BALTIMORE – Anna-Lisa Munson, MD, MPH, of Denver Health Medical Center in Colorado, told attendees at the Pediatric Academic Societies annual meeting.
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Although several studies in adults have suggested a link between vitamin D deficiency and depression, no large-scale studies have investigated whether such a relationship exists in adolescents, up to half of whom have a vitamin D deficiency, Dr Munson said.
The researchers relied on National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2010 to assess prevalence of major depressive disorder and vitamin D 25-hydroxy levels in teens aged 12-17 years. Serum vitamin D levels of less than 30 nmol/L were considered deficient while 30-50 nmol/L was considered insufficient, and at least 50 nmol/L was sufficient. A score between 10 and 27 on the Patient Health Questionnaire-9 (PHQ-9) qualified as depression.
The researchers adjusted their findings for age and sex, as well as other covariates linked to vitamin D levels or depression in previous research: latitude, season, race/ethnicity, and poverty to income ratio.
Among the 2,815 participants who completed the National Institute of Mental Health Diagnostic Interview Schedule for Children (NIMH-DISC), 8% had major depression. Among the 2,420 of participants with serum vitamin D values, 8% had vitamin D deficiency, 33% had insufficiency, and 59% had sufficiency.
Risk of depression dropped 10% for every additional 10 nmol/L of vitamin D, the analysis showed (odds ratio, 0.90).
Although non-Hispanic white students had about twice the odds of depression as other ethnic groups, risk of depression did not vary according to gender, age, season, latitude, poverty to income ratio, or use of vitamin D supplements.
The findings are limited by the cross-sectional data and lack of data regarding other factors that could affect vitamin D absorption, such as sunscreen use or clothing worn in the sun. The researchers also had only broad – not precise – data on latitude, and the PHQ-9 was used as a proxy for major depression instead of a clinical diagnosis.
The research was funded by the Denver Health Division of General Pediatrics. The authors had no relevant financial disclosures.