THURSDAY, Sept. 15 (HealthDay News) -- A family confronted with Alzheimer's disease may well believe that it is the worst thing that can happen, but neurologists are describing a related brain condition that is even more troubling.
It's called frontotemporal dementia, named after the parts of the brain that it attacks -- the upper lobes of the front part of the organ. Alzheimer's, by comparison, affects the entire brain.
And while people with Alzheimer's disease suffer progressive loss of memory and ability to function, those with frontotemporal dementia may act wildly and bizarrely, veering into theft, sexual deviancy and other uncontrolled acts, according to experts.
"We know that many of these patients are said to be crazy and wind up in jail rather than in a hospital," said Dr. John Q. Trojanowski, director of the University of Pennsylvania Institute on Aging.
And the condition is a killer, according to a study in the current issue of the journal Neurology to which Trojanowski contributed. The study found that people who had frontotemporal dementia died much faster than those with Alzheimer's disease.
The 395 Alzheimer's disease patients died 8.7 years after diagnosis. The average survival time for the 177 people with frontotemporal dementia was three years. Some Alzheimer's patients lived as long as 11.8 years after diagnosis, while the longest survival time for those with the other condition was 5.7 years, the study found.
There are several possible explanations for the difference, said Dr. Erik D. Roberson, a research scientist at the University of California, San Francisco's Gladstone Institute of Neurological Disease, who took part in the transcontinental study and was lead author of the journal report.
One reason is that people with frontotemporal dementia are likely to get Lou Gehrig's disease, a fatal neurological disorder in its own right, Roberson said. Another is that "the patients' withdrawal and social barriers might lead them to be institutionalized early in the course of the disease, and there might be changes in quality of medical care they get," he said.
The most tantalizing possibility is that the tangles of tau protein found in the brains of patients with Alzheimer's disease might have a protective function, Roberson said. Frontotemporal dementia patients who survived longest were those who had tau-positive inclusions in their brains; those with no such inclusions died fastest, he said.
"Are these inclusions part of a problem or a brain's attempt to solve a problem?" Roberson said. "Some data in Huntington's disease indicate that tau-positive inclusions are a good thing that protect the brain."
Trojanowski has an even simpler explanation: It is simply the nature of frontotemporal dementia to be fast-moving, just as some forms of cancer are more malignant and kill more quickly, he said.
There is no immediate medical application for the finding, Roberson said. But if there are trials of a treatment in the future, patients would have to be tested more frequently than is done in trials of Alzheimer's disease, he said.
The possibility of such treatments and such trials exists, Trojanowski said, "because if we know what is broken, we can try to fix it."
But the most important message is for families of those people diagnosed with frontotemporal dementia, he said. In simplest terms, "they have to plan for what is now an inevitable death."
It is one of those facts that has to be accepted, Trojanowski said. "I would want to know if my dad or mother or wife is to die in five years," he said. "There are different arrangements than if they will live for 10 years."
There is a possible application of the finding about tau inclusions, said Dr. David M. Blass, director of the Frontotemporal Dementia Clinic at Johns Hopkins Medical Institutions. Studies to detect those inclusions could give information about the rate at which the condition would progress, he said.
"The importance of this study is that it looks at a very large group of patients that goes beyond any individual's clinical experience," Blass said. "For families with this condition, knowledge of prognosis is exceptionally important. Any improvement in the knowledge we can give families is of value in planning and making peace with the conditions of their loved ones."
Frontotemporal dementia is fully explained by Johns Hopkins University.