Association between attention deficit hyperactivity disorder and keratoconus

To investigate the relationship between attention deficit hyperactivity disorder (ADHD) and keratoconus (KC) in a large, diverse adult cohort.

Retrospective cross-sectional study.

Individuals with and without ADHD from the National Institutes of Health All of Us Research Program.

Individuals with ADHD were propensity-score-matched (1:3) to controls. Univariable and multivariable conditional logistic regression models were used to evaluate the association between ADHD and KC, with adjustments for psychiatric comorbidities, atopic conditions, obstructive sleep apnea, ADHD medications, conjunctivitis, and tear-film-related disorders. An interaction term analysis was performed to assess potential effect modification by sex.

A total of 40 360 matched participants were included, comprising 10 090 individuals with ADHD and 30 270 without ADHD (mean age: 42.3 ± 15.6 years; mean body mass index: 30.5 ± 8.4 kg/m²; 63.1% female). The prevalence of KC was significantly greater among individuals with ADHD (33 of 10 090; 0.33%) compared with matched controls without ADHD (42 of 30 270; 0.14%), yielding an unadjusted odds ratio (OR) of 2.36 (95% CI 1.49-3.72, P < 0.01). The participant's sex did not significantly modify this association (P = 0.38). After multivariable adjustment, the association between ADHD and KC remained significant (OR 2.43, 95% CI 1.28-4.61, P = 0.01), with tear-film-related disorders emerging as an independent predictor of KC (OR 5.37, 95% CI 2.62-11.01, P < 0.01).

In this large, diverse adult cohort, individuals with ADHD were more than twice as likely to have KC, independent of multiple confounders. Tear-film-related disorders, which may potentially represent a proxy for eye rubbing, also emerged as a significant predictor.