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Where Does Your 'Self' Live?

Scientists find the seat of the personality

TUESDAY, May 8 (HealthScout) -- The part of ourselves that loves roses, hates broccoli and tells a great joke -- our personality -- may originate in a specific spot in our brain, new research shows.

A California researcher has found that most of his patients who have a particular kind of brain disorder and dramatic personality swings also have the most damage from the disease in their right frontal lobe, the part of the brain behind the forehead.

He says the findings could lead to a new understanding of frontotemporal dementia and a better awareness of the anatomy of what makes up the self in general.

"It was my attempt to understand a series of very puzzling changes in my patients with frontotemporal dementia," says lead author Dr. Bruce Miller. "I was trying to get at the mechanism of these changes. It's a very preliminary study, but I think it will stand the test of time."

Another expert agrees the findings could lead to new treatments.

"I think it's fascinating," says Dr. Mario Mendez, a professor of neurology and psychiatry at the University of California, Los Angeles, and director of the Frontotemporal Dementia Clinic there. "The first step in understanding any disease is discovering the underlying process so we can start to think about behavioral and pharmacological treatments."

Frontotemporal dementia is a degenerative and possibly genetic condition involving the front part of your brain. This is the area that controls reasoning, personality, movement, speech, social graces, language and some aspects of memory.

The disorder affects 2 percent to 5 percent of the 7 million Americans who suffer from some sort of dementia. Unlike Alzheimer's disease, this dementia does not translate into severe memory loss. It occurs equally in men and women between the ages of 40 and 65. Its hallmark is changes in personality and behavior. In the disease's late stages, patients can't move and lose the ability to talk or express themselves.

There is no cure or treatment for frontotemporal dementia, although research has shown that drugs called serotonin inhibitors may help with some of the compulsive and anti-social behaviors that can crop up.

"Right now, we don't have good treatments for this disease," Miller says.

Miller explains he first decided to look at where a person's sense of self may be located in the brain after he noticed several of his patients with frontotemporal dementia suddenly changed their political and religious beliefs, along with the food they ate and the clothing they wore.

"It's so unusual to see people in midlife change these things so completely," he explains.

So, researchers examined 72 patients with frontotemporal dementia. Those patients were evaluated for marked changes in their "self." MRIs and single photon emission computerized tomography (SPECT) images were used to figure out which areas of the brain had been most damaged by the disease.

What they found in the seven patients who had profound personality changes was that the right frontal lobe was the most damaged. Only one of the seven had the most damage in the right temporal lobe. This lobe is slightly beneath the frontal lobe, in the area in back of the temple. Of the 65 patients who kept their sense of self intact, only one had most of the disease damage in the right frontal lobe.

Mendez notes that Miller's work and other studies have shown that the right frontal lobe region "has a great deal to do with the personal reference of a person. This is really important, discovering that certain social behaviors are affected by brain disease."

Miller says further study is underway to look at families that have more than one member with frontotemporal dementia. With almost half of these patients, another close relative, like a sibling or parent, also has the disease. And new research has pointed to the mutation of a specific gene, called tau, or chromosome 17q21-22, as a possible cause of the disease in these instances. That could lead to new treatments within the next decade, Miller says, with medicines targeting sites in the right frontal lobe.

Miller also notes that doctors might want to take heed of the fact that the right frontal lobe may be the place where personality is located, since most brain biopsies are done in that part because it is considered a non-linguistic, non-eloquent part of the mind.

"Social behavior is very eloquent. They might want to rethink that," he says.

As a matter of fact, many psychiatric disorders could be looked at in a new light now that research is finding personality originates in a specific part of the brain, he adds.

"It probably has implications for psychiatry and all kinds of personality disorders," he says. "Thinking about the anatomy of the self is very exciting."

Mendez puts it this way: "If we're ever going to understand people like Timothy McVeigh, I think we have to understand what these brain relationships are." McVeigh is to be executed May 16 in the federal prison in Terre Haute, Ind., for the 1995 Oklahoma City bombing that killed 168 people.

What To Do

For more on frontotemporal dementia, visit the Family Caregiver Alliance or the Alzheimer Society of Canada. For clear views of these areas of the brain -- and much more -- explore the Traumatic Brain Injury Resource Guide.

Or, take a look at these HealthScout stories for more on dementia.

SOURCES: Interviews with Bruce Miller, M.D., A.W. Clausen professor of neurology, University of California, San Francisco; Mario Mendez, professor, neurology and psychiatry, University of California, Los Angeles, and director, Frontotemporal Dementia Clinic, UCLA; May 8, 2001 presentation, annual meeting, American Academy of Neurology, Philadelphia, Pa.
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