The psychiatrist who proved that a drug could help manic-depression and three molecular geneticists who showed that genes control a part of the immune system are the winners of the 1987 Albert Lasker Medical Awards, the Lasker Foundation will announce today.

Dr. Mogens Schou, a psychiatrist who is research director of the Psychopharmacology Research Unit at Aarhus University Institute of Psychiatry in Riskov, Denmark, was honored for demonstrating that lithium is an effective treatment for manic-depressive illness -- one of the most common mental disorders worldwide.

Drs. Susumu Tonegawa of the Massachusetts Institute of Technology, Philip Leder of the Harvard Medical School and LeRoy Hood of the California Institute of Technology will receive awards for their independent but closely related work on the immune system.

The Lasker award, which has been presented annually for 42 years, is considered by scientists as a stepping stone to the Nobel prize, the highest honor in biomedical research. In fact, 44 of the 130 Lasker award winners have also won the Nobel prize in medicine.

This year's winner, Schou, has spent 15 years studying the effects of lithium on manic depression. Estimates are that manic-depressive disease afflicts 1 to 2 percent of the world population. In the United States alone, an estimated 800,000 to 1.2 million Americans suffer from this mental disorder, according to the National Institute of Mental Health.

Manic-depressive disorder puts patients on an emotional rollercoaster that takes them through a period of mania, where they feel as though they can accomplish anything, and then plummets them later to the depths of depression. During the manic phase, people with this disease often work round-the-clock and talk incessantly. Suddenly, their mood changes. During the depressive period, patients are at high risk of committing suicide.

As part of the research, Schou (pronounced skow) conducted double-blind studies in which half of patients received a placebo (or sugar pill) and half received lithium. Results showed that lithium protected patients from recurrences of both depression and mania.

"By providing the clinical evidence that established lithium as the treatment of choice for manic-depressive illness, Dr. Schou had a profound impact on a major cause of human suffering and disability," said Dr. Michael E. DeBakey, chancellor of the Baylor College of Medicine in Houston and chairman of the Albert Lasker awards jury.

Equally important, DeBakey said, is that Schou's work "started a revolution in the approach to mental disorders" by suggesting to researchers that mental illnesses could be the result of biochemical imbalances in the brain.

Calling Schou's work a "hallmark," Dr. Herbert Pardes, director of the New York State Psychiatric Institute and former director of the National Institute of Mental Health, said that the use of lithium "has helped all kinds of people who would have otherwise had disastrous lives."

In the rapidly changing field of molecular genetics, Tonegawa, Leder and Hood have all investigated the role that DNA -- the genetic script that forms blueprints of life -- plays in regulating the immune system, the body's first line of defense against disease.

Scientists have known that DNA is ultimately responsible for producing a changing array of antibodies -- proteins that help target foreign invaders for destruction by white blood cells, the so-called foot soldiers of the immune system. But it was Tonegawa, a professor at MIT's Center for Cancer Research, who showed how the body is able to produce such a wide variety of protective antibodies. Tonegawa found that the genes for producing antibodies are inherited as partly finished genes, which are then "reassembled in very large numbers of different combinations during an individual's lifetime to protect against disease," he said.

Each time these rearrangements occur, there is a chance that other changes will happen as well. These extra changes are called random mutations, and they increase the odds that the immune system will produce an antibody that can identify and neutralize the widest possibility of disease-causing organisms.

In related work, Leder, who is chairman of Harvard Medical School's Department of Genetics, has shown that these rearrangements of genes can sometimes go awry and cause cancer instead of new antibody production. In studies of white blood cells known as B cells (which make antibodies), Leder found that a misplaced gene is responsible for causing Burkitt's lymphoma -- a cancer of the B cells. "The recombination mechanism, which is vital to the immune system, can become involved in cancer when it is not properly regulated," he said.

But when the system works properly, it allows the body to make almost an infinite array of antibodies, which in turn makes the body better able to fight disease. The work of Cal Tech's Hood, who is chairman of Cal Tech's department of biology, helps explain how the body is able to make such a diverse array of antibodies to fight disease.

Hood has found that the DNA, working through genes, governs the production of certain parts of the antibody, called heavy and light chains. Constant rearrangement of the genes varies the chains in the antibodies, which in turn varies the structure of the antibodies themselves.

"This system is one of the most elegant in all biology and yet it requires only a minimum of genetic information," said Hood. "No scientist could imagine a better way to make lots of different sizes and shapes of antibodies."

Hood and the other winners will receive their awards, which include a $15,000 honorarium, Nov. 18 at Rockefeller University In New York City.