THE ANGUISH that leads to suicide seems to follow no set path. But researchers believe they are making important progress toward understanding that painful process.
They have identified a deficiency of a specific chemical--serotonin--in the brains of some people who are prone to take their own lives in the face of life`s difficulties.
Some researchers believe as a result that biological factors may play a far greater role in the events that end in suicide than has been realized. And the hope now is that a drug could eventually be developed to correct the chemical deficiency and prevent at least some future suicides.
``A low level of serotonin seems to be a biochemical marker for those depressed people who are most prone to suicide,`` according to Herman van Praag, a psychiatrist at the Albert Einstein College of Medicine.
Other researchers, though, continue to place their greatest emphasis on psychological factors and, in particular, on what they see as a lethal combination of rigid thinking and feelings of loss and hopelessness.
A recent study found, for example, that an intense level of hopelessness felt by those who had made one attempt at suicide was by far the strongest indication that they would try again.
Many observers believe there can be no single explanation of why people take their lives. ``Suicide is a complex malaise,`` said Edwin Shneidman, a pioneer in suicide research who is professor of thanatology at the UCLA School of Medicine. ``Sociologists have shown that suicide rates vary with factors like war and unemployment; psychoanalysts argue that it is rage toward a loved one that is directed inward; psychiatrists see it as a biochemical imbalance. No one approach holds the answer: it`s all that and more, including an existential dilemma.``
``Suicide is mainly a problem among white, older men,`` said Susan Blumenthal, director of the suicide research unit at the National Institute for Mental Health. The average for all groups is about 12 in 100,000. But it has been generally declining since 1950, especially for those over 44 years old.
Young people represent the chief exception to the trend, and their increased rate has of late received widespread attention. In the 1970s, the suicide rate doubled for white males from 15 to 24 years old. The rate has also risen for young black men, to over 20 in 100,000 among those 25 to 34 years old. This is the highest for any age group among blacks, who overall have lower suicide rates than whites.
Still, overall rates remain highest among the elderly, said Lee Robins, a psychologist at Washington University Medical School, in St. Louis. The rate for those 75 or older is still more than three times the rate of that among the young.
For women, it is about 3 in 100,000, about a quarter of the overall average, said Dr. Blumenthal.
``Even though they are much less likely to take their own lives,`` she said, ``women are four times more likely than men to make an unsuccessful attempt. For women, attempts often are a way to express their distress, something men may be less able to do until the pain has gotten too great.``
Another key factor in the higher rates for men, she believes, may be what psychiatrists have found to be a tendency toward impulsive violence, a trait that may have a biochemical basis. She points to the new research suggesting a strong relationship between suicide and low levels of serotonin.
Serotonin, one of dozens of neurotransmitters that control the activity of brain cells, is instrumental, along with other brain chemicals, in regulating certain brain activities, including emotion.
Using new techniques, investigators have been able to find serotonin deficiency by measuring levels of one of its main metabolic products, a chemical with the formidable name 5-hydroxyindoleacetic acid, abbreviated as 5-HIAA. Researchers can determine levels of 5-HIAA in the brain during autopsies, and from spinal fluid drawn from the living.
The current research on serotonin was sparked by a finding by Marie Asberg, a psychiatrist at the Karolinska Institute in Stockholm. While studying depression, she and her co-investigators found that 40 percent of a group of depressed patients who had lower than normal levels of 5-HIAA had attempted suicide. Among depressed patients with normal levels of 5-HIAA the suicide rate was just 15 percent, Dr. Asberg reported in the Archives of General Psychiatry in 1976.
Moreover, the attempts by those in the group with less 5-HIAA were more serious and violent, such as jumping from buildings and gunshots, than those by the other group of patients, all of whom had resorted to drug overdoses.
Dr. Asberg has also found that among patients who had been hospitalized for suicide attempts those with low levels of 5-HIAA were 10 times more likely to have died from suicide after one year than were those with low levels.