Children from poorer backgrounds are more likely to develop attention deficit hyperactivity disorder (ADHD), scientists have found.
A study by the University of Exeter Medical School discovered that a greater percentage of children with ADHD came from families below the poverty line than the UK population as a whole, with average family incomes for households whose study child was affected by ADHD at £324 per week, compared with £391 for those whose child was not.
The study found the odds of parents in social housing having a child with ADHD were roughly three times greater than for those who owned their own homes.
The team also found that the odds of younger mothers having a child with ADHD were significantly higher than for other mothers. Mothers with no qualifications were more than twice as likely to have a child with ADHD than those with degrees, and lone parents were more likely to have a child with ADHD diagnosis than households with two live-in parents.
Dr Ginny Russell, who led the study, said: "There is a genetic element to ADHD, but this study provides strong evidence that ADHD is also associated with a disadvantaged social and economic background.
"Some people believe that ADHD in children causes disadvantage to the economic situation of their family, but we found no evidence to support that theory. It's important to discover more about the causes of this disorder so that we can look towards prevention, and so that we can target treatment and support effectively."
Common symptoms of ADHD include inattentiveness, hyperactivity and impulsiveness. Symptoms tend to be first noticed at an early age and it is normally diagnosed between the ages of three and seven.
It is estimated the condition affects 2% to 5% of school-aged children and young people. However, it can be a lifelong condition and many children continue to show symptoms as a teenager and adult.
The Exeter team analysed data from the Millennium Cohort Study, a database of more than 19,500 UK children born between 2000 and 2002.
Information was gathered from surveys when the cohort children were nine months old, and at the ages of three, five, seven and 11.
The study, published in the Journal of Child Psychology and Psychiatry, was funded by the Economic Social Research Council's secondary data analysis initiative.
The findings support those of studies previously carried out in Northern Europe, the United States and Australia - but the findings show that the link between ADHD and socio-economic status exists in the UK.