Study Raises Estimates Of Mentally Ill Youth

Several new findings from the seven-year Great Smoky Mountain Study (GSMS) have led researchers to conclude that a higher number of children reach adolescence with psychiatric disorders than experts had estimated previously on the basis of a patchwork of studies.

The results, reported in the August Archives of General Psychiatry, show that by the time children in the study reached age 16, 1 in 3 had or had had at least one psychiatric disorder, and as children grew older, psychiatric disorders were more likely to be accompanied by significant functional impairment.

While girls had higher rates of anxiety and depressive disorders, boys had significantly higher rates of behavioral disorders, especially conduct disorder.

Furthermore, 1 in 4 children diagnosed with a psychiatric disorder during the study had two or more comorbid disorders. Depression was linked with conduct disorder in girls, while depression was linked with substance abuse disorders in boys.

A randomized multistage study of 1,420 children and adolescents residing in western North Carolina was conducted between 1993 and 2000. Three cohorts of children were recruited at ages 9, 11, and 13 and assessed yearly until age 16. Both parents and children were interviewed yearly during the study.

The researchers, who are in the departments of psychiatry and behavioral sciences and biostatistics and bioinformatics at Duke University Medical School, used the Child and Adolescent Psychiatric Assessment (CAPA) developed by psychiatrist and co-investigator Adrian Angold, M.D., and psychologist and principal investigator Jane Costello, Ph.D.

The CAPA measures three-month prevalence rates because the researchers found that memory recall of symptoms decreased after three months. The CAPA is compatible with DSM-IV criteria and is considered by research experts to be a valid, reliable instrument.

Costello and her colleagues predicted in a 1996 article, based on the first wave of data from the GSMS study, that 1 in 6 children would have at least one psychiatric disorder by age 16. When the second wave of data was available in 2000 and analyzed, the authors revised their original prediction to about 1 in 3 children.

Peter Jensen, M.D., director of the Center for the Advancement of Children’s Mental Health in New York City, commented to Psychiatric News that Costello’s finding is similar to that of Ronald Kessler, Ph.D., and his colleagues; they conducted the National Comorbidity Survey of 15- to 54-year-olds published by the Archives in 1994. The authors found that up to 30 percent of 15-year-olds had one or more psychiatric disorders.

“Globally, clinicians are reporting higher rates of depression and behavioral disorders in youth than in the past decade. This may reflect better diagnostic tools and the cohorts’ age difference,” said Jensen.

The researchers found that “[o]nce children, particularly girls, develop a psychiatric disorder, their chances of continuing to have one, or of developing another episode after remission, are much higher than those of their unaffected peers.” A pattern of having the same disorder diagnosed at various points in time was significant for all disorders except specific phobias.

Costello told Psychiatric News, “I was surprised by how much continuity there was among diagnosed psychiatric disorders except for specific phobias. This homogeneity was greater in girls than in boys.”

In contrast, a pattern of having a psychiatric disorder with a different diagnosis over time was less common but was more likely to occur in girls. For example, girls diagnosed with anxiety disorder were more likely to develop a substance abuse disorder, said Costello.

“This suggests that the DSM-IV criteria may fit boys’ developmental patterns more than girls’. There is no similar evidence suggesting that boys with an emotional disorder were at an increased risk for a behavioral disorder or vice-versa,” said Costello.

David Shaffer, M.D., a psychiatrist and expert on mood disorders in youth, commented, “I found the paper interesting not because the numbers were very different from what others had reported, but because it illustrates the way disorders unfold, taking into account common comorbidities that exist for many important disorders.”

He continued, “We know that anxiety and depression often co-occur and one precedes the other, but this study shows the bidirectional movement between the disorders and how they oscillate between one another over time.”

Shaffer also commented on the connection between anxiety and substance abuse. “The paper, while not fully exploring this, does cast light on the old idea that depression predisposes someone to substance abuse. Self-medication with substances for anxiety makes a whole lot more sense than self-medication for depression because so many substances do relieve anxiety, while it is unclear that they relieve depression.”

The abstract of Costello’s study is posted on the Web at http://archpsyc.ama-assn.org/cgi/content/abstract/60/8/837. ▪

Arch Gen Psychiatry 2003 60 837