Carnosine has shown some improvements in cognitive outcomes in autism (Chez et al, 2002) and schizophrenia (Chengappa et al; unpublished). Chez used oral doses of 800mg/d for 8 weeks; while the latter study used oral doses of 2000mg for 4 weeks showing positive effects. Hence this is the dose and delivery route that will be used. The investigators have opted for 4 weeks course following broadly from these two studies. Carnosine is widely available from health and food supplement shops in the UK and US retail market in highly pure form; is a naturally occurring in food and the human body; and is well-tolerated and has a benign side-effect profile, as shown from previous trials, and is therefore not associated with any potential risks.