Research reportGender differences in depressive symptoms: An artefact caused by measurement instruments?
Introduction
It is widely accepted as a fact that depression and depressive symptoms are more prevalent in women than in men (Weissman and Klerman, 1977, Weissman and Klerman, 1985, Weissman et al., 1991, Kessler et al., 1993). Several possible explanations for this gender difference have been suggested, e.g. greater exposure to life stress (Aneshensel et al., 1981, Ross et al., 1983), willingness to seek treatment (Kessler et al., 1981), permission to cry when depressed (Hammen and Padesky, 1977), mechanisms of coping with depressive mood (Ruble et al., 1993), depressive symptom profiles (Young et al., 1990, Ernst and Angst, 1992), effects of female hormones in menstrual cycle, menopause, and postpartum period (Andersch et al., 1986, Johnson et al., 1988, Ballinger, 1990, Richards, 1990). However, the ultimate reason for this finding has remained unclear (Smith and Weissman, 1992).
One more possibility, not often considered, for explaining this gender difference in depressive symptoms is that the instruments or some of their questions or statements, used for the detection of depression or depressiveness, are related more to the female gender than to the depression itself. Indeed, some studies have found no gender difference in depression (Romanoski et al., 1992) and in depressive symptoms (Wilhelm and Parker, 1989, Salokangas et al., 1996). Thus, it is possible that different instruments can give different results regarding gender differences in depression and depressive symptoms. This question relating to depressive symptoms was studied in a community survey by using two different screening instruments the Beck Depression Inventory (BDI) and the Depression Scale (DEPS). In support of the comparison of two screening instruments it can be argued that, in community studies, screening usually precedes the diagnostic interview and is thus a decisive stage in selecting subjects for further studies. Additionally, many studies deal with depressive symptoms measured by self-report instruments.
Our hypothesis was that, both at the absolute level and when compared with each other (e.g. using one as the gold standard for the other and vice versa), these two screening instruments detect depressiveness differently in men and women, and that this gender difference is due to the items which produce the same gender differences even among persons without depressive symptoms.
Section snippets
Subjects and method
This study is a part of a larger community survey and intervention study: The Outcomes of Depression International Network (the ODIN project). The subjects were randomly selected from all 18- to 64-year olds living in the south-western part of Finland. About half of the subjects lived in the city of Turku and the other half in the rural area near Turku. The questionnaire, including the BDI, was mailed to the subjects to screen depressive and non-depressive individuals for further interviews and
Results
There was no difference in the DEPS sum score between men and women. The gender difference in the BDI sum score was not statistically significant although P was 0.051: females had higher sum scores than males (Table 1). There were significant differences between age and marital status groups on both in DEPS and BDI scores. The correlation between DEPS and BDI was r=0.815 (P=0.000). The DEPS and BDI scores correlated equally with the number of confidants (r=−0.282; P=0.000 and r=−0.253; P=0.000)
Discussion
The major finding of the present study was that the two screening instruments of depressive symptoms, although having a very high inter-correlation, similar correlations with some other depression-related variables and similar distributions according to age and marital status, behaved differently in males and females. Thus, the first part of the hypothesis was clearly supported. Additionally, BDI produced, on many items, higher scores for females than males in the total sample, and this was
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