University of Nottingham's Stephen Jackson, who examined brain scans of people with Tourettes, says: "'The motor outputs of children with Tourettes syndrome are under greater cognitive control. You might view this as their being less likely to respond without thinking, or as being less reflexive.' This helps explain why some people may have many tics as children, but as adults have very few. Over time, their brains have developed ways to control these tics. Jackson points out that this may mean people with Tourettes need mental exercises rather than brain surgery or drugs, because their brains will naturally develop compensatory mechanisms.