A variety of studies suggest the existence of a distinct phenotype of somatic depression, i.e., depression accompanied by significant somatic symptomatology. Previous research suggests that the gender difference in the prevalence of depression is primarily due to a difference in somatic depression. The aim of this study was to compare the gender difference in the prevalence of somatic depression and of depression not accompanied by significant somatic symptomatology (labelled "pure" depression) in two representative samples, the National Comorbidity Survey-Replication (NCS-R) and the Zurich Study.
The gender difference in lifetime somatic depression was compared to that of pure depression based on analyses weighted back to the general population in two representative samples. The NCS-R analyses involved a narrow definition of somatic depression with items from the DSM criteria for depression--appetite, sleep, and fatigue. The analysis of the Zurich study added headaches, body image issues, and breathing difficulties to the criteria and comparison to atypical depression.
In both samples, the gender difference in depressive prevalence was due to a large difference in somatic depression with other phenotypes showing little or no gender difference. The gender differences were found to be due to the somatic symptoms rather than the number of symptoms and were much larger for somatic than for atypical depression.
The gender difference in the prevalence of depression results from the higher prevalence among women of a specific phenotype, somatic depression.