Comparing primary and secondary generalized anxiety disorder in a long-term naturalistic study of anxiety disorders

This study explores the potential differences in comorbidity and course bet ween primary generalized anxiety disorder (GAD), which develops before othe r anxiety disorders, and secondary GAD. As part of the Harvard/Brown Anxiet y Research Project (HARP), a naturalistic, long-term, longitudinal study of 711 subjects from a variety of clinic settings with DSM III-R defined anxi ety disorders, 210 subjects with GAD were identified. Of these, 78 (37%) ha d primary GAD, and 84 (40%) had secondary GAD; of the remainder, 28 (13%) h ad no other anxiety disorder and 20 (10%) developed GAD within a month of a nother anxiety disorder and were excluded from the analysis. All subjects w ere comorbid for at least one other anxiety disorder. Primary GAD subjects were more likely to be in episode at intake (90% vs. 77%, P = .04) and less likely than secondary GAD subjects to have current or past agoraphobia wit hout panic disorder (3% vs. 11%, P = .04), social phobia (19% vs. 52%, P = .001), simple phobia (14% vs. 30%, P = .02), or post traumatic stress disor der (5% vs. 20%, P = .01). Subjects with primary GAD were also less likely to have current or past alcohol use disorders (17% vs. 37%, P = .004) or ma jor depressive disorder (60% vs. 76%, P = .03). There were no significant d ifferences in either treatment approaches of remission rates for primary co mpared to secondary GAD. Whether GAD first occurs before or after another a nxiety disorder, it is similar in terms of prevalence, treatment, and cours e. The only significant differences between primary and secondary GAD lie i n the rates of comorbidity of both other anxiety disorders and non-anxiety disorders, including major depression and substance abuse. These results su pport the concept of GAD as a valid, separate and distinct entity, whether it occurs primarily or secondarily. (C) 1999 Wiley-Liss, Inc.