Having a mother who suffered diabetes while pregnant and a poor social background both doubled the risk of attention deficit hyperactivity disorder. But the two factors combined boosted the chances of a child having the disorder by the age of six a massive 14 times.
Lead researcher Dr Yoko Nomura, from Queens College and Mount Sinai School of Medicine in New York, said: “To our knowledge, this is the first study to evaluate how prenatal exposure to gestational diabetes and low socio-economic status together contribute to the development of ADHD.”
“The results show these children are at far greater risk for developing ADHD or showing signs of impaired neurocognitive and behavioural development.”
Children with ADHD are typically hyperactive and impulsive. They may be easily distracted, restless, and have a short attention span.
Between 3 per cent and 9 per cent of children and young people in the UK are believed to be affected by the disorder. The US researchers evaluated a group of pre-school children using a standard ADHD rating scale and carried out tests of neuropsychological functioning, IQ and temperament.
Mothers were interviewed to see if they had a record of gestational diabetes mellitus (GDM), a version of the condition linked to pregnancy. Socio-economic status (SES) was evaluated with a recognised measuring tool called the socio-economic prestige index.
A total of 115 children with low SES, a mother with a history of gestational diabetes, or both, were compared with 97 who had neither.
The findings were published by the journal Archives of Paediatrics and Adolescent Medicine..
They showed that by the age of six, both gestational diabetes and low SES were separately associated with a doubling of ADHD risk. But the risk increased markedly – by 14 times – when the two factors were added together.
Children exposed to both gestational diabetes and low SES also had lower IQ, poorer language abilities and impaired behavioural and emotional functioning.
The scientists wrote: “This study demonstrates that children of mothers with GDM raised in lower SES households are at far greater risk for developing ADHD and showing signs of suboptimal neurocognitive and behavioural development.
“Since ADHD is a disorder with high heritability, efforts to prevent exposure to environmental risks through patient education may help to reduce the non-genetic modifiable risk for ADHD and other developmental problems.”
Two years ago the NHS in Scotland issued guidelines for treating the condition which included a recommendation that parents receive “behavioural training” to cope with affected children. The parental training was recommended by the Scottish Intercollegiate Guidelines Network, an organisation set up to examine the evidence for treatments and decide which should be provided by the NHS.