The immune system and the nervous system interact and modulate each other. The objective was to determine whether neurodevelopmental abnormalities are associated with allergic dermatitis and higher IgE levels. This case-control study is based on a cohort of patients at neurological risk, including neonates with intraventricular haemorrhage and secondary hydrocephalus, periventricular leukomalacia, and neonatal asphyxia. In 2017 and 2018, infants with neurodevelopmental disorders, allergic dermatitis, or both, were identified. IgE levels were measured in all participants, some of whom had outliers immunoglobulin levels. An ethics committee approved the study, and the parents signed the informed consent. The following were calculated: relative risk and t-test using frequentist and Bayesian methods; the results are presented through tables and comparative graphs. The risk of developing allergic dermatitis tripled in infants with neurodevelopmental disorders and those exposed to environmental allergens. Using the frequentist t-test, higher levels of IgE were found in patients diagnosed with allergic dermatitis and those in contact with environmental allergens. With the Bayesian t-test, besides the previous results, higher levels of IgE were also found in children with neurodevelopmental disorders. Comparing both statistical methods' results, it is found that there are significant differences and a type II error with the frequentist method since the presence of atypical values drags the mean to an unrealistic value. Bayesian statistics have advantages: The size of the sample and the losses to follow-up do not affect the results; they adapt to any data structure, regardless of the homoscedasticity of the variances or the presence of normality; and it is a robust model against outliers. The present work confirms the bidirectional communication between the nervous system and the immune system because neurodevelopmental disturbances are associated with allergic dermatitis and an increased level of IgE. However, more studies are needed to confirm this hypothesis because environmental allergens also modulate the development of allergies.