Background: Because aeroallergens produce inflammation in the respiratory airways, and inflammation triggers depression in vulnerable individuals, we hypothesized that mood sensitivity to pollen, the most seasonal aeroallergen, will be associated with a greater seasonality of mood. Since pollen is absent during winter, we specifically predicted that mood sensitivity to tree pollen will predict non-winter SAD but not winter SAD.
Methods: A convenience sample of African and African American college students who lived in the Washington DC metropolitan area for at least the past 3 years completed the Seasonal Pattern Assessment Questionnaire (SPAQ), from which the Global Seasonality Score (GSS) was calculated, a diagnosis of cumulative SAD (syndromal or subsyndromal SAD) was derived, a seasonal pattern (winter vs non-winter) identified, and self-reported mood changes during high pollen counts obtained. A Mann-Whitney test was used to compare GSS between participants with vs without mood worsening during high pollen counts. The capability of mood worsening with high pollen counts, gender, ethnicity, and age to predict non-winter SAD was analyzed with logistic regressions.
Results: GSS was greater (z=5.232, p<0.001) in those who reported mood worsening with high pollen counts. Mood sensitivity to pollen predicted non-winter SAD (p=0.017), but not winter SAD.
Limitations: The SPAQ is not a definitive tool to assess seasonality, and self-reported mood worsening with high pollen counts relies on recollection. No direct measures of depression scores or pollen counts were collected. The non-winter SAD concept has not been previously established.
Conclusions: Our study, which should be considered preliminary in light of its limitations, suggests that self-reported mood-worsening with high pollen count is associated with a greater seasonality of mood, and predicts SAD of non-winter type.