Hi, thanks for your question, and very interesting! Let me break this up into two parts: Regarding anxiety: Stress and anxiety lead to a production of adrenaline, which has a direct effect on the apocrine sweat glands. If more apocrine sweat is produced, this can lead to more body odor, when the bacteria convert these molecules into short chain and volatile molecules. Bacteria are also present in the hair follicles and sweat glands, where they convert sweat molecules into volatiles. When the adrenaline pushes out the apocrine sweat, this results in a burst of malodor.  Regarding ADHD & autism: there are studies that have shown differences in their gut microbiome. An altered gut epithelial structure and altered gut microbiome can impact the overall metabolism in the body and may lead to more sulfurous molecules in the sweat, which can result in oniony malodor. Also other factors can be of impact, such as diet, lifestyle and the use of medications.  It is difficult for me to formulate an answer to this problem, since it has so many different underlying aspects. I can however say that we've treated one person with autism with the probiotic spray, and the results were mind-blowing: from one of the most unpleasant smelling underarms to actual good smelling underarms. We'd like to repeat that experiment. Best, Chris