ADHD is a genetic Neurodevelopmental Disorder

Attention-deficit/hyperactivity disorder, commonly known as ADHD, is a genetic condition. The study, funded by the Wellcome Trust is published in the latest issue of The Lancet. The researchers, from the Medical research council (MRC) center in Neuropsychiatric Genetics and Genomics and department of Psychological Medicine and Neurology, Cardiff University, Wales, UK, conclude that ADHD is a brain development disorder.

ADHD makes children fidgety, agitated, impulsive and easily distracted. Experts say that approximately 1 in 50 children is affected by ADHD. Although a number of factors have suggested genetics probably plays a major role, ADHD has frequently been attributed to a diet with too much sugar and poor upbringing.

Previous studies had shown that a parent with ADHD is more likely to have a child who also has a condition compared to parent without ADHD- a factor which points to some likely genetic association. If an identical twin has ADHD, there is a 75% chance that other twin will also have it.

The Authors explain that ADHD has no cure, but behavioral interventions and pharmacological therapy can help treat the symptoms.

The latest study, researchers analyzed the DNA of 336 children who had ADHD and 1,047 children who did not have the condition (controls).

The DNA analyses revealed that those with ADHD were more likely to have missing DNA segments, or segments of DNA that were duplicated compared to the controls. The authors explain that this kind of genetic variation is more widespread in brain disorders.

Thus the new study provides the first direct evidence that ADHD is a neurodevelopmental disorder.

Significant overlap was also detected between the segments, as well as those associated with schizophrenia and autism.

Although ADHD and autism are classed entirely separately, some overlap does exist between the two in terms of learning difficulties and symptoms. This study suggests there may also be some biological overlap between the two conditions, especially an overlap on chromosome 16 which had been implicated in schizophrenia and some other psychiatric disorders and spans a number of genes, including one know that is vital for brain development.

Professor Anita Thapar the Lead investigator said:

 Too often, people dismiss ADHD as being down to bad parenting or poor diet. As a clinician, it was clear that this was unlikely to be the case. Now we can say with confidence that ADHD is a genetic disease and that the brain of children with this condition develop differently to those of other children.

Doctor Nigel Williams said:

Children with ADHD have a significantly higher rate of missing or duplicated DNA segments compared to other children and we have seen a clear genetic link between these segments as other brain disorders. These findings give us tantalizing clues to the changes that can lead to ADHD.

Doctor Kate Langley explained:

ADHD is not caused by a single genetic change, but is likely caused by a number of genetic changes, including CNVs, interacting with as yet unidentified environmental factors. Screening children for the CNV’s that we have identified will not help diagnose their condition.

 A people with ADHD find it much more difficult to focus on something without being distracted.  They have greater difficulty in controlling what they are doing or saying and are less able to control how much physical activity is appropriate for a particular situation compared to somebody without ADHD, a person with ADHD is much more impulsive and restless.

Health care professionals may use any of the following terms when describing a child (or adult) who is overactive and has difficulty concentrating- attention deficit, attention feficit hyperactivity disorder, hyperkinetic disorder, hyperactivity.

ADHD in children is completely different from normal childhood exited and boisterous behavior. Many children, especially very young ones, are inattentive and restless without necessarily being affected by ADHD.

“Rare chromosomal deletions and duplications in attention- deficit hyperactivity disorder: a genome- wide analysis”

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 Ankit