Some Biochemical Implications in Autism Spectrum Disorder

Abstract

Autism spectrum disorder (ASD) affects 0.6 to 1% of the population worldwide. It is characterized by a deficit in communication and social interaction, and is associated with restricted and repetitive behavior patterns. Stereotypes include inflexible adhesion to specific non-functional routines and rituals and a persistent concern with parts of objects rather than the object as a whole. Up to the present time, there are no specific tests that permit a laboratory diagnosis of the disorder to be carried out, and the syndrome is confirmed by clinical observation in the first 36 months of the patient’s life. Clinical manifestations such as epilepsy, mental retardation, sleep disorders, hyperactivity, irritability and auto- and heteroaggressiveness may alter the patient’s prognosis. Around 50% of children with ASD fulfill the criteria for attention deficit hyperactivity disorder (ADHD). Symptoms of oppositional defiant disorder (ODD) associated with autism appear to indicate a distinct phenotype requiring specific therapeutic measures. ASD is not a discrete nosological entity but, rather, a multifactorial syndrome associated with different phenotypic and biological presentations. Various disorders such as pathologies of the gastrointestinal tract have been linked to ASD, not only insofar as causality is concerned but also with respect to their role in aggravating the disease. Other associated disorders include lesions in physiological processes such as the redox metabolism, mitochondrial dysfunction and enzymatic regulation of essential metabolites. Currently, studies on direct and indirect markers of mitochondrial metabolism associated with anomalies found in the brain of these patients point to the possibility of these markers being used as tools with which to reach a diagnosis that would be laboratory based rather than merely clinical.