Methylglyoxal, advanced glycation end products and autism: is there a connection?

Autism is a complex and heterogeneous neurodevelopmental disorder of unknown etiology but very likely resulting from both genetic and environmental factors. Recent estimates suggest that it affects 1 in 100-150 individuals in the US. Oxidative stress, inflammation and mitochondrial dysfunction have all been suggested to play key roles in autism and may be linked via alterations in cellular redox homeostasis. The glutathione/glutathione disulfide (GSH/GSSG) redox pair forms the major redox couple in cells and as such plays a critical role in regulating redox-dependent cellular functions. A number of studies have shown that variations in genes involved in GSH metabolism are associated with autism. GSH also modulates the activity of glyoxalase 1 (Glo-1), the rate-limiting enzyme for the removal of reactive dicarbonyls such as methylglyoxal (MG). MG is the major precursor for the formation of advanced glycation end products (AGEs). Both MG and AGEs can induce oxidative stress, inflammation and mitochondrial dysfunction and are implicated in diabetic complications and multiple, age-related neurological diseases. Dietary consumption of AGEs and MG correlates with food intake which has increased 20-30% over the past 20 years. Both MG and AGEs are orally absorbed, leading to increased levels in the blood. Furthermore, in humans, increased MG and AGE levels in maternal blood correlate with increased MG and AGE levels in newborn blood, potentially exposing infants to high oxidative stress and inflammation. It is hypothesized that diet derived MG and AGEs in combination with inborn genetic vulnerabilities that affect the cellular redox status are major contributors to the development of autism and provide a causal link between oxidative stress, inflammation and mitochondrial dysfunction. If future research supports this hypothesis, then by reducing the exposure to these diet-derived factors, it might be possible to decrease the prevalence of at least a subset of autism cases.