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Suicide and decompensation of mental illness peaks in spring and to a lesser extent in fall. Several recent studies reported that suicide and decompensation peaks coincided with spring and fall aeroallergen peaks. Allergic symptoms occur as the result of a complex biochemical cascade initiated by IgE antibodies (sensitization) and allergens (triggers). Animal models have shown molecular/neurochemical changes in the brain as well as relevant behavioral changes associated with this IgE mediated biochemical cascade. These factors suggest that seasonal allergy could precipitate suicidality and mood instability. In the current study, we compared the prior suicide attempt and decompensation history in allergen sensitive and nonsensitive persons diagnosed with mood disorders. Patients with Major Depressive Disorder or Bipolar I or II Disorder (n=80) completed several instruments (Columbia Suicide History Form, Beck Scale of Suicidal Ideation and Beck Suicide Intent Scale). Serum was screened for allergen-specific IgE antibody. t-Test analysis was used to compare the history of suicide attempts and instability between the two groups, aeroallergen positive and negative. Further, we compared the ratio of attempts and decompensations during the allergy season to suicides in both groups occurring during the rest of the year. There were no statistical differences in any measurement performed between the psychologically ill and well groups. In contrast to previous studies that found an association between completed suicide and allergen exposure or prior history of allergy, the current study found no association between number or timing of prior suicide attempts and markers of allergic sensitization in patients with recurrent mood disorders.

Keywords: Environment, allergen, mood disorders, suicide, psychiatry.