Hereditary factors are partly responsible for childhood anxiety and depression that persists into adulthood, according to University of Queensland researchers. The largest study of its kind in the world looked at genetics from more than 65,000 children, aged between three and 18 years.
It’s the first time researchers have conducted such a large-scale study examining the role of genetics in repeated measures of anxiety and depression, both internalizing disorders, in children.
The study was published in Journal of the American Academy of Child & Adolescent Psychiatry late last month. The data were from the Early Genetics and Lifeforce Epidemiology consortium.
Christel Middeldorp, who holds a co-joint appointment with the UQ Child Health Research Centre and Children’s Health Queensland, said the study showed children who had similar levels of anxiety and depression were also alike genetically.
“It also revealed a genetic overlap between childhood and adult mental health disorders when comparing the results in this childhood study with results of previous studies in adults.”
In 22 cohorts, multiple univariate genome-wide association studies (GWASs) were performed using repeated assessments of internalizing symptoms in 64,561 children and adolescents between three and 18 years of age. Results were aggregated in meta-analyses that accounted for sample overlap,
“These findings are important because they help identify people most at risk of symptoms continuing across the lifespan, so intense treatment can be provided where needed,” Middeldorp said.
Internalizing disorders are substantial contributors to the global burden of disease. As the authors note, “Although the estimated 12-month prevalence of depression and anxiety disorders in adults is 15%, internalizing disorders are also present in early life, with an estimated prevalence of 2% to 3% of depression and 6% to 7% of anxiety in childhood and adolescence. Prior to the diagnosis of internalizing disorders, as many as one in five children self-report internalizing symptoms.”
Early symptoms of anxiety and depression may pose a long-term risk, as they can be associated with mood disorders, anxiety, and suicidality in adulthood.
Middeldorp said genetic variants needed to be investigated because they increased the risk of recurrence and co-occurrence with other disorders.
“Mental health symptoms often come together, so those who experience anxiety or depression have a greater risk of disorders such as ADHD, aggressive behavior,” she said. “We found that this co-occurrence is also due to genetic variants” she added.
Genetics account for around 40% of a person’s risk of suffering anxiety and depression, with environmental factors accounting for the rest.
Middeldorp said while everyone could feel anxious or depressed from time to time, some people were better able to adjust to life’s circumstances.
“People with an anxiety disorder ruminate about their situation, preventing them from moving on,” she said. “There is a difference in how people respond to stressors, and part of that difference is genetic.”
The authors note that the first GWASs studies on childhood internalizing symptoms, published in 2013 and 2014, did not identify any genome-wide significant hits for maternal-reported anxiety-related behaviors in children seven years of age (N = 2,810) or internalizing problems in children three years of age (N = 4,596).
Researchers will now analyze the interplay of genetics and environmental variables, such as school and family life, to see how together they influence childhood anxiety and depression.
The authors conclude that genetic correlations suggest childhood and adolescent internalizing symptoms share substantial genetic vulnerabilities with adult internalizing disorders and other childhood psychiatric traits. That could help explain both the persistence of internalizing symptoms over time and the high comorbidity among childhood psychiatric traits.
