By Stacey Burling, Inquirer Staff Writer

For several years, Sylvia Gentry noticed that her husband, Louis, was behaving oddly, but she didn't suspect he might have a brain disease.

Their saga began about 10 years ago. He left the table midway through dinner with guests he'd liked for 30 years - they were boring, he told her. One Thanksgiving, he threw an artificial log in the fireplace, still wrapped in plastic.

Oddest of all, he began to cross social boundaries. He'd ask embarrassing questions and hug strangers. He became overly flirtatious with young women. If the couple went out to eat, he'd spend all his time talking to the waitress.

Sylvia Gentry, a social worker, was just annoyed at first. Louis Gentry, a financial asset manager, had always been a social man. But, as his miscues multiplied and he couldn't control them, she grew more worried.

She took him to a neurologist. Her husband had a form of dementia she'd never heard of: frontotemporal degeneration (FTD).

It tends to start young - the average age of onset is 59 - and it affects behavior or language. Unlike in the best-known of the dementias, Alzheimer's disease, memory problems are not an early symptom. FTD affects an estimated 50,000 to 60,000 Americans; like Alzheimer's, it is fatal and incurable.

The Gentrys' story is a common one. It often takes years to get a diagnosis. Symptoms are mistaken for a stress reaction or a psychiatric problem. Murray Grossman, a neurologist who heads the Penn FTD Center, said the symptoms are hard to detect and, often, "we don't want to detect them."

Gentry and Grossman spoke recently at the ninth annual FTD Caregiver Conference sponsored by Grossman's center. The day-long event drew 200 people from 11 states to the Penn campus.

During open forums, the crowd asked about medical marijuana and how to get a patient to stop driving. One young woman asked about aggressive behavior. Her father had used racial epithets and called someone fat in a restaurant. The FTD association handed out cards - available on the group's website - that family members can give to bystanders. "Please pardon my companion's language/behavior," they said. "He/She has a brain disease called frontotemporal degeneration, which makes it difficult to control comments and actions."

FTD encompasses a group of diseases characterized by progressive loss of cells in the frontal and temporal regions of the brain. Like Alzheimer's disease, FTD is thought to be caused by accumulation of misfolded proteins. In Alzheimer's, those errant proteins are amyloid and tau. In FTD, the culprits are tau or TDP-43.

Scientists have only recently learned that the misfolded proteins can cause both physical and cognitive problems. ALS or Lou Gehrig's disease and FTD are now considered to be on the same spectrum because both can be caused by TDP-43.

"This has really been a game-changer for us," said Penn neurologist Lauren Elman. "In the future, ALS and FTD will be treated with the same medications."

John Trojanowski, codirector of Penn's Center for Neurodegenerative Disease Research, said 80 percent of patients with another disabling disease, Parkinson's, eventually develop a non-FTD dementia. They can have protein clumps called Lewy bodies or Alzheimer's pathology.

Biomarkers for tau are in testing. And Grossman hopes to have an effective treatment in 10 years.

On average, FTD patients die in about seven years.

Gentry, who coleads a support group for FTD caregivers in Wynnewood, said she was "totally overwhelmed with grief and fear" when her husband was diagnosed.

It helped her, she said, to stop covering for Louis, now 83, and start telling people what was wrong with him. Their social lives narrowed as he found it harder to sit still for a play or concert. Any movie had to have few characters, no flashbacks, no subtitles, and a single story line. He's happy to watch war stories on TV. He can't do chitchat. He drives her crazy in the car, talking incessantly and changing the temperature from full heat to full cold. "There are a lot of situations I can't put myself in anymore," she said.

Gentry, 72, said she had gotten support from friends, family, neighbors, and, of course, the support group. "We can't choose what comes into our lives," she told the crowd, "but we can choose what we do with it."

215-854-4944 @StaceyABurling