Background: Panic disorder and major depression (MDD) are both highly familial disorders that co-occur in individuals but do not cosegregate in families. Evidence concerning their familial aggregation with other psychiatric disorders, including phobias, substance abuse, and antisocial personality, has been contradictory. In part, the contradictory findings may be due to failure to account for the effects of proband comorbidity on risks in relatives.
Methods: A family study of 1047 adult first-degree relatives of 193 probands in four diagnostic groups (panic disorder without MDD, panic disorder plus MDD, early-onset MDD, and screened normal controls) was used to determine the range of psychiatric disorders associated with panic disorder and MDD and the effects of proband comorbidity on the rates of disorders in relatives.
Results: Compared to relatives of normal controls, relatives of probands with panic disorder or panic disorder and MDD showed significantly increased risks of panic disorder, but relatives of probands with early-onset MDD did not. After proband comorbidity was controlled for, relatives of probands with panic disorder were also at a significantly increased risk for social phobia but not for any other psychiatric disorders. Relatives of probands with early-onset MDD were at significantly increased risk for MDD, dysthymia, abuse of or dependence on alcohol and other drugs, and antisocial personality disorders but not for any other psychiatric disorders.
Conclusions: We conclude that panic disorder is a specific familial entity that is not associated with a broad range of other anxiety or other psychiatric disorders, with the possible exception of social phobia. Dysthymia, substance abuse, and antisocial personality appear to be on the spectrum of early-onset MDD.