A family study of co-morbidity between generalized social phobia and generalized anxiety disorder in a non-clinic sample.
BACKGROUND
High rates of co-morbidity between Generalized Social Phobia (GSP) and Generalized Anxiety Disorder (GAD) have been documented. The reason for this is unclear. Family studies are one means of clarifying the nature of co-morbidity between two disorders.


METHODS
Six models of co-morbidity between GSP and GAD were investigated in a family aggregation study of 403 first-degree relatives of non-clinical probands: 37 with GSP, 22 with GAD, 15 with co-morbid GSP/GAD, and 41 controls with no history of GSP or GAD. Psychiatric data were collected for probands and relatives. Mixed methods (direct and family history interviews) were utilised.


RESULTS
Primary contrasts (against controls) found an increased rate of pure GSP in the relatives of both GSP probands and co-morbid GSP/GAD probands, and found relatives of co-morbid GSP/GAD probands to have an increased rate of both pure GAD and co-morbid GSP/GAD. Secondary contrasts found (i) increased GSP in the relatives of GSP only probands compared to the relatives of GAD only probands; and (ii) increased GAD in the relatives of co-morbid GSP/GAD probands compared to the relatives of GSP only probands.


CONCLUSIONS
The study did not directly interview all relatives, although the reliability of family history data was assessed. The study was based on an all-female proband sample. The implications of both these limitations are discussed.


CONCLUSIONS
The results were most consistent with a co-morbidity model indicating independent familial transmission of GSP and GAD. This has clinical implications for the treatment of patients with both disorders.
Coelho
Helen F
HF
Winnicott Research Unit, School of Psychology, University of Reading, 3 Earley Gate, Whiteknights, Reading, UK RG6 6AL.
Cooper
Peter J
PJ
Murray
Lynne
L
D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D015897:Comorbidity; D003710:Demography; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D010698:Phobic Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D011247:Pregnancy; D015995:Prevalence; D011446:Prospective Studies