Genetic Influences on Anxiety in Children: What we’ve Learned and Where we’re Heading

Abstract

Anxiety is a common problem, typically beginning early in life. This article explores reasons for individual differences in levels of anxiety among children, by reviewing the genetic literature. The plethora of research to date has demonstrated clearly that both genes and environmental influences play important roles in explaining differences in levels of anxiety of various types among children. This has encouraged researchers to search for specific genes and environmental influences upon anxiety. Despite important progress in identifying links between anxiety and specific genes-including associations between serotonin and dopamine genes and different symptoms of anxiety-overall, progress has been slow because multiple genes of small effect size are likely to influence anxiety. This article explains how the hunt for genes involved in anxiety is likely to benefit from genetically sensitive research, which examines the co-occurrence of symptoms; includes measures of the environment; and examines endophenotypes and risk pathways. KEY WORDS: anxiety; children; environment; genes; twins IntroductionAnxiety is characterized by fear, concern or dread. This may be related to a specific event or situation that is perceived threatening, or may be more pervasive. Individuals with high levels of anxiety may meet criteria for an anxiety disorder, of which there are many types (Diagnostic and Statistical Manual of Mental Disorders-IV, American Psychiatric Association, 1994). Although anxiety is a common difficulty occurring throughout the life-course it typically begins early in life Kessler, Berglund, Demler, Jin, & Walters, 2005), which suggests that research examining the origins of anxiety may be beneficial in childhood. While most children show at least some symptoms of anxiety, the exact prevalence of anxiety disorders is debatable. For example, a review of epidemiological studies examining rates of anxiety disorders in preadolescent children reported prevalence rates between 2.6 and 41.2% (Cartwright-Hatton, McNicol, & Doubleday, 2006).Given the widespread nature of childhood anxiety, researchers are trying to understand more about why anxiety develops and persists. One research area of rapid growth in this respect is genetics and this type of research has tended to focus upon symptoms of anxiety within the full range as opposed to anxiety disorders. A sceptic may point out that we are stuck with the genes that we are born with and argue that therefore, understanding the way in which genes influence behavior is of little use. However, as will be discussed in the course of this article, it is becoming increasingly clear that although it is true that our genes do not change throughout development, genes may become more or less influential over time; and the environment can influence the way in which our genes impact upon our emotions and behaviors. This article will document the progress that has been made in understanding genetic and environmental influences on childhood anxiety. Although there are numerous reviews of ...

Pediatric anxiety disorders: from neuroscience to evidence-based clinical practice

“…Family studies have shown that anxiety disorders are familial, 47,48 whereas twin studies demonstrated that anxiety disorders are heritable 49 and that the proportion of the phenotypic variability explained by genetic factors (heritability) for anxiety disorders ranges from 25-60%. [49][50][51][52] In general, this represents modest heritability for a psychiatric condition, clearly meaningful but lower than for highly heritable conditions, such as attention deficit hyperactivity disorder (ADHD) or autism.…”

“…It is only through effects on the brain that genes and the environment can ultimately result in emotional and behavioral abnormalities. 48 Candidate gene studies search for specific loci at the genome. While these have been criticized as being vulnerable to type I errors, they have identified several risk genes for anxiety disorders 55 ; however, consistent with type I errors, a recent review suggested that available work resulted in ''not a single instance of replication.''…”

“…189 This is a general overview about pediatric anxiety disorders. More specific and comprehensive reviews about the following topics can be found in the literature: prevalence, 15,[18][19][20] behavioral inhibition, [190][191][192] behavioral genetics, 48,52 genetics, 55,56,193,194 gene vs. environment interplay, 52,70 pathophysiology, 31,71 neural substrates, 71 normal development of fears, 195 psychopharmacological treatment, [196][197][198] and CBT. 164,[199][200][201] Conclusions Anxiety disorders are prevalent, associated with a number of negative life outcomes, and currently underrecognized and under-treated.…”

The Relationship between Parenting and Internalizing Problems in Childhood

“…Twin studies [19][20][21][22][23] have suggested that additional genetic efects account for a small portion of variance in children's trait anxiety and depression compared to non-shared environment (i.e. non-parenting factors).…”

A culturally-sensitive model of the development of child anxiety.

“…More specifically, results showed that genetic factors shared by the twins explained 58% to 99% of the co-variance in the anxiety disorders under examination, leading the authors to conclude that the role of genetic factors in the etiology of co-occurring anxiety disorders is quite significant, whereas non-shared environmental influences appear to be less salient. Although the role of shared environmental factors has not been supported in studies of adults (Hettema et al, 2001), there is support for the role of both unique and shared environmental influences in the etiology of anxiety during childhood (Gregory & Eley, 2007;Vasey and Dadds, 2001). …”