Despite intense speculation about a possible link between the rates of administration of the MMR vaccine and an increase in the incidence of autism, the underlying biochemical mechanisms of the condition remain unknown. In May Annals of Neurology Karin Nelson and colleagues from the National Institute of Neurological Diseases and Stroke, Bethesda, US show that children with autism have an increase in certain neuropeptides and neurotrophins in their peripheral blood from the first days of life.

Nelson et al studied archived neonatal blood from children with autism, mental retardation, cerebral palsy and control children using recycling immunoaffinity chromatography to measure biological regulators of cerebral development. They found that concentrations of vasoactive intestinal peptide, calcitonin gene-related peptide, brain-derived neurotrophic factor CGRP and neurotrophin 4/5 were significantly higher in children with autism and in those with mental retardation without autism than in controls (Annals of Neurology 2001, 49:597-606). Concentrations...