Familial transmission of simple phobias and fears. A preliminary report.

Preliminary data from a blind direct interview family study indicate a significantly higher risk for simple phobia among first-degree relatives (n = 49) of simple phobic probands (who had no other anxiety disorder) as compared with first-degree relatives (n = 119) of never mentally ill controls (31% vs 11%, relative risk = 3.3). Female relatives were more likely to be affected than male relatives (48% vs 13%), though this difference did not reach conventional significance in an age-corrected analysis. Significant between-group differences were not found in risks for (1) other anxiety, affective, and substance abuse disorders, and (2) simple irrational fears that did not meet disorder criteria. The results suggest that simple phobia is a highly familial disorder that does not transmit increased risk for other phobic or anxiety disorders. The specificity of increased risk among the relatives of simple phobics is consistent with the distinction between simple phobia, social phobia, and agoraphobia. However, complete delineation of the transmissional relationship between these illnesses requires assessment of the extent to which risk for simple phobia can be transmitted by individuals with other phobic or anxiety disorders. Replication of these preliminary findings in larger clinically and epidemiologically selected samples is needed.