Gene Therapy Shows Promise for Parkinson's

Oct. 15 -- WEDNESDAY, Oct. 14 (HealthDay News) -- Macaque monkeys that received gene therapy for symptoms of Parkinson's disease saw a significant improvement in their motor function without the side effects associated with current standard therapy, researchers say.

Simultaneous insertion of three genes allowed certain cells in the brain to take over production of the neurotransmitter dopamine. Too-low levels of dopamine cause the hallmark motor-control symptoms of Parkinson's.

But even if this gene therapy approach were to someday produce good results in humans, it still would not solve many of the myriad other problems associated with Parkinson's.

Although tremors and other movement problems mediated by dopamine are characteristics of Parkinson's, people with the disease are also likely to develop dementia, behavior problems, depression, anxiety, heart problems, loss of the ability to smell, constipation and sexual dysfunction, most of which are not related to dopamine, said Dr. Fatta Nahab, assistant professor of neurology and director of movement disorder research at the University of Miami Miller School of Medicine.

"The studies that are being done are addressing the dopamine problem in Parkinson's and treating some of the movement-related symptoms," Nahab said. "That doesn't necessarily fix any of the other non-movement-related symptoms of Parkinson's, which can actually cause a greater amount of disability."

Dr. Bechir Jarraya, from the department of neurosurgery at Henri-Mondor Hospital in Paris and the study's lead author, said that the gene therapy would be considered a treatment rather than a cure because it "corrects only dopamine-related symptoms."

For the past 40 or so years, the treatment of choice for Parkinson's has been so-called dopamine replacement therapy, which uses drugs to increase dopamine levels in the brain.

The approach helps, but because the infusion of dopamine takes place in fits and bursts, not continuously, people often develop involuntary movements.