The role of polyunsaturated fatty acids (PUFAs) in brain development and neurodevelopmental disorders is a relative new and challenging area of neurobiological research. PUFAs play a major role in the structure and function of the neuronal cell membranes in the brain. Recently, clinical trials have been conducted to supplement omega 3 PUFAs to patients with neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD), bipolar and schizophrenia. In contrast to ADHD, less is known about a possible role of PUFAs in the emergence of another major class of neurodevelopmental disorder, Autism Spectrum Disorders (ASD).
There is evidence to suggest that alterations to PUFA intake may impact on ASD diagnoses, with recent reports indicating that n-3 PUFA supplementation may reduce ASD symptomatology. However, it is clear, that more research is needed to strength the previous findings. Interestingly, mutations in genes (FABP 7, 5, 3) encoding how fatty acids bind and are absorbed within the body have been recently associated with ASD, reinforcing the impact PUFA's may have on the pathogenesis of ASD.
A recent review on ASD behaviour demonstrated that n-6/n-3 PUFA ratio disturbances during early life can affect major processes in brain development and induce aberrant behaviour. The way in which PUFAs impact neuronal development is thought to take place early in life through maternal depletion and/or early postnatal dietary changes (e.g. breastfeeding). It is the foregoing factors that appear to influence brain maturation and synaptic plasticity. In addition to changes in brain development processes, experimental PUFA ratio changes have been clearly shown to induce changes in behavioural expression, with changes mainly observed in the domains of anxiety, locomotor activity and learning and memory.
There is adequate research to show that children diagnosed with ASD have deficits in fatty acid levels, and preliminary data to support improved concentration, eye contact, language development and motor skill for autistic children administered n-3 PUFAs. However, it is thought that the rigorous change in dietary n-6/n-3 ratio, i.e. the introduction of vegetable oils and the removal of healthy forms of cholesterol, may be an important environmental factor in the increase of ASD related concerns. From a neurodevelopmental perspective, human studies indicate that the 3rd trimester of pregnancy and the first 6 months of life are the most important period for the uptake of n-3 PUFAs in the brain, of particular note, DHA. Targeting this critical window of opportunity with n-3 PUFAs may influence n-6/n-3 ratio and may positively alter the developmental trajectories of maladaptive behaviour and cognitive performance in individuals diagnosed with ASD.
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