In high-income countries, it is known that suicide rates are three to four times higher in men than in women. In contrast, population surveys indicate that the prevalence of depression, suicidal thoughts and suicide attempts are higher in women than in men.

There are several possible explanations for these different patterns. First, men use more lethal methods of suicide than women, so fatality is higher in men. Second, women with depression are more likely to seek help from friends, family and health services than men.

Last, it is possible that depression is more stigmatised in men than in women, so men may be less likely to report symptoms.

The Nord-Trondelag Health Study was carried out in 1995-1997 among 50,692 Norwegians aged 20 and over. Participants completed a questionnaire designed to measure depression and anxiety.

The researchers then used the death registry to identify all deaths up to the end of December 2004.

Published in the June 2008 issue of the British Journal of Psychiatry, the study found that at baseline 5.9% of the women and 4.8% of the men had mixed anxiety and depression.

At the end of the study period, 14 women and 27 men had died by suicide. Only 11 suicides occurred among people with mixed anxiety and depression at baseline. It was noteworthy that there were no suicides among participants with ‘pure’ depression.

The researchers comment that, if real, these gender differences could be explained in two different ways. First, they could reflect a more severe symptom profile in men with self-reported anxiety and depression (perhaps because of gender differences with regard to the stigma associated with mental illness).

Second, they could be accounted for by the way in which men respond to mental illness (for example, self-medication or help-seeking).

In keeping with previous research from Scotland, the results of this study suggested a higher suicide risk in men than in women with mixed anxiety and depression, but there was no statistical evidence to support such a difference. Both studies were relatively small, and sizeable gender differences cannot be ruled out.

Surprisingly, the researchers say, the majority of suicides in this study occurred among people who had not been diagnosed as depressed or anxious. Half of all suicides were not mentally ill at baseline, indicating either under-reporting of psychiatric symptoms or, more plausibly, the relatively transient nature of common mental disorder.

The researchers conclude that these findings provide some support for the idea that gender differences related to the risk of depressive disorders and suicide are due to gender differences in the reporting of psychiatric symptoms.

Other factors may include gender differences in help-seeking, acceptable suicide methods, depressive symptom profile and the psychiatric conditions contributing to population suicide rates.