Anxiety Disorders

Evidence for biological factors that predispose children to anxiety disorders is based largely on findings from family aggregation, twin, behavioral genetic, and behavioral inhibition studies. Family aggregation studies suggest that children whose parents have an anxiety disorder are at risk for developing an anxiety disorder themselves (Biederman et al. 2001). Similarly, parents whose children have an anxiety disorder are likely to show anxiety disorders or symptoms themselves. Research on family aggregation also suggests that when parents have an anxiety disorder, mothers are more often associated with familial transmission of anxiety than fathers. Also, children of anxious parents are likely to have an earlier onset for anxiety disorders than their parents.

Twin studies also suggest a familial transmission. For example, concordance rates from different monozygotic (identical) and dizygotic (fraternal) twin pairs suggest a strong genetic basis for anxiety neurosis. Thalia C. Eley's (1999) review of behavioral genetic research concluded that factors in shared and nonshared environments of parents with anxiety disorders have an important influence on the development and maintenance of most anxiety disorders in their children and adolescents.

Recent research on behavioral inhibition and anxiety has provided important neurobiological insights regarding correlates in the etiology of anxiety disorders (Sallee and Greenawald 1995). Behavioral inhibition refers to the temperamental style of approximately 10 to 15 percent of Euro-American infants who are predisposed to being irritable, shy, and fearful as toddlers, and cautious, quiet, and introverted as school-aged children (e.g., Kagan 1989).

Although family, twin, behavioral genetic, and behavioral inhibition investigations all provide empirical support for biological dispositional factors in the etiology of anxiety disorders in children, the specific mechanism of transmission are unclear. This represents a critical area for further research.