- Email: [email protected]
Comorbidity and social phobia: evidence from epidemiologic and genetic studies
188
5:< Comorbidity and social phobia: evidence from epidemiologic and genetic studies
K.R. M e r i k a n g a s ~' and J. Angst b "Genetic Epidemiology Research Unil, Department ql Psychiatry, Yah' University School (?/ Medicine, New Haven, CT 06510, USA aml ~'PsJ,chmtru" " University Hospital Zurich. 8020 Zurich. Sn'itzerlaml K
Summary Prior to the last decade, social phobia has received scant attention in either adult or child psychiatry. Because social phobia was only detached from the broader category of phobic neurosis recently in the DSM-III, the validity of this condition as a discrete category has not been well established. Moreover, most of the systematic research on this syndrome has involved studies of treatment efficacy. The goals of this paper are: (1) to summarize the data oil the frequency, clinical features and the course of social phobia; (2) to describe the patterns of transmission of social phobia and its precursor, phobic neurosis in family and twin studies; and (3) to investigate the mechanisms for comorbidity of social phobia with alcoholism and affective disorders through the application of family study and longitudinal data.
Epidemiological studies The results of recent epidemiological studies yield an aggregate lifetime prevalence of social phobia of 2.6'/,,. In contrast to the other anxiety disorders, the sex ratio is approximately equal. The key features of this condition rarely remit with increasing age. Despite the chronicity, associated subjective distress, and pervasive interference with functioning, only a small proportion of affected persons seek professional treatment for this condition (Schneier et al., 1992).
Comorbidity and social phobia Recent epidemiological studies at the international level consistently reveal a high prevalence of comorbid disorders among community subjects with social phobia, with an average of 75-80% of social phobics meeting lifetime diagnostic criteria for another major condition. Likewise, the other anxiety states, including panic and generalized anxiety disorder, are significantly associated with social phobia in community samples. Finally, the co-occurrence of alcoholism and social phobia has consistently been noted in both males and females from community surveys. Despite the clear phenomenologic distinction between social phobia and the other subtypes of anxiety disorders, the majority of persons with social phobia also manifest sufficient affective symptoms to meet criteria for major depression or another affective disorder.
Family and twin studies Family history studies of phobic disorders have revealed that phobias in general tend to aggregate in families. Moreover, two recent studies have demonstrated specificity of transmission of the subtypes of phobia. That is, agoraphobia tends to cluster in the families of agoraphobic, but not simple or social phobic probands. Likewise, the relatives of simple phobics or social phobics tend to manifest the same subtype of phobia as that expressed by the index phobic proband. The findings of the only family study of social phobia which incorporated direct interviews of relatives revealed that there was a 3-fold greater risk of social phobia among the relatives of social phobics than among those of controls (Fyer et al., 1993). The results of twin studies suggest that a substantial proportion of the transmissibility of phobic disorders can be attributed to genetic factors. In a large-scale study of a systematic community based study of female twins, Kendler et al. (1992) found that although the majority of the variance in its etiology could be attributed to the unique environmental experience of the affected person, approximately 30% of the variance in the etiology of social phobia was under genetic influence.
