Early antibiotic exposure not a risk factor for ADHD

Exposure to antibiotics during the first year of life does not appear to contribute to an increased risk of developing attention-deficit/hyperactivity disorder (ADHD), as found in a recent study.

The study included a cohort of 187,605 children (51.2 percent male; 54.2 percent residing in urban regions). Of the participants, 84,424 (45.0 percent) filled at least one antibiotic prescription during the first year of life, among whom 75.1 percent received one or two courses, 55.2 percent received antibiotics for ≤2 weeks, and 58.2 percent received a penicillin antibiotic.

Over a median of 10.1 person-years of follow-up, 16,290 children (8.7 percent) received an ADHD diagnosis at a mean age of 8.05 years. Crude incidence rates of ADHD were 9.8 cases per 1,000 person-years in the antibiotic-exposed group and 6.7 cases per 1,000 person-years in the unexposed group.

Researchers then matched antibiotic-exposed and unexposed children using high dimensional propensity scores (n=69,738). Cox proportional hazards analysis revealed no association between ADHD risk and antibiotic exposure (hazard ratio [HR], 1.02, 95 percent CI, 0.97–1.08). A separate sibling cohort (n=67,671) confirmed the result, with the HR for ADHD being 0.96 (0.89–1.03).

In secondary analyses of the matched cohort, a risk increase in ADHD was seen in the subgroup of children exposed to ≥4 antibiotic courses or a treatment duration of >3 weeks. These associations were, however, not replicated in the sibling cohort.

More studies are needed to examine antibiotic exposure at other stages of childhood, as well as to explore the risk of childhood diseases resulting from antibiotic-induced microbiota changes at the biological level, according to the researchers.