The structure of common psychiatric symptoms: how many dimensions of neurosis?

In order to replicate and elaborate the two-dimensional model of depression and anxiety underlying the structure of common psychiatric symptoms proposed by Goldberg et al. (1987), we carried out latent trait analyses on PSE symptom data of the original Manchester study and two recent Dutch studies. We used the same analytical strategy as Goldberg et al. to facilitate comparison with the earlier work. It was found that a more comprehensive set of common psychiatric symptoms caused an extra, third dimension to emerge, so that the earlier anxiety dimension became split between a specific anxiety axis characterized by situational and phobic anxiety and avoidance, and a non-specific anxiety axis characterized by free-floating anxiety, various symptoms relating to tension, irritability and restlessness. It is argued that three dimensions are sufficient to account for the covariance between common psychiatric symptoms. A fairly consistent correlation between the non-specific anxiety and the depression dimension was found across sites, as well as independence of the specific anxiety dimension from the other two dimensions. Furthermore, the depression dimension was robust with similar symptom profiles across samples, but there appeared to be local differences in the structure of anxiety symptoms.