Summary:
Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition characterised by persistent patterns of inattention, hyperactivity, and impulsivity, often beginning in childhood and continuing into adulthood. Twin studies suggest a strong genetic contribution, although environmental and perinatal influences such as preterm birth and growth restriction also contribute to risk. Emerging research has increasingly examined potential links between ADHD and immune-related conditions, including autoimmune diseases. Conditions such as psoriasis, inflammatory bowel disease, asthma, coeliac disease, and autoimmune thyroid disorders have all been reported in association with ADHD. This population-based cross-sectional study used Norwegian national registry data from 2,500,118 individuals to investigate whether ADHD is associated with a range of autoimmune diseases and whether these associations differ by sex. The findings showed that ADHD was associated with increased odds of several autoimmune conditions, with the most consistent findings observed for psoriasis and inflammatory bowel disease. The association between ADHD and psoriasis was present in both sexes but was stronger in females. For inflammatory bowel disease, a sex-specific pattern was observed, with females showing increased odds of Crohn’s disease and ulcerative colitis, while males showed reduced or no associations. In summary, this study provides evidence of associations between ADHD and certain autoimmune diseases, particularly psoriasis and inflammatory bowel disease, with notable sex-specific differences. These results support the hypothesis that immune-mediated and neurodevelopmental processes may be interconnected, and highlight the importance of considering sex differences in future research on ADHD and autoimmune disease comorbidity.
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Abstract:
Several studies have demonstrated associations between neuropsychiatric disorders, such as attention-deficit/hyperactivity disorder (ADHD), and the immune system, including autoimmune diseases. Since ADHD and many autoimmune diseases show sex-specific properties, such associations may also differ by sex. Using Norwegian national registries, we performed a cross-sectional study based on a cohort of 2,500,118 individuals to investigate whether ADHD is associated with common autoimmune diseases. Associations between ADHD and autoimmune diseases in females and males were investigated with logistic regression and effect modification by sex was evaluated. Several subanalyses were performed. The strongest association was found between ADHD and psoriasis in females, adjusted odds ratio (adjOR) = 1.57 (95% confidence interval: 1.46–1.68) and males, adjOR = 1.31 (1.23–1.40); p value for interaction < 0.0001. Furthermore, among females, ADHD was associated with Crohn’s disease, adjOR = 1.44 (1.16–1.79) and ulcerative colitis, adjOR = 1.28 (1.06–1.54). In contrast, males with ADHD had lower odds of Crohn’s disease, adjOR = 0.71 (0.54–0.92), in addition to a trend for lower odds of ulcerative colitis, adjOR = 0.86 (0.71–1.03); p values for interaction < 0.0001 and 0.0023, respectively. In a group of females where information on smoking and body mass index was available, adjustment for these potential mediators did not substantially alter the associations. Our findings support previously reported associations between ADHD and diseases of the immune system. The associations differ by sex, suggesting that sex-specific immune-mediated neurodevelopmental processes may be involved in the etiology of ADHD.
Article Publication Date: 09/05/2017
DOI: 10.1007/s00787-017-1056-1
