Childhood 'Bridge Symptoms' May Predict Adult Depression

George W. Citroner

September 11, 2018

For the first time, researchers have identified "bridge symptoms" in childhood that could be central indicators of anxiety or depressive disorders in later life.

In the population-based study, investigators examined the network structure of emotional and behavioral symptoms among elementary school-aged girls in Quebec, Canada. They discovered that bridge symptoms, such as irritability and rejection, were associated with the development of anxiety disorders or major depression in early adulthood.

Lead author Alexandra Rouquette, MD, PhD, Paris-Saclay University, France, noted that several mental disorders are among the top 20 causes of global disease burden.

"A recent evaluation of the global burden specific to mental illness revealed a distant first rank in terms of years lived with disability compared to other diseases, and a nearly joint first with cardiovascular diseases in terms of disability-adjusted life-years," Rouquette told Medscape Medical News.

"Enhancing the understanding of the emergence of mental disorders is therefore fundamental to design prevention programs which could efficiently reduce their incidence," she added.

The findings were published online August 15 in JAMA Psychiatry.

Growing Number of Clues

Previous studies have shown an association between high levels of affective problems in childhood and depression and/or anxiety disorders in adulthood. Links between externalizing behaviors in childhood and disruptive disorders in adulthood have also been observed, Rouquette noted.

"There are a growing number of clues in the literature that suggest that the onset of adult psychopathologic disorders can be traced back to behavioral or emotional symptoms observed in childhood or adolescence. Targeting early childhood symptoms might thus be effective in preventing future mental disorders," she said.

She cautioned that these interventions are challenging to implement because "we lack knowledge on which specific childhood symptoms have predictive associations with adult psychopathologic disorders."

In the current study, the researchers used data from an ongoing longitudinal prospective analysis of kindergarten children in the Canadian province of Quebec to evaluate potential bridge symptoms, which were defined as those that may influence the development of emotional problems in later life.

The study population consisted of 932 girls whose guardians completed a social behavior questionnaire (SBQ) when the children were 6 years old (baseline), then again at ages 8 and 10 years. At the ages of 15 and 22 years, 780 of the participants were screened for mental health disorders.

Of those who were screened, 270 (35%) had developed at least one anxiety disorder, and 128 (16%) had been diagnosed with major depression or some other depressive disorder.

New Analytic Approach

Rouquette noted that network analysis is a new approach that has recently been proposed to investigate and conceptualize mental disorders in a completely different way.

"It implies no latent structure, and associations among symptoms are not conceptualized as passive consequences of an underlying disorder. Instead, these intersymptom associations are considered as links that lead to the emergence of mental illness," she said.

With network analysis, "symptoms are not perceived as manifestations of an underlying disorder but rather as distinct entities with inherent causal power that can influence each other, are possibly self-reinforcing, and that can be part of causal chains, including feedback loops, which can culminate in disorders," she added.

This technique was used to assess 33 items from the SBQ and how they related to anxiety disorders in later life.

The researchers identified five bridge symptoms as having a distinctive position in the network: irritability, blaming others, being disliked by others, crying frequently, and being solitary.

"Our results suggest that girls may present symptoms such as kicking, telling lies, and destroying things, but as long as the bridge symptoms such as 'not liked by other children' or 'irritable' are not activated, the risk of later developing anxiety disorders remains stable," Rouquette said.

The findings also suggest that those girls who were disobedient, irritable, and disliked by others experienced both the earliest and strongest association with anxiety disorders over time.

"More research is necessary to replicate our findings, but the network approach appears to provide a natural language for clinicians and patients to use when discussing symptoms and therapeutic options," said Rouquette.

"Future research should also investigate whether the bridge symptoms we identified are also key predictors of other mental disorders," she added.

Symptoms "Reinforce Each Other"

Commenting on the findings for Medscape Medical News, Mary Morrison, MD, vice chair for research and psychiatry professor in the Department of Psychiatry and Behavioral Science at Temple University's Lewis Katz School of Medicine, Philadelphia, Pennsylvania, said that the study methods were "very good" and that the conclusions made sense.

"The idea of network structure is unfamiliar to most psychiatrists, and the authors do a good job explaining it and...that the symptoms in childhood can reinforce each other, potentially resulting in disorders later on," said Morrison, who was not involved in the study.

She added that the network analysis perspective may provide better understanding of which areas of the brain communicate with each other and their relative importance "if we can link these networks with the underlying brain connections and areas."

She noted that the study was limited by the challenges of identifying anxiety disorders during follow-up, by the small study population that excluded boys, and by the number of statistical tests that were carried out.

However, "it makes sense to look at girls separately from boys. As the authors point out, the epidemiology of these disorders is different in men and women, and the network structure may be different," she explained.

As for the findings, Morrison said that irritability seems to be an expression of an affective symptom in childhood. "So if the disruptive symptoms don't involve irritability or not being liked by other children, rejection, they don't influence the risk of anxiety disorders," she said.

"Disruptive behavior can have lots of reasons," and some of these symptoms are normal behaviors in childhood, she added.

Morrison also noted that in the study population, there was a high prevalence of anxiety disorders and depressive disorders for a community-based cohort compared with similar cohorts.

In addition, "both genetic predisposition and environment, particularly adverse childhood events like abuse and neglect, can contribute to these symptoms in childhood," she said.

The study was funded by a grant to Dr Rouquette from the OpenHealth Institute. The study authors have disclosed no relevant financial relationships.

JAMA Psychiatry. Published online August 15, 2018. Full text

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