Dr Amir Khan and colleagues at the Medical College of Virginia in the US examined male-female dizygotic twin pairs in which both twins fulfilled the DSM-III-R criteria for lifetime major depression.

Telephone interviews were conducted in 1,404 complete adult pairs of opposite-sex dizygotic twins registered on a population list for Virginia. This yielded 201 pairs in which both twins fulfilled the recruitment criteria.

Dichotomous and continuous variables within the pairs were measured using the McNemar’s chi-square analysis and conditional logistic regression, respectively.

After controlling for age at onset of depression and help-seeking behavior, gender differences in depressive symptomology between the sexes were observed.

Female twins reported significantly more fatigue, hypersomnia and psychomotor retardation than male twins during their most severe depressive episode.

Conversely, male twins complained of insomnia and agitation during their most severe episode.

Appetite or weight change did not differ between male and females, which is contrary to previous research.

The authors said there are many plausible explanations for the observed gender differences, ranging from “the effects of recall, social roles and cultural norms and adverse life events to different exposure to gonadal hormones, dysregulation of the adrenal axis and genetic factors”.

“These results may further substantiate our previous finding that some genetic risk factors influencing liability to major depression in men and women might act differently,” Dr Khan’s team speculate.

They caution that there were methodological limitations to their study and that the results cannot be extrapolated to non-Caucasian ethnic groups.

Reference: Khan et al, American Journal of Psychiatry 2002;159:1427-1429

© Health Media Ltd 2002
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