Attention Deficit Hyperactivity Disorder (ADHD) is the commonest neurodevelopmental disorder of childhood, but its causes are largely unknown. Symptoms include inattention and forgetfulness, as well as hyperactivity and impulsiveness. More generally, sub-optimal cognitive development (difficulty processing thoughts, remembering, and problem solving) in childhood is associated with lower educational attainment and poorer life chances. There are clues that a poor diet in pregnancy may increase the risk of a child developing ADHD and cognitive difficulties, but the evidence is patchy and inconsistent, and sometimes based on small studies. Also, the role of childhood diet has been little studied, and we do not know whether effects of early nutrition on these conditions depend on genetic make-up.

We will investigate whether a poor diet in pregnancy and childhood is associated with a higher risk of developing ADHD and lower cognitive ability in childhood, and a healthier diet is associated with a lower risk, after allowing for background factors. We will also see whether effects of early diet and nutrition on risk of these conditions depends on the genetic make-up of the mother and/or the child. ALSPAC has all the data we need to investigate these hypotheses to a high standard. We are particularly interested in the role of healthy versus unhealthy dietary patterns, various foods (fruit, vegetables, oily fish), sugar, and specific nutrients including vitamins, folic acid, omega-3 fatty acids and choline. We will also analyse associations with blood vitamin D levels in pregnancy and childhood.