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Ask the Mental Health Expert Archives 2001-2004

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Bipolar & Seasons

Q. I am a therapist fresh out of school working in a partial hospitalization setting. Beginning in late February, I noticed an extreme increase in the amount of bipolar patients I was being consulted on in our local emergency room and in our program.

I have read one study on the influence of seasons on bipolar disorder, but that is all I have ever heard. The patients that I saw were in extreme states, mostly mania with psychosis. Can you give me an idea of what effects the season changes have on bipolar symptoms? Are there any other studies that you are familiar with?

A. The evidence of seasonal changes in bipolar disorder is a bit mixed, and may depend on the light exposure of the country being studied. For example, one Finnish study [Hakkarainen et al, BMC Psychiatry. 2003 Jun 9 [Epub ahead of print]. Epub 2003 Jun 09] like-sex twins born from 1940 to 1969 were screened for a diagnosis of bipolar type I disorder. Bipolar twins were then compared with their healthy co-twins. Bipolar twins had greater seasonal changes in sleep length (p=0.01) and mood (p=0.01), and higher global seasonality scores (p=0.03) as compared with their co-twins with no mental disorder. Sunny days (p=0.03) had a greater positive effect on well being in the bipolar than healthy co-twins.

Consistent with the concept of seasonal effects in bipolar disorder, Schaffer et al [Can J Psychiatry. 2003 May;48(4):277-80.] found that 14 of 62 (22.6%) Canadian subjects with bipolar disorder had a seasonal pattern to their illness. In a larger study, D'Mello et al [Ann Clin Psychiatry. 1995 Mar;7(1):11-8] studied 377 bipolar disorder patients over a 6-year period. The seasonal variation of hospitalization, total sleep time, aggressive behavior, and treatment outcome were analyzed.

Among men, the admission rate peaked in the springtime. Women demonstrated a bimodal seasonal distribution, with peak admission rates in spring and fall. Aggressive behavior in both men and women peaked in the spring. These findings parallel previous reports regarding the influence of seasons upon bipolar disorder, and could be consistent with your observations of an increase in late February.

On the other hand, another Canadian study (Whitney et al, : J Affect Disord. 1999 Oct;55(2-3):99-105) found somewhat mixed results in a retrospective (75-year!) study. They found that for mania and depression, there was no statistically significant seasonal pattern of admissions. In contrast, mixed state admissions (patients with both manic and depressive features) peaked in the summer.

Finally, the literature on so-called seasonal affective disorder (SAD) may interest you, since it has always noted that many SAD sufferers show hypomanic mood swings in springtime (versus winter depression).

On the other hand, the trend you have observed could simply have been a fluke--but keep watching, and maybe consider publishing your findings!

Other Resources:

November 2003

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