MONDAY, Oct. 4 (HealthDay News) -- Children whose mothers are likely to produce too little of the brain chemical serotonin because of gene mutations may be at higher risk of developing attention-deficit hyperactivity disorder (ADHD) later in life, Norwegian researchers report.
Serotonin is involved in many physiological functions and plays an important role during development, especially in the development of nerve cells, the researchers say.
"An impaired maternal serotonin production may have profound long-term behavioral effects on [offspring], independent of the children's own genotypes," said lead researcher Dr. Jan Haavik, from the Department of Biomedicine at the University of Bergen.
"As technologies evolve, systematic gene sequencing can provide new insight into mechanisms of complex disorders like ADHD," he added.
The report is published in the October issue of the Archives of General Psychiatry.
For the study, Haavik and colleagues took blood samples from 495 adults with ADHD and 97 of their family members as well as from 187 people without ADHD from across Norway. In addition, they collected data on these individuals' psychiatric diagnoses and symptoms.
The researchers then sequenced the genes of 646 of the participants and found nine mutations, eight of which were linked to the two enzymes involved in the body's synthesis of serotonin.
The researchers found that children of mothers who were predisposed to impaired serotonin production were more likely to have ADHD. Among 38 family members and 41 of the children, those whose mother had one of the mutations had a 1.5 to 2.5 higher risk of developing ADHD, compared with people or children who did not have these mutations or children whose father had the mutations.
The number and severity of ADHD symptoms varied widely, which suggested that for children of mothers with
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