I was watching a documentary about the barbaric tribes from ancient Rome. They were discussing how the Huns would alter the shape of their skulls with leather straps. Do we know how this affect their brain development?
A different-shaped skull will result in a somewhat different-shaped brain, but we have no evidence of any harmful neurological or psychological effects. See the answer by u/Libertat and myself in https://www.reddit.com/r/AskHistorians/comments/bdchtv/did_the_huns_actually_practice_ritual_cranial/ (including cranial reshaping in Medieval and modern Europe into the 19th century). If you want more on the lack of evidence of harmful effects, see Molnár (2014) cited in my answer.