Examining the Link Between Depression and Seasonal Allergies
Condition: Depression
MeSH terms: Depression; Depressive Disorder
Study type: Observational

Summary: 
      This study will examine whether spring and fall seasonal depression in individuals with high
      sensitivity to pollen is linked to seasonal increases in tree and ragweed pollen.
    

Detailed description: 
      Those who suffer from depression have their normal lives interrupted by symptoms such as
      persistent sad thoughts, inability to feel pleasure, and potential suicide. Suicide and
      depression peak in the spring and fall. Worsening of depression, admission to a hospital for
      depression and bipolar depression, and use of electroconvulsive therapy for treatment of
      depression all peak in the spring. Although seasonal affective disorder (SAD), in which
      depression corresponds with seasonal changes, is commonly associated with the winter subtype,
      SAD is actually more prevalent as the spring subtype.

      Allergies, which also peak in the spring and fall, have been linked to depression. Allergic
      reactions release cytokines, which are proteins that mediate the immune system response when
      a foreign substance enters the body. Previous studies have found both that an increase in
      cytokines in otherwise healthy individuals causes depressive symptoms and that cytokines
      cause the chemical tryptophan (TRP) to switch from producing serotonin, a neurotransmitter
      associated with feelings of well-being, to producing kynurenine (KYN), a potentially toxic
      chemical. To determine whether and to what extent allergies are linked to depression, this
      study will compare depression levels of participants with and without allergies before and
      during peak times for seasonal allergies. Results from this study may be used in further
      research to examine the effects of allergy prevention on depression.

      Participants in this study will meet with researchers three times. At the first visit, they
      will be screened for allergies and give their demographic information. The timing of the
      second and third visits will depend on each participant's allergies. Those with spring
      allergies will be tested before and then during the spring allergy season. Those with fall
      allergies or with no allergies will be tested before and then during the fall allergy season.
      On the second and third visits questionnaires and clinical interviews will assess depression
      symptoms, and blood tests will be performed to measure chemical levels of cytokines, TRP, and
      KYN. During these visits participants will also be asked to complete a sleep log for 1 week.
      This will entail describing their sleep, activity, caffeine consumption, alcohol consumption,
      and use of sleep medications. A subgroup will wear an Actiwatch device, which electronically
      monitors sleep and wakefulness cycles, for 1 week, 24 hours a day.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        A community sample will be recruited via local press and radio advertising. Referrals from
        mental health providers will be used to supplement this population.
      
Biospecimen description: 
      Serum
    
Keywords: Mood Disorders; Major Depressive Disorder; Bipolar Disorder; Tree Pollen; Ragweed Pollen; Rhinitis; Allergic; Seasonal; Allergens