Gut microbiome in ADHD and its relation to neural reward anticipationOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
Researchers compared the gut microbiome of 19 adolescents and adults with ADHD against 77 controls. They tested whether microbiome differences related to neural reward processing, a core deficit in ADHD.
How was it studied?
16S rRNA gene sequencing identified bacterial taxa and predicted gene functions in stool samples. A subset of 28 participants also underwent fMRI during a reward-anticipation task, independent of diagnosis.
What did they find?
Bifidobacterium relative abundance rose from about 12.7 percent in controls to 20.5 percent in ADHD cases (p = 0.002, uncorrected). This tracked with roughly 150 percent higher predicted abundance of cyclohexadienyl dehydratase, an enzyme that synthesizes phenylalanine, a dopamine precursor, in ADHD cases (p = 0.038, corrected). Higher predicted enzyme abundance was associated with lower ventral striatal fMRI responses during reward anticipation, independent of diagnosis and age (beta = -0.48, p = 0.032).
Why it matters
Blunted ventral striatal reward anticipation is a neural hallmark of ADHD. This pilot study proposes a gut-microbiome pathway, via dopamine precursor synthesis, that could contribute to that deficit.