To the best of our knowledge, this is the first meta-analysis to investigate whether Kawasaki disease elevates the risk of neurodevelopmental disorders. The study suggests that there is an increased risk of ADHD in individuals who had been diagnosed with Kawasaki disease compared to the general healthy population. However, Kawasaki disease does not contribute significantly to the risk of future intellectual disability or ASD. Furthermore, upon closer examination of cognitive function, Kawasaki disease seemed to have no significant effect on the differences in intelligence quotient test scores.
This study indicates that survivors of Kawasaki disease have a higher likelihood of being diagnosed with ADHD later on. ADHD has been consistently linked to neuroinflammatory states in many previous studies (36, 37), which aligns with relevant clinical research indicating that Kawasaki disease patients exhibit a decline in internalizing and attentional behavior during subsequent follow-ups (34). Kawasaki disease has been found in past research to be associated with various immune disorders including atopic dermatitis, asthma, and allergic rhinitis (38), which stems from allergic reactions dominated by T Helper 2 cells and eosinophils (1, 39, 40). ADHD has also been found to be associated with allergic diseases (41, 42). In addition, ADHD has been linked to cellular and humoral immune responses, with higher detectable levels of IL-2, IL-5, IL-10, and TGF-beta in the cerebrospinal fluid (43) and higher serum concentrations of IL-6 and IL-10 in children with ADHD (44). Furthermore, elevated levels of pro-inflammatory markers have been found to be positively correlated with the severity of ADHD symptoms (45). These immune mechanisms may interact further with the dopamine system in the basal ganglia, potentially generating ADHD-related symptoms (46, 47). Similar to ADHD, there is also ample evidence to suggest that the pathogenesis of Kawasaki disease is closely related to the immune system. The association of Kawasaki disease with cytokines including IL-6, IL-8, and IL-17, has been mentioned in several studies (1, 48, 49). The development of coronary artery aneurysms in Kawasaki disease is also associated with the infiltration of neutrophils, macrophages, lymphocytes, and dendritic cells into the endothelial cells of blood vessels (50, 51). Based on the aforementioned evidence, it can be understood that immune mechanisms are involved in the development of ADHD, as well as subsequent neurological and cognitive symptoms.
Our meta-analysis showed that Kawasaki disease does not significantly increase the risk of intellectual disability. This is contrary to previous studies which indicated that, in the Kawasaki disease population, reaching a level of systemic vasculitis may lead to reduced cerebral perfusion (52), potentially resulting in deficits in intelligence and cognitive function during development (53), and is also associated with a higher incidence of coronary artery lesions (52, 54). However, previous cohorts have shown that Kawasaki disease patients who developed coronary artery lesions experienced no significant effects on their cognitive function (30). In short, only a few cases of Kawasaki disease will develop severe central nervous system symptoms (7) or systemic vascular lesions (55), therefore not significantly increasing the risk of intellectual disability. Regarding the risk of ASD in the Kawasaki disease population, this study indicates no increased propensity. While past research suggested that ASD might be an immune disorder induced by allergies and associated with autoantibodies such as anti-myelin basic protein and anti-myelin associated glycoprotein (56), current meta-analysis evidence does not support an association between Kawasaki disease and an elevated risk of ASD. More evidence is needed to determine whether this immune response affects brain development and contributes to ASD.
This study has several limitations. Firstly, there is limited research on the association between Kawasaki disease and neurodevelopmental disorders. The few studies available for each condition were predominantly conducted in Taiwan and Canada, thus raising concerns about representativeness. However, the included studies utilized national-level databases for long-term follow-up, providing some degree of reference value. Secondly, since the included studies relied on data from insurance databases, diagnoses of Kawasaki disease and neurodevelopmental disorders were based on diagnostic codes without clear documentation of the diagnostic instruments or tools used, potentially resulting in variations in the severity of these conditions that remain unknown. Thirdly, another issue arising from the use of insurance databases is the presence of unknown potential confounders, despite the included studies adjusting for potential confounding factors using adjusted HRs.