Longitudinal association between social phobia and psychiatric disorders Similar to the findings from other epidemiological studies, social phobia was highly comorbid with other anxiety disorders, affective disorders, and alcoholism in the Zurich Cohort Study, a longitudinal prospective study of a community based sample of 591 young adults (Angst et al., 1990). The subjects, who were aged 19 20 at the initiation of the study, were interviewed
189 four times with a semi-structured clinical interview over an 1 l-year period, which enabled assessment of the order of onset of the other disorders with respect to the onset of social phobic symptoms. The most typical pattern of onset of these conditions among persons with all three disorders was the onset of social phobia followed by depression, and later by the onset of alcoholism. This paper will investigate these trends for comorbidity of other anxiety disorders and social phobia as well. Family studies of co-transmission of social phobia and other psychiatric disorders
Social phobia is strongly associated with affective disorders in family studies of patients with anxiety disorders and patients with depression as well. However, previous family studies were not designed to investigate the patterns of co-transmission of these conditions in order to discriminate between possible mechanisms for the associations between these disorders (Merikangas et al., 1993). In this paper, we also apply data from the Yale Family Study of Substance Abuse and Anxiety to investigate the co-segregation of anxiety disorders, alcoholism and affective disorders in families. This study is comprised of direct clinical assessments of the spouses and first-degree relatives of 212 probands with anxiety disorders, alcoholism, both disorders and unaffected controls, who were selected from treatment settings and from the general community. The preliminary results suggest that there are shared underlying etiologic factors which lead to the development of all three disorders, either alone or in combination. Possible mechanisms for these findings will be further explicated in this paper. Conclusion
When taken together, the prospective epidemiological and family study designs comprise a powerful method to investigate the mechanisms for comorbidity, including the source of the associations as well as their temporal relationship. Application of this hybrid study design in the present investigation revealed that: (1) social phobia, alcoholism and affective disorders are strongly associated in the general community and in families of probands with these disorders: (2) phobias and panic/generalized anxiety disorder have different patterns of association with alcoholism; and (3) the onset of social and simple phobia generally precedes that of alcoholism and depression, thereby suggesting that these conditions may comprise vulnerability factors for the development of alcohol problems. Future assessments of the longitudinal cohort, as well as the offspring of the probands in the family study, will provide valuable information in elucidating the mechanisms for the long-term course of these conditions. References
Angst, J., Vollrath, M., Merikangas, K.R. and Ernst, C. (1990) Comorbidity of anxiety and depression in the Zurich cohort study of young adults. In: Comorbidity of Mood and Anxiety Disorders, Maser, J.D. and Cloninger, C.R. (Eds.), pp. 123 138. American Psychiatric Press, Washington, DC. Fyer, A.J., Mannuza, A.S., Chapman, T.F., Liebowitz, M.R. and Klein, D.F. (1993) A direct interview study of social phobia. Arch. Gen. Psychiatry 50, 286-293. Kendler, K.S., Neale, M.C., Kessler, R.C., Heath, A.C. and Eaves, L.J. (1992) The genetic epidemiology of phobias in women. Arch. Gen. Psychiatry 49, 273 281. Merikangas, K.R., Weissman, M.M. and Risch, N.R. (1993) Comorbidity and co-transmission of alcoholism, anxiety and depression. Psychol. Med. (in press). Schneier, F.R., Johnson, J., Hornig, C.D., Liebowitz, M.R. and Weissman, M.M. (1992) Social phobia. Arch. Gen. Psychiatry 49, 282-288.
5:< Comorbidity and social phobia: evidence from epidemiologic and genetic studies
K.R. M e r i k a n g a s ~' and J. Angst b "Genetic Epidemiology Research Unil, Department ql Psychiatry, Yah' University School (?/ Medicine, New Haven, CT 06510, USA aml ~'PsJ,chmtru" " University Hospital Zurich. 8020 Zurich. Sn'itzerlaml K
Summary Prior to the last decade, social phobia has received scant attention in either adult or child psychiatry. Because social phobia was only detached from the broader category of phobic neurosis recently in the DSM-III, the validity of this condition as a discrete category has not been well established. Moreover, most of the systematic research on this syndrome has involved studies of treatment efficacy. The goals of this paper are: (1) to summarize the data oil the frequency, clinical features and the course of social phobia; (2) to describe the patterns of transmission of social phobia and its precursor, phobic neurosis in family and twin studies; and (3) to investigate the mechanisms for comorbidity of social phobia with alcoholism and affective disorders through the application of family study and longitudinal data.
Epidemiological studies The results of recent epidemiological studies yield an aggregate lifetime prevalence of social phobia of 2.6'/,,. In contrast to the other anxiety disorders, the sex ratio is approximately equal. The key features of this condition rarely remit with increasing age. Despite the chronicity, associated subjective distress, and pervasive interference with functioning, only a small proportion of affected persons seek professional treatment for this condition (Schneier et al., 1992).
Comorbidity and social phobia Recent epidemiological studies at the international level consistently reveal a high prevalence of comorbid disorders among community subjects with social phobia, with an average of 75-80% of social phobics meeting lifetime diagnostic criteria for another major condition. Likewise, the other anxiety states, including panic and generalized anxiety disorder, are significantly associated with social phobia in community samples. Finally, the co-occurrence of alcoholism and social phobia has consistently been noted in both males and females from community surveys. Despite the clear phenomenologic distinction between social phobia and the other subtypes of anxiety disorders, the majority of persons with social phobia also manifest sufficient affective symptoms to meet criteria for major depression or another affective disorder.
