a1 Department of Psychology, Stony Brook University, Stony Brook, NY, USA
a2 Oregon Research Institute, Eugene, OR, USA
Background Depression and anxiety are highly co-morbid disorders. Two latent trait models have been proposed to explain the nature of the relationship between these disorders. The first posits that depressive and anxiety disorders are both manifestations of a single internalizing factor. The second model, based on a tripartite model proposed by Clark & Watson [Journal of Abnormal Psychology (1991) 100, 316–336], proposes that depressive and anxiety disorders reflect a combination of shared and disorder-specific factors.
Method We directly compared the two models in a sample of 891 individuals from the Oregon Adolescent Depression Project who participated in up to four diagnostic assessments over approximately 15 years. Structural equation models were used to examine the relationship between depressive and anxiety disorders across different developmental periods (<14, 14–18, 19–23, 24–30 years of age).
Results The one- and three-factor models were hierarchically related. Thus, a direct comparison between the one- and three-factor models was possible using a χ2 difference test. The result found that the three-factor model fit the data better than the one-factor model.
Conclusions The three-factor model, positing that depressive and anxiety disorders were caused by a combination of shared and disorder-specific factors, provided a significantly better fit to the data than the one-factor model postulating that a single factor influences the development of both depressive and anxiety disorders.
(Received February 28 2007)
(Revised June 05 2007)
(Accepted June 11 2007)
(Online publication September 06 2007)
Portions of these findings were presented at the Virtual Meeting of the Society for Research in Psychopathology, October 2005. The actual meeting was cancelled due to hurricanes.