What is ADHD?

ADHD affects how the brain regulates attention, activity and self-control, and it is estimated to affect roughly 5 to 7 percent of children and about 2.5 to 3 percent of adults worldwide. It is strongly genetic, with twin studies suggesting heritability of around 70 to 80 percent, and it involves differences in brain signalling chemicals such as dopamine and noradrenaline. A 2007 brain-imaging study found that parts of the cortex matured about three years later on average in children with ADHD. The condition was first described by British paediatrician Sir George Still in 1902, and the name ADHD entered the diagnostic manual in 1987. Treatment usually combines behavioural strategies and support with medication such as stimulants.