There is little scientific evidence to support the idea that certain psychiatric disorders and cognitive traits are linked to brain structure. Studies have been limited to adults only. The question remains unanswered. A study by the Barcelona Institute for Global Health, a centre supported “la Caixa”, that analysed data from large paediatric samples has provided new evidence.
The study was published in the Journal of the American Academy of Child & Adolescent PsychiatryWe analysed data from 1,139 boys/girls aged 10 years from the Dutch Generation R Study. The authors calculated each participant’s genetic susceptibility to five mental disorders and two cognitive traits using polygenic risk scores that were based on genetic data. The most recent results of genome-wide association studies, which included thousands of participants, were used to calculate the polygenic scores. To test for associations between polygenic risk scores, magnetic resonance brain imaging results, and the polygenic risk score, regression analysis was used. The results showed a tendency for total brain volume to be greater in children with higher polygenic scores relating to intelligence or educational attainment.
Participants with higher polygenic risk of attention-deficit/hyperactivity disorder (ADHD) had a smaller volume of the caudate nuclear, which is one of the structures that makes up the brain. Silvia Alemany from ISGlobal, the lead author of this study, says: “This finding was significant because, although ADHD and a smaller caudate nuclear volume is now considered a consistent finding but the mechanism behind it is still poorly understood. The association could be explained by genetic variants associated with ADHD, as we found in this study.
The analysis revealed that morphological differences in caudate nucleus may partially explain the association between ADHD and attention problems in boys. However, this association was not seen in girls. Silvia Alemany explains that ADHD is more common in boys than in girls. The reasons for this difference are still being explored. “Our findings suggest that ADHD genes may be different in boys and girls.”
Five psychiatric disorders were included in the polygenic risk calculation: ADHD, autism spectrum disorder, schizophrenia, bipolar disorder and major depression. ADHD was the only condition that was significantly associated with brain volume.
The study was based only on data collected at a single point in the participants’ lives, according to the lead author. “More research is required to measure the brain over time in order to determine if the polygenic risk of psychiatric disorders and cognitive traits is related with changes in developmental trajectories.”
Materials provided by Barcelona Institute for Global Health, (ISGlobal).. Note: Content may be edited to improve style and length.