The seasonal spring peak in suicide rates is particularly high among patients with a history of mood disorders, research shows.

Previous research has consistently shown a spring peak in suicide rates and exacerbations of mood disorders, which is “conducive to a hypothesis that the Spring peak in suicide is driven by a seasonal decompensation of mood disorders in spring,” explain Teodor Postolache (University of Maryland School of Medicine, Baltimore, USA) and team.

“If so, one would expect a greater suicide peak in spring among individuals with a history of hospitalization for mood disorders,” they add.

To investigate, the researchers used the Danish Cause of Death Registry to identify all 37,987 individuals who died by suicide in the country between 1970 and 2001.

They also used the Danish Psychiatric Central Register to assess any history of mood disorders among the suicide victims.

The team found that, overall, 17.1% of the suicide victims had been previously hospitalized for bipolar disorder, unipolar depression, or other mood disorders.

A spring peak in suicide rates was evident in individuals with and without a history of hospitalization for mood disorders, but was more prominent in those with such as history.

Specifically, men and women with a history of hospitalization for mood disorders were 1.18 and 1.20 times, respectively, more likely to commit suicide in spring than at other times of the year, while the respective risks in men and women without such a history were 1.07 and 1.11.

Analysis of a smaller sample of suicide victims from between 1981 and 1997, which allowed for adjustment of socioeconomic factors, indicated that a history of hospitalization for mood disorders was associated with a greater risk for spring suicide in men than women, at relative risks of 1.25 and 1.20, respectively.

Postolache and team conclude in the Journal of Affective Disorders: “The key finding of this study suggests that the history of hospitalization for mood disorder increases the spring peak of suicide.”

They add: “The results support the need to further investigate if exacerbation of mood disorders in spring triggers seasonal peaks of suicide. Identifying triggers for seasonal spring peaks in suicide may lead to uncovering novel risk factors and therapeutic targets for suicide prevention.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

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