Link between ADHD and body clock established

A NUI Maynooth-based neuroscientist has helped establish a link between the genes that control our body clock and the common condition, attention deficit hyperactivity disorder (ADHD).

Dr Andrew Coogan’s research found the genes which control our circadian rhythm do not function properly in adults with ADHD, a condition characterised by inattention, hyperactivity and hyper-pulsivity.

The research opens the possibility of using existing treatment such as light therapy to deal with a condition which affects 5-7 per cent of children and 3-5 per cent of adults. It is normally treated with the drug Ritalin.

“It has been shown in other conditions such as depression that if you find that an individual has depression and has an abnormal circadian rhythm, by putting the ciracdian rhythm back to its correct time, you can improve depressive symptoms,” he said.

“We’re interested in finding out if this is the case with ADHD.”

It also corroborates established research that sleep patterns for people with ADHD are much poorer than the rest of the population.

DNA samples were extracted from 13 ADHD patients and a control group of 23 people at the University of Swansea.

The genes that control the circadian rhythms were extracted from cheek swabs taken from both groups and analysed. They were taken at regular intervals for a week and each participant in the trial wore an Actiwatch which determined their activity and sleeping patterns.

When a gene is switched on, it undergoes a process called transcription, where DNA is converted into RNA. That RNA is then translated into protein. Because it is possible to detect RNA in saliva, they could ascertain which genes were switched on or off.

“We noted healthy patients showed body clock genes that were switched on at appropriate times of the day whereas the ADHD patients exhibited body clock genes that were flat with little, or no, activity,” said Dr Coogan, adding that the disruption of circadian rhythms in adults with ADHD seemed to get more pronounced with the worsening of ADHD symptoms.

Though the research pertained to adults, Dr Coogan, who specialises in research into circadian rhythms, said it was also applicable to children as well where the condition was much better known and was associated mostly with hyperactivity and in an inability to concentrate.

He stressed the condition was often accompanied by other “core morbidities” and associated psychiatric disorders including depression and substance abuse.

“You’ll practically never find an adult with ADHD who just has ADHD,” he explained. It is also much more prevalent in the prison population.

The research was published in the journal Molecular Psychiatry, part of the Nature Group.