Area of Brain Hit Hardest by Parkinson’s Disease Pinpointed

Canadian researchers have pinpointed the part of the brain that appears most damaged by Parkinson’s disease and probably offers the best target for an experimental and controversial transplantation operation.

Researchers at the Clarke Institute of Psychiatry in Toronto examined the brains of eight patients who died from Parkinson’s disease. They found most of the damage appeared to be in a part of the brain known as the putamen.

As many as a million Americans suffer from Parkinson’s disease, which causes a devastating, progressive loss of muscle control due to a lack of the brain chemical dopamine.

Scientists had long known that cells in a part of the brain known as the striatum died from Parkinson’s disease. But the striatum includes sections known as the caudate and the putamen, and doctors were uncertain which was most affected.

In 1985, doctors in Mexico transplanted pieces of two Parkinson’s patients’ adrenal glands into the caudate sections of their brains, apparently improving their condition. Doctors believed that the adrenal tissue acted like tiny chemical factories, replacing the missing dopamine.

Since then, more than 50 Parkinson’s patients have undergone the operation in the United States, and the Mexican doctors have performed a similar operation using fetal brain tissue. Although the results have been mixed, doctors who performed the operation maintain that it appears to benefit at least some patients.

Dr. Stephen J. Kish, who headed the latest research, said he was skeptical about the operation’s benefits. But Kish said his findings indicate that it is more likely to be effective if the tissue is transplanted into the putamen.

“We’re suggesting that, logically, whatever implant is used should be directed to the putamen and not the caudate, which is what most surgeons have been implanting,” said Kish, who reported his findings in the New England Journal of Medicine.

Dr. Ray Watts, director of the Movement Disorders Program at Emory University School of Medicine in Atlanta, where seven patients have undergone the operation, said Kish’s findings do not necessarily mean that the caudate is the wrong place to transplant tissue.

Watts said researchers are uncertain why the operation works but speculated that the implantation of tissue into the caudate may produce unidentified growth factors that help surviving brain cells grow.