A retrospective study indicates that children diagnosed with congenital esotropia (CET) over a 30-year period are nearly three times more likely to develop mental illness by their third decade of life than are children without strabismus.
Researchers investigated the prevalence of psychiatric disorders among young adults who had CET as children using data from the Rochester Epidemiology Project. The research team identified all patients younger than 19 years who resided in Olmsted County, Minn., and were diagnosed with CET between Jan. 1, 1965, and Dec. 31, 1994.
"We defined CET as a nonaccommodative esotropia that developed by age 6 months in a neurologically intact child. A total of 127 children, 67 males and 60 females, were diagnosed with CET in Olmsted County during the 30-year period," says Brian G. Mohney, M.D., with the departments of Ophthalmology and Pediatric and Adolescent Medicine at Mayo Clinic in Rochester, Minn.
Mental illness was defined as a disease meeting the Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR, Fourth Edition, criteria diagnosed by a psychiatrist, family physician or emergency physician. A history of mental illness diagnosed elsewhere was included when confirmed by a mental health care provider within Olmsted County.
The team then identified one age- and sex-matched control who did not have a diagnosis of strabismus for each case of CET. Cases were followed to an average age of 20 years (ranging from 6 months to 42 years old), compared with 19 years (ranging from 1 month to 58 years old) for the controls.
A mental health disorder was diagnosed in 42 (33 percent) of the children with CET, compared with 20 (16 percent) of the controls. A mental health disorder was diagnosed in 22 (33 percent) of the 66 males and 20 (30 percent) of the 61 females with CET. A diagnosis of CET increased the odds of being diagnosed with a mental illness by early adulthood 2.6 times.
"Cases with CET were more likely than their controls to have a greater number of mental illness diagnoses and use psychotropic medications. Individuals with CET were also more likely to have been born prematurely or have had some difficulty with pregnancy, although premature birth did not seem to significantly alter mental health outcomes," says Dr. Mohney.
The most commonly diagnosed forms of mental illness disorders among males were major depression, attention-deficit/hyperactivity disorder, substance abuse and alcohol dependence. Among females, the most prevalent forms of mental illness disorders were major depression, depression not otherwise specified, adjustment disorder and eating disorders.
"Although the sample size of individual mental health disorders was too small to demonstrate statistical significance, these findings do expand further the forms of childhood strabismus associated with the subsequent development of mental illness," says Dr. Mohney. "Previously, intermittent exotropia and convergence insufficiency were associated with an increased risk of developing mental illness. Until we extended the cohort to 30 years, cases with CET were found to have no greater risk than controls."
The increased risk of developing mental illness by early adulthood among children with CET may be explained by environmental factors. Hereditary factors also may play a part in the development of mental illness among children with CET. "Future studies may explore those factors. The findings from this study, which were published in Ophthalmology in 2012, may also raise questions regarding the prevalence of mental illness among young adults," says Dr. Mohney. A rate of 16 percent among controls in this study is consistent with reports that indicate mental illness occurs in 15 to 30 percent of young adults. Strabismus affects 3 to 5 percent of children worldwide.
Olson JH, et al. Congenital esotropia and the risk of mental illness by early adulthood. Ophthalmology. 2012;119:145.