NEW YORK - Robert Ader, an experimental psychologist who was among the first scientists to show how mental processes influence the body’s immune system, a finding that changed modern medicine, died Dec. 20 in Pittsford, N.Y.
His death, at 79, followed a long illness and complications of a fracture suffered in a fall.
Dr. Ader spent his entire career as a professor at the University of Rochester School of Medicine and Dentistry, conducting some of the original experiments in a field he named himself, psychoneuroimmunology.
His initial research, in the 1970s, became a touchstone for studies that have mapped the vast communications network among immune cells, hormones, and neurotransmitters. It introduced a field of research that nailed down the science behind notions once considered magical thinking: that meditation reduces arterial plaque; that social bonds help cancer survival; that people under stress get more colds; and that placebos work on supposedly insentient cells.
At the core of Dr. Ader’s research was an insight already obvious to anyone who ever said, “Stop worrying or you’ll make yourself sick.’’ He demonstrated scientifically that stress worsens illness, sometimes even triggering it, and that reducing stress is essential to health care.
That idea, now widely accepted among medical researchers, contradicted a previous principle of biochemistry, which said that the immune system was autonomous. As late as 1985, the idea of a connection between the brain and the immune system was dismissed as folklore in The New England Journal of Medicine.
“Today there is not a physician in the country who does not accept the science Bob Ader set in motion,’’ said Dr. Bruce Rabin, founder of the Brain, Behavior, and Immunity Center at the University of Pittsburgh Medical Center. “He attracted interest in the field and made it possible to prove that mind-body is real.’’
Dr. Ader said his breakthrough began in 1975 with what he called “scientific serendipity.’’
He and a fellow researcher, Dr. Nicholas Cohen, were conducting an unrelated experiment about taste aversion involving rats and saccharine-sweetened water when they stumbled on a mysterious phenomenon.
One group of rats was given sweetened water and an injection that caused stomach aches. When the injections stopped and the rats that had experienced stomach aches refused to drink the water, researchers force-fed them with eye-droppers.
Dr. Ader and Cohen had expected the rats to refuse the drink. They had not anticipated that forcing them to drink would kill them, however, which it did, some time afterward.
The two guessed that the drugs in the injections may have had some bearing on the deaths. They had unwittingly picked Cytoxan, which besides causing stomach aches suppresses the immune system. They suspected that the rats had died from an overdose of Cytoxan. But the dosage the rats received was too low to support that explanation.
So they developed a theory, which proved correct: The rats died because the mere taste of saccharine-laced water was enough to trigger neurological signals that did indeed suppress their immune systems, as if they had been overdosed with Cytoxan. The rats succumbed to infections they were unable to fight off. It was the so-called placebo effect, only in this case it did not fool the brain into thinking it had been given something beneficial, but the opposite.
The findings were “incontrovertible,’’ Anne Harrington, a Harvard professor of the history of science, wrote in the 1997 book “The Placebo Effect.’’
“The fact that he had achieved this in rats, rather than humans, was a further blockbuster,’’ she continued, “because it undermined the frequent assumption that placebo effects were a product of peculiarly human interpersonal processes.’’
Robert Ader was born in New York City. He received his bachelor’s degree from Tulane University and, in 1957, his doctorate in psychology from Cornell.
His daughter Deborah, a psychology researcher, said modesty had been at the core of her father’s curiosity as a scientist.
He told her, “I didn’t know the immune system wasn’t supposed to be connected to the brain.’’