Question: Can MTHFR cause ADHD?So, methylation will reduce the background level of tonic dopamine. And make you more mentally flexible. And a lack of methylation will generally lead to a higher level of background dopamine and make you not as mentally flexible. So, I really don't think that the ADHD is solely a consequence of MTHFR. Low methylation state and glycine wasting is probably playing into some of the aggravating factors, particularly glycine wasting. If you would like to be part of the next live Ask Me Anything About Nutrition, sign up for the CMJ Masterpass, which includes access to these live Zoom sessions, a private discussion group, premium features on all my content, and hundreds of dollars of exclusive discounts. You can sign up at https://chrismasterjohnphd.com/masterpass/ and use the code QANDA to get 10% off the membership for life. From now through March, I will be working full-time on finishing my Vitamins and Minerals 101 book, while reserving a portion of my time for consulting clients. You can pre-order my book at https://chrismasterjohnphd.com/book. You can sign up for a consultation at https://chrismasterjohnphd.com/consultations. DISCLAIMER: I have a PhD in Nutritional Sciences and my expertise is in performing and evaluating nutritional research. I am not a medical doctor and nothing herein is medical advice.