Amino Acid Profile Differentiation Detected Among Children With ADHD

Alterations in the amino acid profile of children with attention-deficit hyperactivity disorder (ADHD) were observed by investigators in a recent study published in Biomedical Reports. The results may support further research into potential new treatment strategies for ADHD, according to the investigators.

Generally, ADHD manifests in childhood, resulting in children diagnosed with the disorder having difficulty with concentration and issues around impulsivity. Additionally, ADHD is understood to manifest at the neurochemical level, such as by disrupting dopamine and norepinephrine pathways.

However, the amino acids in the brain that may cause these profile changes in children with ADHD is still not fully understood, despite most of the treatments for the disorder consisting of amino acids. Because of these lack of data on the exact amino acid profile that may lead to the positive response from common ADHD treatments among this population, the investigators looked to identify the alterations present in the amino acid profile in the blood serum of children with ADHD in comparison to neurotypical children.

"Amino acids serve a significant role in brain development and functioning. In particular, certain amino acids or their precursors are well-established to be involved in neuronal signaling as neurotransmitters,” said Anatoly Skalny, DSc, head of RUDN University’s Department of Medical Elements Studies—where the study was conducted—in a press release. “Correspondingly, disruption of amino acid metabolism results in significant neurological disorders, particularly in children. Therefore, unraveling the potential underlying mechanisms implicated in ADHD pathogenesis is essential for improving our understanding of the disorder and further development of management strategies."

During the study, the investigators included 102 children aged 7 to 14 years, 71 of whom had been diagnosed with ADHD and 31 of whom were neurotypical. Using liquid chromatography, the investigators assessed the levels of amino acids in the blood serum of the study participants. The investigators then compared the data from the children with ADHD to the neurotypical children using statistical methods.

The results from the study demonstrated that the amino acid profile in children with ADHD differed from that of neurotypical children, with histidine, glutamine, and proline levels found to be lower by 29%, 10%, and 20%, respectively. Conversely, aspartic acid and glutamate were found to be 7% higher, whereas hydroxyproline was 42% higher.

The investigators found based on these data, the ratio of glutamine to glutamate (Gln/Glu) among children with ADHD was 28% lower than it was among neurotypical children, whereas the ratio of proline to hydroxyproline was 29% lower. The Gln/Glu ratio is known to be one of the indicators of the transmission of nerve impulses, whereas the second ratio of proline to hydroxyproline (Pro/Hypro) is known as a marker of disorders of collagen metabolism and connective tissue.

“The observed alterations in Pro/Hypro and Gln/Glu levels and ratios are likely associated with the coexisting connective tissue pathology and alterations in glutamatergic neurotransmission in ADHD, respectively,” Skalny said in the press release. “However, further in vivo and in vitro studies are required in order to investigate the detailed mechanisms linking amino acid metabolism with ADHD.”

REFERENCE

RUDN University medics detect alterations in amino acid profiles in children with ADHD. Biomedical Reports; June 17, 2021. https://www.eurekalert.org/news-releases/797064. Accessed August 3, 2021.