By David Chandler
Updated December 09, 1974 12:00 PM

The active ingredient in marijuana impairs the brain circuitry,” says Dr. Robert Heath. “We seem to be playing with dangerous, dangerous stuff.” That grim forecast may come as a shock to a country that was beginning to believe that pot was less harmful than alcohol. The public’s attitude toward the drug has softened so perceptibly in recent years that several state legislatures, as well as Congress, are considering measures that would minimize criminal penalties for possession of marijuana.

Dr. Heath, 59, of the Tulane Medical School in New Orleans, takes a hard line. His studies were among those cited by the White House adviser on drug abuse, Dr. Robert L. DuPont, when he took the official position last month that relaxing laws against marijuana would be very unwise. Citing a massive new Federal report titled Marijuana and Health, DuPont told a Senate subcommittee of new evidence that pot may cause lower male hormone levels in men, interfere with immunity mechanisms and affect the fundamental chemistry of living cells.

Dr. Heath’s research was aimed at discovering possible brain damage from smoking marijuana. In his pristine laboratory—which looks like the un-likeliest of toke rooms—13 rhesus monkeys have been turning on over the past four years. One rotating group represented “heavy smokers,” whose dosage was believed to be comparable to the three marijuana cigarettes smoked daily by some American troops in Germany. A “moderate” group of monkeys was given the equivalent of one joint a day, while a third group puffed away on inactive marijuana.

At first Dr. Heath attached electrodes to the monkeys’ scalps, but did not detect any abnormalities in their brain waves. But when he inserted silver-tipped electrodes deep into the hippocampus and the septal region of the brain—termed by neurologists the “pleasure center”—the electroencephalographs showed appreciable changes in the brain-wave patterns of the “stoned” monkeys. Observed Heath: “It appears that the active ingredient in marijuana, called Delta-9-THC, goes directly to the cell membranes of the emotional center. Temporarily it stimulates pleasure symptoms, but after repeated use it exhausts the pleasure chemicals of the brain.” The end result: “a reduction of interest and drive” (including the drives for food and sex) that lasts up to six months after the final smoke. As for the notion that pot is no worse than alcohol, Heath brands the comparison “ridiculous. Alcohol is a simple drug with a temporary effect. Marijuana is complex with a persisting effect.”

Psychiatrist Heath has carried out his marijuana research on a $140,000 grant from the National Institutes of Health, confirming his results with monkeys in a more limited way on human volunteers. One of the world’s preeminent experts on brain function, Heath is called the “father of organic psychiatry” by his colleagues for his work in the 1950s to isolate a protein, taraxein, from the blood of schizophrenics. Injected into monkeys or human volunteers, it induced schizophrenic symptoms. His first major breakthrough came in 1949, when he placed electrodes inside the heads of monkeys and began mapping out brain functions. Heath was also the first to plant electrodes deep into the human brain.

The chairman of the Department of Psychiatry at Tulane, Heath is so absorbed in his work that associates pin notes to his coat, reminding him to pay his income tax or shop on his way home for his wife, Eleanor.

Accustomed to controversy—the Freudians oppose Heath’s organic orientation in psychiatric thinking—the 6’3″, tanned and athletic scientist is prepared for the inevitable brouhaha over his findings. But the nonsmoking and teetotaling Heath (“I like my mind the way it is”) remains unfazed. “I personally don’t give a damn if people drink whiskey or smoke pot,” he shrugs, “but the facts should be out. Marijuana damages the brain.”