Anxiety in situations involving potential evaluation by others (e.g. job interviews, public speaking engagements, first dates) falls within the realm of ‘normal’ social anxiety. For individuals with social anxiety disorder, however, situations such as these are typically associated with incapacitating levels of anxiety and a desire for escape or avoidance. Socially anxious individuals are often self-critical and perfectionistic and go to great lengths to avoid the negative evaluation of others that they may perceive as epidemic. Commonly, persons with social anxiety disorder experience somatic symptoms such as blushing, trembling, dry mouth, or perspiring, which they believe will be noticed by others and provide further evidence of their incompetence. Children may manifest their anxiety differently than adults; they may cry, throw tantrums, freeze, shrink from interactions with strangers, and they may not acknowledge that their fears are irrational.⁽⁶⁾ By leaving anxiety-provoking situations (escape) or foregoing them entirely (avoidance), individuals with social anxiety disorder may reduce or prevent the immediate experience of anxiety, but this behaviour reinforces beliefs in their inadequacies and serves to maintain anxiety in the absence of objective threat.^(7,8)

Individuals with social anxiety disorder experience significant impairment in social, educational, and occupational functioning.^(5,9) They are less likely to marry and are more likely to divorce than those without the disorder.⁽¹⁰⁾ They also have fewer friends and more trouble getting along with the friends they have than persons without the disorder.⁽¹¹⁾ Individuals with social anxiety disorder assessed in a primary care setting reported missing an average of 3 days of work and having an average of 6 days of reduced productivity in the last month because of their emotional problems.⁽¹²⁾ Comparatively, mentally healthy individuals reported less than 1 day of lost work and reduced productivity combined. Unemployment, underemployment (working at a level below the individual’s abilities), and financial dependency are also characteristic of individuals with social anxiety disorder.⁽¹⁰⁾

Genetic factors appear to contribute to the emergence of social anxiety disorder. Higher rates of social anxiety disorder have been found in relatives of individuals with the disorder compared to relatives of persons without the disorder.⁽³⁰⁾ Further, rates of social anxiety disorder in first-degree relatives of probands with the generalized subtype are higher than in relatives of probands with the non-generalized subtype or with no psychiatric history.⁽³¹⁾ Kendler et al.⁽³²⁾ report concordance rates for social anxiety disorder among monozygotic twins (24.4 per cent) to be greater than the rates for dizygotic twins (15.3 per cent). A study conducted with the same cohort 8 years later found the heritability of social anxiety disorder to be approximately 50 per cent in female twins⁽³³⁾ and 25 per cent in male twins.⁽³⁴⁾

Neurobiological factors may also be associated with social anxiety disorder. Imaging studies of individuals with social anxiety disorder have demonstrated increased activity in regions associated with fear and anxiety (i.e. prefrontal cortex, amygdala, hippocampus) during anxiety-provoking tasks.⁽³⁵⁾ Given the efficacy of serotonin reuptake inhibitors and monoamine oxidase inhibitors in treating social anxiety disorder,⁽³⁶⁾ dysregulation of the serotonin⁽³⁷⁾ and dopamine⁽³⁸⁾ systems have been investigated as potential correlates of the disorder.

Several studies also suggest the importance of parental influences and significant life events in the development of social anxiety disorder. Persons with social anxiety recall observing their mothers act more fearful and avoidant of social interactions⁽³⁹⁾ and describe their parents as overprotective.⁽⁴⁰⁾ Stressful social and performance situations early in life (e.g. public ridicule, being bullied, mind going blank during a presentation) are also commonly reported by persons with social anxiety disorder.⁽⁴¹⁾

Social anxiety disorder is chronic and unlikely to remit without treatment. The disorder persists throughout adulthood⁽⁴²⁾ and its course is unrelated to gender, age of onset, duration of illness, level of functioning at intake, lifetime history of anxiety disorders, or current comorbidity of anxiety or depressive disorders.^(42,43) Two conditions related to social anxiety disorder emerge in childhood and are relatively stable into adulthood—shyness and behavioural inhibition. Individuals who had been shy as children exhibited overall lower levels of functioning when assessed 30 years later.⁽⁴⁴⁾ Similarly, children described as behaviourally inhibited, or having the tendency to withdraw from novel people, settings, or objects, have demonstrated increased risk for the development of social anxiety disorder in adolescence.⁽⁴⁵⁾ Behavioural inhibition was also more prevalent in children of individuals with anxiety disorders and remained relatively stable for over 7 years in children initially assessed between the ages of 21 to 31 months.⁽⁴⁶⁾ These findings suggest that extreme shyness and behavioural inhibition may be early manifestations of social anxiety disorder.