As experts become convinced that many mental disorders begin in childhood and adolescence, responsibility for recognizing problems is shifting to parents, teachers, pediatricians and youth counselors.
But researchers can give adults only vague guidelines to help them assess whether children are at risk for mental disorders or show symptoms of an emerging problem.
Researchers, for example, know that genetic factors are linked to autism and some learning disabilities; that head injury or exposure to toxic substances puts some children at risk for behavior disorders; that psychological trauma, such as physical or sexual abuse, increases the risk of such mental illnesses as multiple-personality disorder.
But, says Michael Goldstein, of the UCLA department of psychology, "These risk factors need to be honed down to those that have high reliability and high predictability. I'm not sure we're there yet."
Experts often group risk factors for mental disorders into four areas:
* Biological risk factors, including genetic defects; very low birth weight; chronic physical conditions, such as deafness or blindness; illness, such as diabetes or asthma; physical trauma, or exposure to toxic chemicals or drugs.
* Psychological risk factors, including low intelligence, learning difficulties and deficits in sensory perception.
* Social risk factors, including poverty, homelessness, over-crowded living conditions, inadequate schooling, neighborhood disorganization and poor peer relations.
* Familial risk factors, including poor prenatal care, a very young or mature mother, parental criminality, maternal mental disorder, severe marital discord, poor parental supervision, erratic discipline, child abuse and placement of a youngster in a series of foster homes.
But much research remains to be done before the association between these risk factors and the emergence of a mental disorder can be understood.
While many mental disorders are thought to have a biological cause, little is known, for example, about which genes might predispose an individual to a particular disorder, says Dr. James F. Leckman, a child psychiatrist at Yale University. Technological skills to understand genetic defects are within reach, he says, but little research is directed at causes of child psychiatric disorders: "There are fewer than 100 child psychiatrists in the nation who devote 30% or more of their time to research."
Leckman blames the low priority given to child psychiatric research to the stigma associated with mental disorders; the relatively low status of professionals working with children, especially impaired children, and the fact that the field of mental health is overwhelmed with providing services for the ill, leaving little time for basic research.
Research into the social and familial risk factors is equally vague, says Gail Wyatt, who studies psychological effects of childhood physical and sexual abuse at UCLA's Neuropsychiatric Institute.
Abused children tend to develop sleeping and eating problems, withdraw from friends and have problems concentrating in school. Girls tend to become depressed and withdrawn while boys act out. "Children are often punished, rather than treated, for their mental health problems," she says. "But these are classic mental health problems that in the past have not been associated with sexual abuse."
Children with low intelligence or learning disabilities are also vulnerable to mental disorders, says Claire Kopp, a developmental psychologist at UCLA. Cognitive problems can lead to aggression, conduct disorders and psychosis.
"These children are greatly neglected because there are many complexities involved," she says. "They tend to fall through the cracks because they are so easy to miss in terms of mental disorders."
Also far from clear is how certain family relationships and problems affect children, Goldstein says. "It has been difficult until recently to obtain clear-cut evidence about the type of family disturbances that cause problems," he says. "Some children are more vulnerable than others. Some family disturbances are more toxic than others."
In general, the risk of having a mental disorder increases with the number of risk factors. One study found that the likelihood of having a mental disorder increased tenfold when four or more risk factors were present.
Children with cognitive difficulties often fare worse, for example, when adverse rearing conditions are present, Kopp says. And depression is increasingly seen by experts as a precursor to substance abuse.
One study showed that a major depressive episode among 18- to 30-year-olds doubles the risk of subsequent drug abuse.
"It's usually the behavioral problems that start first," says Dr. Adrian Angold, a Duke University researcher. "These kids do not just have substance abuse problems, they have a variety of emotional and behavioral problems as well. If we focus just on substance abuse, we're missing the point. We need to start before the individual has even seen alcohol."
Besides pinpointing the predictability of risk factors, researchers are trying to learn more about "protective factors" that seem to make some children immune to psychological injury no matter what they experience in life.
Although less well-understood, these factors are thought to include: early prenatal care, good maternal nutrition, a loving relationship with at least one parent or other adult, consistent parental supervision and discipline, cognitive training, social skills training and improved peer relations.
"What we're learning . . . is how to tie together risk and protective factors with specific disorders," says Dr. Felton J. Earls, a professor of child psychiatry at Harvard. "We're beginning to make some progress. We have to understand something about timing and the combination of risk factors."