A study carried out by Anne Halmøy, M.D., of University of Bergen, Norway and colleagues has found that children whose mothers are genetically predisposed to have impaired production of serotonin are more likely to develop ADHD later in life.

Serotonin is a hormone involved in the development of neurons, their migration to their proper position and the arrangement of the synapses between them. Serotonin is also important as a transmitter in the mature nervous system. Previous studies suggest that alterations in the genes or enzymes involved in the biosynthesis of serotonin in pregnant females could result in birth defects.

Six hundred and forty six individuals provided blood samples for gene sequencing and information about psychiatric diagnoses and symptoms. The researchers identified nine different mutations, of which eight were associated with impaired enzyme function. Analysis of 38 people who carried a mutation and 41 of their offspring showed that these offspring had a 1.5 – 2.5 higher risk of ADHD than either control individuals or children of fathers with the same mutations.

However there was a wide variance in the number and severity of symptoms reported, meaning that the outcome will depend upon many different genetic or environmental factors, and leading the researchers to conclude that although “maternal serotonin deficiency during pregnancy might predispose to neuropsychiatric disorders and cardiovascular illnesses”, further studies are required to substantiate these findings.

Source: published in the October 2010 issue of Archives of General Psychiatry, one of the JAMA/Archives journals.

This study was supported by the Research Council of Norway, Western Norway Regional Health Authority and the University of Bergen.

First published in October 2010

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