25 to 28 is when the myelination of the brain finishes. https://www.sciencedirect.com/topics/medicine-and-dentistry/myelination https://www.sciencedirect.com/t

25 to 28 is when the myelination of the brain finishes. https://www.sciencedirect.com/topics/medicine-and-dentistry/myelination https://www.sciencedirect.com/topics/medicine-and-dentistry/... >Further myelination of subcortical and cortical tracts continues in the posterior to anterior direction well into the third decade of life, consistent with the time course of maturation of cognitive functions in children and adolescents. Mish Shoykhet, Robert S.B. Clark, in Pediatric Critical Care (Fourth Edition), 2011