Autism spectrum disorders: Autonomic alterations with a special focus on the heart

Abstract

Autism spectrum disorders (ASD) is a heterogeneous group of developmental disorders characterized by stereotyped behaviors and thoughts, and deficits in social behavior, interactions, and communication. The epidemiological evidence shows an increase in the prevalence of ASD although the etiology and pathology of ASD are still largely unknown. In addition to the core symptoms, patients with ASD show emotional and cognitive deficits, and are thought to suffer from abnormal levels of arousal and therefore increasingly studies have been performed to investigate alterations in the autonomic nervous system. The aim of the review is to focus on the changes in the cardiovascular system. Overall, the literature provides some evidence for an increase in baseline heart rate (HR) and a decrease in HR variability (HRV), specifically for high-frequency respiratory sinus arrhythmia. However, the review also illustrates the large variability in results. This is in part due to differences in methodology, but also to the heterogeneity of ASD per se. Moreover, as ASD already occurs at a very young age, differences in the age of the patients are also likely to play a role. Therefore, we propose a more systematic analysis of autonomic dysfunction in well-defined patient populations. In addition, given the plethora of genetic and environmental animal models for ASD that have been developed in recent years, we argue that investigation of HR and HRV could substantially improve the translational validity of these models.