Vitamin D and Depressive Symptoms in Children with Cystic Fibrosis

Background: Vitamin D deficiency has been hypothesized to play a role in the development of depression. Hypovitaminosis D is almost universal in patients with cystic fibrosis (CF). No studies to date have explored associations between serum concentrations of 25-hydroxyvitamin D (25(OH)D), a standard measure of vitamin D, and depression in patients with CF. Objective: This pilot study aimed to explore the relationship between 25(OH)D and the presence of depressive symptoms among youth with CF. Methods: A cross-sectional study was conducted at an ambulatory Cystic Fibrosis Center clinic. Serum 25(OH)D and Children's Depression Inventory (CDI) scores were analyzed from 38 youths with CF ages 7-17 years. Child depressive symptoms were measured using the CDI, with scores above 12 indicating a significant level of depressive symptoms. Serum 25(OH)D concentration were measured using the liaison 25 OH vitamin D assay. Insufficient vitamin D status was defined as a circulating 25(OH)D concentration less than 30 ng/mL. Results: Insufficient vitamin D levels were found in 59% of patients; 28% of patients had significant levels of depressive symptoms on the CDI (scores >12). Serum 25(OH)D was negatively associated with CDI scores (r = -0.55; p < 0.001), and the group of patients with insufficient 25(OH)D levels indeed reported significantly more depressive symptoms (t = 4.26; p < 0.001). Conclusions: 25(OH)D insufficiency was associated with depressive symptoms in this cohort of youth with CF. Future rigorous studies investigating vitamin D and depression in CF are warranted with larger sample sizes using confirmatory methods to diagnose depressive disorders.