Four different studies done in the past decade using MRI (magnetic resonance imaging) all found aslight reduction in the size of four regions of the brain: the corpus callosum, the basal ganglia, the frontal lobes, and the cerebellar vermis.
Stand-up comic Tony Jameson, who has an occasional, slight stammer, says that if a comedian has a structure and a routine that includes someone who speaks in adifferent way, it can be sometimes be acceptable.