The structure and stability of common mental disorders - The NEMESIS Study

Background: We analyzed the underlying latent structure of 12-month DSM-III -R diagnoses of 9 common disorders for the general population in the Nether lands. In addition, we sought to establish (1) the stability of the latent structure underlying mental disorders across a 1-year period (structural st ability) and (2) the stability of individual differences in mental disorder s at the level of the latent dimensions (differential stability). Methods: Data were obtained from the first and second measurement of the Ne therlands Mental Health Survey and Incidence Study (NEMESIS) (response rate at baseline: 69.7%, n=7076; 1 year later, 79.4%, n=5618). Nine common DSM- III-R diagnoses were assessed twice with the Composite International Diagno stic Interview with a time lapse of 1 year. Using structural equation model ing, the number of latent dimensions underlying these diagnoses was determi ned, and the structural and differential stability were assessed. Results: A 3-dimensional model was established as having the best fit: a fi rst dimension underlying substance use disorders (alcohol dependence, drug dependence); a second dimension for mood disorders (major depression, dysth ymia), including generalized anxiety disorder; and a third dimension underl ying anxiety disorders (simple phobia, social phobia, agoraphobia, and pani c disorder). The structural stability of this model during a 1-year period was substantial, and the differential stability of the 3 latent dimensions was considerable. Conclusions: Our results confirm the 3-dimensional model for 12-month preva lence of mental disorders. Results underline the argument for focusing on c ore psychopathological processes rather than on their manifestation as dist inguished disorders in future population studies on common mental disorders .