Youth Depression Tied to a Wide Range of Illnesses, Early Death

Children and adolescents with depression may be at dramatically increased risk for premature death or an array of diseases later in life, new research suggests.

Youths with depression had a significantly increased risk for being diagnosed with any of 66 medical conditions later in life. The greatest increased risk was for self-harm; the rate was 14-fold higher rate among those who had experienced depression in childhood or adolescence compared to those who had not.

There was an eightfold increase in the risk for sleep disorders, a sixfold increase in the risk for viral hepatitis, and an almost fourfold increase in the risk for type 2 diabetes.

Moreover, those who had experienced depression in youth were nearly six times more likely to die prematurely compared to the general population.

"Depressed children and teenagers have an increased risk of suffering from premature death and a wide range of illnesses later in life," senior author Sarah Bergen, PhD, associate professor, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden, told Medscape Medical News.

"We would like clinicians to be aware of this association so they can monitor young patients with depression for other health outcomes," she said.

The study was published online December 9 in JAMA Psychiatry.

Later Impact

"There are many studies showing that depression and other diagnoses co-occur, but most of these involved adults and only [focused on] a small number of other disorders," Bergen said.

"Since experiences early in life may have significant later impact, we investigated whether childhood and adolescent depression was related to experiencing a large range of possible outcomes," she added.

The researchers drew on data from Swiss national registers encompassing 1,487,964 individuals born between 1982 and 1996. Participants were followed through 2013.

Of these persons, 2.5% (n = 37,185; 67.4% female) experienced depression (defined as receiving one or more diagnoses of depression between ages 5 and 19 years). Over half (60%) of patients with depression received their first diagnosis between ages 17 and 19 years.

The researchers identified 69 somatic illnesses, which they grouped into 14 categories: infections; immune dysfunction; autoimmune diseases; endocrine and metabolic disorders; nervous system diseases; eye diseases; circulatory system diseases; respiratory system diseases; digestive diseases; musculoskeletal system and connective tissue diseases; genitourinary system diseases; diseases during pregnancy and the perinatal period; and injuries.

They grouped cause of death into three categories: death by intentional self-harm, death by external causes, and death by natural causes.

Psychiatric comorbidities that were diagnosed during follow-up were categorized as substance use disorders (SUDs); anxiety disorders; earlier-onset disorders (attention-deficit/hyperactivity disorder [ADHD], autism spectrum disorders, and intellectual disability); and later-onset disorders (mania, bipolar disorders, schizoaffective disorders, and schizophrenia).

Females More Vulnerable

The prevalence of comorbid psychiatric disorders was higher among youths with depression than in the general population.

During the follow-up period, 1% of patients who experienced depression as youths died, compared to 0.4% in the nondepressed group. Intentional self-harm was the leading cause of death among those who had experienced depression as youths, followed by other external causes of death. By contrast, most individuals without depression died from external or natural causes.

For both sexes, persons who experienced depression as youths had almost six times the risk for all-cause mortality compared to individuals who had not been diagnosed with depression as youths (HR, 5.9; 95% CI, 5.3 – 6.6). The greatest risk was associated with intentional self-harm (HR, 14.6; 95% CI, 12.6 – 16.9), followed by death from other external causes (HR, 3.7; 95% CI, 3.0 – 4.6) and death by natural causes (HR, 2.1; 95% CI, 1.6 - 2.9).

"Our study does not show that [youth] depression causes the later conditions, only that there is an association, for which there are several potential explanations," Bergen said.

"It is possible that genetic or environmental risk factors lead to both youth depression and somatic diseases. Alternatively, depression may alter biological mechanisms in ways that are detrimental to overall health later in life, or depression may increase risks for poor health behaviors that lead to these associations," she suggested.

"Canary in a Coal Mine"

Commenting on the study for Medscape Medical News, Gabrielle A. Carlson, MD, professor of psychiatry and pediatrics, Renaissance School of Medicine at Stony Brook University, Stony Brook, New York, acknowledged being "surprised by the variety of medical illnesses that seemed to have some association with earlier-onset depression."

Carlson, who is the president of the American Academy of Child and Adolescent Psychiatrists and was not involved with the study, said that what "made this study particularly interesting is that they [the researchers] looked at kids who were not yet sick and did not yet have these illnesses but are at risk for them downstream.

"Depression can be seen as a 'canary in a coal mine,' noting that individuals who develop depression at an early age are at risk for difficulties in the future, not least of which are medical illnesses," Carlson added.

The study was funded by the European Union's Horizon 2020 Research and Innovation Programme. Bergen reports no relevant financial relationships. The other authors' disclosures are listed on the original article. Carlson has disclosed no relevant financial relationships.