The main finding of this study was that BDI-II somatic symptom scores were only minimally higher for female versus male psychiatry outpatients with MDD matched on cognitive/affective symptom scores. Women scored just over a point higher than men, accounting for only 4% of their total BDI-II scores. Furthermore, based on BDI-II somatic symptoms item scores, only 7% of women versus 5% of men and were classified as having “somatic depression.”
These results, numerically, are consistent with results from two prominent earlier studies that reported that “somatic depression” was twice as prevalent among women with MDD compared to men with MDD 
. In those two studies, rates of “somatic depression” were 8% and 3% for women versus 4% and 1.5% for men, respectively. In both of those studies, and in the present study, however, more than 90% of men and women with MDD were not classified as having “somatic depression.”
The key difference between the present study and the two earlier studies by Silverstein 
is that the previous studies focused on relative risk without interpreting the meaningfulness of findings in terms of absolute risk. In the context of very low rates, however, communication of relative risk is often highly misleading 
. For instance, increasing risk from 1 in 10,000 to 2 in 10,000 would technically be “double the relative risk,” but, in most cases, would not be clinically meaningful. Silverstein suggested that the increased relative risk of “somatic depression” for women was a possible explanation for gender differences in depression rates and severity, but only a very small percentage of MDD patients were classified as having “somatic depression,” which was also the case in the current study. Thus, the very minor differences between rates of “somatic depression” for men and women in all of these studies, along with the minimal gender difference in BDI-II somatic symptom scores in the present study, suggest that gender differences in depression are not adequately explained in terms of somatic symptoms.
A number of other studies have examined whether there are gender differences in the endorsement of depressive symptoms on an item-by-item basis 
. Some studies have found that women are more likely to report certain somatic items, including appetite disturbances, weight disturbances and fatigue than men 
. However, the specific somatic symptoms identified as potentially different for men and women are not the same across studies, and most somatic symptom items analyzed show no differences. On the other hand, some studies have reported that women are more likely than men to report certain cognitive/affective items, such as tearfulness, feelings of guilt, feelings of worthlessness, sexual disinterest and thoughts of death, than men 
. However, as with somatic symptoms, consistent patterns do not emerge across studies and, for most cognitive/affective symptoms examined, there are no differences. Possible reasons that have been suggested to explain these findings include the use of different methods to assess symptoms of depression and different patients and settings 
. In addition, all of these studies conducted statistical tests on many different items, without adjustment for multiple comparisons, and based their conclusions of gender differences on differences in small numbers of items among many tested. Given this, the inconsistent findings would be consistent with very minimal differences overall, as we found in the present study. In the present study, although we presented item-by-item data, our hypothesis was tested based on a single comparison of differences in overall somatic symptom scores.
There is no debating that women have higher rates of depression and report more severe depressive symptoms than men, and it is important to better understand how and why these gender differences in depression occur in order to create more efficacious treatments. The findings of this study, however, do not support the existence of a somatic subtype of depression among women that may explain gender differences in depression. Given this finding, other explanations that have been advanced may be more promising. For instance, it has been suggested that gender differences in depression may be related to 1) prior anxiety, which is more common among women than men 
, 2) the willingness of women to admit their depression more than men 
, 3) the tendency for women to ruminate about problems more than men 
, 4) higher levels of stress and lower levels of fulfillment associated with traditional male versus female sex roles 
, and 5) hormonal changes during puberty 
One limitation of this study is that we studied a sample of adults with MDD who sought treatment at one of two clinics in New Jersey or Pennsylvania, USA, which could limit the generalizability of results. On the other hand, the results of the study are generally similar to Silverstein's 
previous findings using larger, more representative samples of patients, and robustly demonstrate that somatic symptom reporting is not likely an explanation for gender differences. A second limitation of this study is that, as in Silverstein's studies 
, our definition of “somatic depression” was arbitrary. However, the amount of men and women with “somatic depression” in this study was similar to that in Silverstein's studies 
and facilitated comparisons. Also, since different assessment methods were used, the definitions of “somatic depression” were somewhat different. We used a definition that was based on published factor analyses of the BDI-II, which may differ somewhat from other conceptualizations. A third limitation of this study is that we did not have information regarding whether or not patients were diagnosed with additional psychiatric diagnoses besides MDD and therefore, it is possible that this sample may not be representative of patients only with MDD. Lastly, other possible limitations of the study were that MDD diagnoses were not based on a structured clinical interview and that depressive symptoms were assessed using the BDI-II, which is not a diagnostic tool. The BDI-II, however, does contain the core symptoms that are covered in the DSM-IV. In addition, using the BDI-II allowed for an assessment of continuous symptom scores and overall contribution of somatic symptoms whereas a structured clinical interview only permits counting the presence or absence of symptoms.
In summary, it is well-known that women have a higher prevalence of MDD and report more severe depressive symptoms than men. The results of this study show that differences in the experience and reporting of somatic symptoms explain only a small portion of these gender differences. Future studies examining this issue should focus on additional explanations.