Atopic dermatitis (AD) shows a "dose-dependent association" with learning disability, American researchers report.

A cross-sectional study enrolled 2,074 children with AD aged between two and 17 years. All the children previously received pimecrolimus. Overall, 8.2 per cent reported a diagnosed learning disability.

After allowing for sex, age, race, ethnicity, household income, age at AD onset, family history of AD and comorbidities, participants with mild AD on clinicians’ assessment were 72 per cent more likely to have a learning disability than controls with clear or almost clear skin.

Those with moderate and severe to very severe AD were twice and three times more likely to have a learning disability respectively.

Based on self-reported severity the risk of learning disability was about double (odds ratios of 1.68, 1.97 and 2.48 for mild, moderate and severe AD respectively) compared with controls.

Future studies should characterise the timing, phenotypes and causal mechanisms of learning disability associated with AD, say the authors. In the meantime, they suggest screening children with “more severe AD” for learning disabilities.