Leon Joel Thal, MD, distinguished professor and chair of neurosciences at the University of California, San Diego (UCSD) School of Medicine died on the night of February 3, 2007, when the single-engine plane he was piloting to his vacation home in Borrego Springs, California, crashed into a mountain. He was the only occupant of the plane. He was 62 years old.
Dr Thal was the acknowledged leader in the development of drug therapies for Alzheimer disease. Leon's medical school research had been on the enzyme that synthesizes the major brain neurotransmitter, acetylcholine. In 1976, the loss of this enzyme in the Alzheimer brain was discovered by others. Leon then began his search to find a way to provide relief to Alzheimer patients. His pioneer studies with oral physostigmine, a drug that blocks the breakdown of acetylcholine, and the collaborative investigation of the efficacy of tacrine that he led spurred the major drug companies to develop other cholinomimetic compounds that have become the standard symptomatic treatment in Alzheimer disease. Leon's keen interest in finding new classes of drugs to delay disease onset and improve the quality of life for his patients led to the formation of the Alzheimer Disease Cooperative Study. At the time of his death, 80 institutions were participating in this cooperative study.