Those are the common symptoms, but MSUD can have other effects too. Someone named Nick Lovrin has had MSUD all his life, and he’s suffered some other symptoms. He said that it can affect almost anything you do. It can harm you mentally , because it becomes harder to understand basic information. Your brain starts to take longer to take it all in. It also makes it harder to be active because you use up energy so quickly. You’re not allowed to have many proteins, but you still need tons of calories.