The Genetic Factors of Social Phobia
Social phobia, sometimes referred to as social anxiety disorder, is a persistent, unrealistically intense fear of social situations. These situations may involve the fear of being ridiculed or judged by others, or simply just being exposed to unfamiliar people. People with social phobia try to avoid situations in which they may be evaluated, show signs of anxiety or have to behave in a way in which they would find embarrassing. Sufferers can feel extreme anxiety in situations which produce at least slight nervousness in the general population, such as public speaking or performing in public, and they can also feel extreme anxiety in day to day situations that the general population are not bothered by, such as eating in public or using public toilets.
Social phobia generally develops in adolescence, however cases of social phobia are also found in children. There are two types of social phobia; specific and generalised. A diagnosis of one or the other of these types depends on the range of situations in which an individual feels anxiety in. Generalised social phobia is associated with an earlier age of onset, higher co-morbidity with other anxiety disorders and increased negative effects on a person’s social and occupational activities. Both specific and generalised social phobia tend to be chronic without treatment (Kring et al, 2007).
Genetic Factors of Social Phobia
In psychology all behaviour, including the exhibition of symptoms of mental illnesses, is subject to the nature or nurture debate. That is, is the behaviour due to genetic influence, environmental influence, or an interaction between both genetic and environmental factors?
A study by Kessler and colleagues in 1992 that looked at 2163 female twins reported a heritability rate (the degree to which genetic factors influence the development of the disorder) of 30-40% for all phobias. However, they pointed out that compared to simple phobias, social phobia appeared to arise from a moderately strong genetic influence combined with non-specific environmental influences.
In 2001, Hettema and colleagues conducted a meta analysis of four studies that had looked at genetic and environmental influence on several anxiety disorders. They found that all studies supported the familial aggregation of phobias. There was a significant association between phobias in subjects and their first degree relatives, such as parents, children or siblings, and they argue that the major source of familial risk is genetic rather than due to shared environment.
In fact, it is thought that someone with a first degree relative who suffers from an anxiety disorder is ten times more likely to develop an anxiety disorder themselves. They reported the same heritability rate (30-40%) as Kessler et al. However, this heritability rate is lower than that of other mental health disorders such as schizophrenia or bipolar disorder and is at best a moderate rate. This means that the majority of the liability should be explained by shared or unique environmental influences. However, the authors believe that the true heritability rate of anxiety disorders is underestimated, and believe it to be closer to 50-60%.
Another study by Hettema and colleagues in 2005 however revealed quite different results when looking at genetic factors of social phobia. In this study only a 10% heritability rate for social phobia was reported, whereas a rate of 25-35% was reported for all other anxiety disorders.
In conclusion, although all anxiety disorders, including social phobia, appear to have a strong familial aggregation, this may be due to shared environmental experiences as opposed to or in addition to genetic influences. Indeed, an interaction between genes and the environment is becoming the favoured view for explaining most mental illnesses.
Kring, A.M., Davison, G.C., Neale, J.M. & Johnson, S.L. (2007) Abnormal Psychology. USA: John Wiley & Sons.
Kessler, R.C., Kendler, K.S., Neale, M.C., Heath, A.C. & Eaves, L.J. (1992) The genetic epidemiology of phobias in women: the interrelationship of agoraphobia, social phobia, situational phobia and simple phobia. Archives of General Psychiatry, 49, (4), 273-281.
Hettema, J.M., Neale, M.C. & Kendler, K.S. (2001) A review and meta analysis of the genetic epidemiology of anxiety disorders. The American Journal of Psychiatry, 158, (10), 1568-1578.
Hettema, J.M., Prescott, C.A., Myers, J.M., Neale, M.C. & Kendler, K.S. (2005) The structure of genetic and environmental risk factors for anxiety disorders in men and women. Archives of General Psychiatry, 62, 182-189.