The autistic brain is quite often under a combination of metabolic stress, oxidative stress, and nutritional deficiency. Some autistics do have difficulties in what is known as methylation.
1. When given the choice, pick methyl-B12,...not B12,...and methyl-folate,...not folate. Both of which have been tested in autistics.
2. Pick anti-oxidant supplements that cross the blood-brain barrier,...specifically, resveratrol, ubiquinol, and N-acetyl cysteine. All of which have been studied in autistics.
3. Broad-spectrum probiotics,...the more species and higher the concentration, the better. Read up on the gut-brain axis as it pertains to autism, neurotransmitter balance, and symptomatology.
4. Melatonin, chelated magnesium, and L-theanine for better sleep and relaxation.
5. Minimize your carbohydrate intake as many carbs are "pro-inflammatory" and stimulate excess insulin, which influences brain function. Read up on autism diet plans.
Do a Google Scholar or PubMed search on these topics. Given the highly variable epigenetics found within the autistic population,...some things are going to work better than others. Furthermore, if you are on any medications, check for interactions before spending your money on supplements.
Take care of your brain. I cannot emphasize this enough,...the autistic brain takes some extra care and consideration,...no different than anyone else with a heart, kidney, liver, pancreatic issue, and so on. Although some would like to pass off autism as some form of neurodiversity, or some primarily psychological condition,...it's a lot more than that,...it also has a physiological/medical component, as well. Take care of yourself.