Reply to: The geographic variation in the prevalence of attention-deficit/hyperactivity disorder the United States is likely due to geographical variations of solar ultraviolet B doses and race

Vitamin D levels in children with attention deficit hyperactivity disorder: Association with seasonal and geographical variation, supplementation, inattention severity, and theta:beta ratio

We examined seasonal and geographic effects on vitamin D [25(OH)D] levels, association with attention-deficit/hyperactivity disorder (ADHD) symptom severity, and effects of supplementation in 222 children age 7-10 with rigorously diagnosed ADHD. 25(OH)D insufficiency rates were 47.2 % in Ohio and 28.5 % 400 miles south in North Carolina. Nadir of 25(OH)D levels was reached by November in Ohio, not until January in NC. Thirty-eight children with insufficiency/deficiency took vitamin D (1000-2000 IU/day for a month); levels rose 52 %. Although inattention did not correlate with 25(OH)D at screen nor improve significantly with supplementation, inattention improvement after supplementation correlated with 25(OH)D increase (rho = 0.41, p = 0.012). A clinically significant proportion of children with ADHD have insufficient 25(OH)D even at summer's end, more so in the winter and north of the 37th parallel. The significant correlation of inattention improvement with 25(OH)D increase suggests further research on 25(OH)D as ADHD treatment.

Sleep, chronotype, and sleep hygiene in children with attention-deficit/hyperactivity disorder, autism spectrum disorder, and controls

Sleep problems are highly prevalent in ADHD and autism spectrum disorder (ASD). Better insight in the etiology is of clinical importance since intervention and prevention strategies of sleep problems are directed at underlying mechanisms. We evaluated the association of sleep problems and sleep patterns with sleep hygiene (behavioral/environmental practices that influence sleep quality, e.g. caffeine use), access to electronic media, chronotype, and anxiety/depression in children aged 6-12 years with ADHD, ASD, or typical development (TD) using parental questionnaires. ANOVA and linear regression analyses were adjusted for age and sex. Children with ADHD and ASD showed more sleep problems (63.6 and 64.7%, vs 25.1% in TD) and shorter sleep duration than controls, while differences between ADHD and ASD were not significant. Sleep hygiene was worse in ADHD and ASD compared to TD, however, the association of worse sleep hygiene with more sleep problems was only significant in ASD and TD. There was a significant association of access to electronic media with sleep problems only in typically developing controls. Chronotype did not differ significantly between groups, but evening types were associated with sleep problems in ADHD and TD. Associations of greater anxiety/depression with more sleep problems were shown in ADHD and TD; however, anxiety/depression did not moderate the effects of chronotype and sleep hygiene. We conclude that sleep problems are highly prevalent in ADHD and ASD, but are differentially related to chronotype and sleep hygiene. In ASD, sleep problems are related to inadequate sleep hygiene and in ADHD to evening chronotype, while in TD both factors are important. Clinical implications are discussed.