picture that erupts from tauopathy depends on two factors: variation in the tau abnormality, and, mostly, the location in the brain where the abnormality and brain circuit disruption occurs.  In FTDs, the brain circuit disruptions occur in the frontal lobe or temporal lobes (which are the sides of the frontal lobe).

The case described here, the dentist with the fresh mouth (uninhibited speech), and sweet craving, is an example of the behavioral variant of FTD, bvFTD, the most common FTD. Besides uninhibited behavior, signs and symptoms associated with bvFTD often include apathy and utilization behavior (doing something that is a normal function, but not for any apparent reason, e.g., opening and closing a drawer, or shuffling through a stack of papers). Some have suggested that most extreme hoarders have some frontal lobe abnormality.

Temporal Lobe Loss: Related Behaviors

Drs. Kluver and Bucy removed a large part of the temporal lobes of monkeys, disrupting massive numbers of temporal (frontal) lobe circuits.  The monkeys were found to masturbate (more than their usual amount); to be apparently more fearless, ignoring snakes;  to fail to recognize familiar objects, and to be hyper-oral, stuffing objects into their mouths with great abandon. Kluver-Bucy syndrome can occur in humans as a result of FTD. Also, herpes infection, Alzheimer’s, and trauma can cause Kluver-Bucy syndrome.

The Red Baron’s Brain Injury

The Red Baron was a flying ace in WW I. His flying skill and judgment were excellent, until his judgment let him down. The Baron received a brain injury in combat. He became sullen, withdrawn, and made poor judgments. Once he even flew low over enemy lines pursuing a damaged enemy plane, an action he warned his students never to do.

He was trying to make another score, a score he did not need. His low flight made him vulnerable to ground machine guns. He was hit and killed. It is believed that his earlier brain trauma led to a change in his personality, from an accurate but cautious flyer to an immature poor decision-maker, a person with FTD from brain trauma.

Clearly, damage to the frontal lobe can cause distressing, even heartbreaking changes in behavior. The monkeys who lost part of their frontal brain, the people with Kluver-Bucy syndrome, the Red Baron, extreme hoarders, and those with bvFTD are examples. Since behaviors define personality, frontal lobe damage can change a person’s personality.

Treating FTD

The US Food and Drug Administration (FDA) has approved no medications for treatment of FTD. Research has shown that Donepezil (Aricept), rivastigmine (Exelon) and similar medications are not useful. While early studies were encouraging, definitive studies of memantine (Namenda) have shown it appears to have no value for treating FTD.

However, there are treatments that are generally accepted as useful. These are behavioral interventions. If the family understands the patient cannot help his lack of inhibition, they can be supportive rather than critical.

Sometimes public explanations of the behavior will sooth an offended person. Some families have cards printed, “My wife has a condition in which she may say inappropriate things. We apologize if you are offended, and hope you will understand.” Knowledge about this condition by the family can reduce embarrassment, safeguard finances, and protect the person’s quality of life.

Note: Cases described in this article are based on real cases and are meant to be typical. However, details have been scrambled, so each case should be considered fictional;  any similarity to any patient is purely coincidental.

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