VIENNA – Social anxiety disorder, regardless of age of onset, is consistently associated with strongly increased risk for subsequent depression, according to 10-year results of the large prospective Early Developmental Stages of Psychopathology Study.
This conclusion is an about-face from an earlier report from the EDSP based on only 4 years of longitudinal follow-up. That report found that social anxiety disorder (SAD) was related to an increased risk of later depression only among individuals aged 18–24 years at SAD onset (Arch. Gen. Psychiatry 2001;58:251–6).
It is now quite clear from the 10-year data that the earlier finding was attributable to insufficient follow-up; those with SAD onset before the age of 18 years had not yet been followed long enough to enter the prime period for onset of depression, Katja Beesdo, Ph.D., said at the annual congress of the European College of Neuropsychopharmacology.
EDSP enrolled 3,021 Munich youths at age 14–24 years and followed them prospectively for an average of 10 years. The cumulative incidence of SAD was 11%, based on the DSM-IV Munich-Composite International Diagnostic Interview, while the cumulative incidence of depression was 27%.
SAD proved to be a predominantly adolescent-onset disorder, with few cases beginning before age 10 years by self-report or after age 19 years. This underscored the notion that adolescence is the most vulnerable period for the onset of SAD, and would be the logical focus of early intervention efforts aimed at reducing its burden and preventing secondary depression, according to Dr. Beesdo, a clinical psychologist at Technical University, Dresden, Germany.
Roughly 60% of the subjects with SAD were diagnosed with comorbid depression during the study period. In most cases, SAD was diagnosed first. Depression displayed a far different incidence pattern, with onset remaining consistently high throughout subjects' later 20s and early 30s.
Participants with prior SAD were at twofold greater risk of developing depression than those without prior SAD. In a multivariate analysis, two significant factors differentiated the 60% of SAD patients who went on to meet criteria for depression from the 40% who did not: comorbid panic attacks and a more malignant course of SAD, as reflected in relatively high behavioral inhibition.
In an interview, Dr. Beesdo said other psychiatric disorders that clustered with SAD in the EDSP study were alcohol and substance abuse disorders and, to a lesser extent, pain and other somatoform disorders. Surprisingly, SAD was not associated with eating disorders, she noted. “But we had only a few cases of eating disorders, so I don't know how reliable that finding is,” Dr. Beesdo added.
“Because the other way around, patients with eating disorders are often social phobic.”
The German Federal Ministry of Education and Research funded the EDSP study.