Dr. Leon Thal, a UC San Diego professor who was one of the world's leading investigators of new therapies for Alzheimer's disease, died in a plane crash Saturday near Borrego Springs, Calif. He was 62.
Thal was an avid flier who had taken off from Montgomery Field in San Diego at 6:15 p.m. Saturday for the half-hour flight to Borrego Springs. Thal's wife reported him missing shortly before his plane's signal was detected at 7:39 p.m. by the rescue coordination center at Langley Air Force Base, Va., said Ian Gregor, a spokesman for the Federal Aviation Administration in Los Angeles. A rescue team later recovered Thal's body in his plane, a Mooney M20J, in a mountainous area eight miles southwest of Borrego Springs. The crash is under investigation by the National Transportation Safety Board.
Thal was passionate about flying, a hobby that provided relief from the challenges of his work. He told the San Diego Union-Tribune a few months ago that he had flown his plane from Iceland to Scotland once and across the United States seven times.
What wrested most of his attention was fighting Alzheimer's, a degenerative brain disease with no known cure that afflicts 4.5 million Americans, destroying the memory of its victims in stages.
He was director of UC San Diego's Shiley-Marcos Alzheimer's Disease Research Center, which was established in 1984 as one of the original five centers supported by the National Institute on Aging.
Since 1994 he had also headed the Alzheimer's Disease Cooperative Study, a consortium of 80 clinical sites in the United States and Canada that conduct research on potential treatments for the disease.
"He was the catalyst who brought big groups together to work on very complex problems," said Dr. William Thies, vice president of medical and scientific relations for the Chicago-based Alzheimer's Assn.
"He was a terrific scientist," Thies added, "but I think one of his great contributions to the field was that he made everyone around him better. He could get people to work together ... which is not always easy. He had a wonderful touch with people."
Thal's fascination with Alzheimer's disease began 30 years ago, when he began studies that led him to focus on the role of the chemical transmitter acetylcholine in learning and memory. That work led him in 1983 to publish some of the first evidence that memory could be enhanced in Alzheimer's patients by inhibiting production of a brain enzyme called cholinesterase. This finding provided the basis for the first approved drug to stall the progression of Alzheimer's.
He later was involved in studies that disproved the benefits of ginkgo biloba, an herbal remedy, and estrogen replacement therapy, both treatments that were widely believed to boost memory. He also helped oversee work that showed a modest benefit to Alzheimer's patients who took prescribed doses of vitamin E.
More recently, Thal was evaluating lithium, intravenous immunoglobulin and an omega-3 fatty acid in fish oil called docosahexaenoic acid, or DHA.
Thal "led us to a greater understanding of what might work, what doesn't work and where future research has to go to develop better therapies," said Dr. Mark Tuszynski, vice chairman of UC San Diego's Department of Neurosciences, who knew Thal for 20 years.
Tuszynski said Thal's "towering achievement" was building the Alzheimer's Disease Cooperative Study, launched in 1991 with an $18-million grant from the National Institute on Aging. Since then it has attracted $100 million in funding.
It conducts clinical trials at various institutions and provides a central database housed at UC San Diego, where results are assessed according to rigorous standards. An important part of the consortium's mission has been to analyze widely available substances, such as fish oil and vitamin E, that are not profitable enough for pharmaceutical companies to test.
Under Thal's leadership, the consortium has "allowed successful tests of many treatments more rapidly and effectively" than any single institution or research group could accomplish on its own, said Dr. Richard J. Hodes, director of the National Institute on Aging in Bethesda, Md.
Tuszynski and others said that Thal's work has shown researchers the best ways to structure clinical trials of potential Alzheimer's treatments and properly measure benefits. He led a team of investigators at UC San Diego that developed memory tests that more accurately gauge the progression of the disease and have contributed to scientists' overall understanding of how it attacks cognitive function.
Thal, a native of New York City, earned his medical degree at Downstate Medical Center, part of the State University of New York, in Brooklyn. He completed his residency nearby at Albert Einstein College of Medicine and was teaching there when he was recruited to UC San Diego in 1985 as an associate professor. He became chairman of the neurosciences department in 1993.
In 2004, he won the Potamkin Prize, one of neuroscience's highest honors and the most prestigious award in the field of Alzheimer's research. He shared the $100,000 prize with Dr. Roger Nitsch of Switzerland.
He was disappointed that research efforts so far have produced treatments with only modest benefits to Alzheimer's patients. But he told the Union-Tribune in October that he believed new therapies would be developed in his lifetime that would delay the most debilitating aspects of the disease by five or 10 years.
"This has turned out to be a much more difficult disease than anybody imagined," he said. "People with this disease shouldn't have to get worse."
He is survived by his wife, Donna Thal, a professor emeritus at San Diego State University. A memorial service is pending.