Family and twin studies Family history studies of phobic disorders have revealed that phobias in general tend to aggregate in families. Moreover, two recent studies have demonstrated specificity of transmission of the subtypes of phobia. That is, agoraphobia tends to cluster in the families of agoraphobic, but not simple or social phobic probands. Likewise, the relatives of simple phobics or social phobics tend to manifest the same subtype of phobia as that expressed by the index phobic proband. The findings of the only family study of social phobia which incorporated direct interviews of relatives revealed that there was a 3-fold greater risk of social phobia among the relatives of social phobics than among those of controls (Fyer et al., 1993). The results of twin studies suggest that a substantial proportion of the transmissibility of phobic disorders can be attributed to genetic factors. In a large-scale study of a systematic community based study of female twins, Kendler et al. (1992) found that although the majority of the variance in its etiology could be attributed to the unique environmental experience of the affected person, approximately 30% of the variance in the etiology of social phobia was under genetic influence.
Longitudinal association between social phobia and psychiatric disorders Similar to the findings from other epidemiological studies, social phobia was highly comorbid with other anxiety disorders, affective disorders, and alcoholism in the Zurich Cohort Study, a longitudinal prospective study of a community based sample of 591 young adults (Angst et al., 1990). The subjects, who were aged 19 20 at the initiation of the study, were interviewed
189 four times with a semi-structured clinical interview over an 1 l-year period, which enabled assessment of the order of onset of the other disorders with respect to the onset of social phobic symptoms. The most typical pattern of onset of these conditions among persons with all three disorders was the onset of social phobia followed by depression, and later by the onset of alcoholism. This paper will investigate these trends for comorbidity of other anxiety disorders and social phobia as well. Family studies of co-transmission of social phobia and other psychiatric disorders
Social phobia is strongly associated with affective disorders in family studies of patients with anxiety disorders and patients with depression as well. However, previous family studies were not designed to investigate the patterns of co-transmission of these conditions in order to discriminate between possible mechanisms for the associations between these disorders (Merikangas et al., 1993). In this paper, we also apply data from the Yale Family Study of Substance Abuse and Anxiety to investigate the co-segregation of anxiety disorders, alcoholism and affective disorders in families. This study is comprised of direct clinical assessments of the spouses and first-degree relatives of 212 probands with anxiety disorders, alcoholism, both disorders and unaffected controls, who were selected from treatment settings and from the general community. The preliminary results suggest that there are shared underlying etiologic factors which lead to the development of all three disorders, either alone or in combination. Possible mechanisms for these findings will be further explicated in this paper. Conclusion
When taken together, the prospective epidemiological and family study designs comprise a powerful method to investigate the mechanisms for comorbidity, including the source of the associations as well as their temporal relationship. Application of this hybrid study design in the present investigation revealed that: (1) social phobia, alcoholism and affective disorders are strongly associated in the general community and in families of probands with these disorders: (2) phobias and panic/generalized anxiety disorder have different patterns of association with alcoholism; and (3) the onset of social and simple phobia generally precedes that of alcoholism and depression, thereby suggesting that these conditions may comprise vulnerability factors for the development of alcohol problems. Future assessments of the longitudinal cohort, as well as the offspring of the probands in the family study, will provide valuable information in elucidating the mechanisms for the long-term course of these conditions. References
Angst, J., Vollrath, M., Merikangas, K.R. and Ernst, C. (1990) Comorbidity of anxiety and depression in the Zurich cohort study of young adults. In: Comorbidity of Mood and Anxiety Disorders, Maser, J.D. and Cloninger, C.R. (Eds.), pp. 123 138. American Psychiatric Press, Washington, DC. Fyer, A.J., Mannuza, A.S., Chapman, T.F., Liebowitz, M.R. and Klein, D.F. (1993) A direct interview study of social phobia. Arch. Gen. Psychiatry 50, 286-293. Kendler, K.S., Neale, M.C., Kessler, R.C., Heath, A.C. and Eaves, L.J. (1992) The genetic epidemiology of phobias in women. Arch. Gen. Psychiatry 49, 273 281. Merikangas, K.R., Weissman, M.M. and Risch, N.R. (1993) Comorbidity and co-transmission of alcoholism, anxiety and depression. Psychol. Med. (in press). Schneier, F.R., Johnson, J., Hornig, C.D., Liebowitz, M.R. and Weissman, M.M. (1992) Social phobia. Arch. Gen. Psychiatry 49, 282-288.