A multifactorial developmental model for the etiology of major depression in a population-based sample.

BACKGROUND: Kendler et al. proposed gender specific developmental models for Major Depression (MD) using a population-based sample of north-American adult twins. The aim of this study was to test whether any of the models could predict both MD and other depressive disorders among unrelated Swedes of both sexes. To test depression specific prediction the sample was overrepresented for other psychiatric diagnoses.
METHODS: Persons with and without psychiatric symptoms were randomly selected from a population-based questionnaire study and interviewed by psychiatrists. Diagnoses were made according to DSM-IV. The study included 81 persons with MD, 132 persons with other depressive disorders, 136 persons with other psychiatric diagnoses and 744 persons without diagnosis. Path and correlation analyses were performed using 16 risk factors.
RESULTS: The path analysis revealed similar prediction values of MD for the female and male models, i.e. two-thirds of the variance in liability to MD and depression in general when controls consisted of persons without psychiatric diagnosis. Prediction of depression was only slightly weakened when distinguishing cases from those with other psychiatric diagnoses. The risk factors with the strongest unique influence on depression were from early adolescence: neuroticism, low self-esteem, anxiety; from late adolescence: trauma; and history of depression. LIMITATIONS: Possibly some limited recall bias.
CONCLUSIONS: The model was successfully replicated in both genders of unrelated Swedes. In addition, the model highly predicted other subtypes of depression, despite that the sample was overrepresented for other psychiatric diagnoses. The results support similar etiology of MD and other depressive disorders.