ADHD could cause lower dopamine functioning

Adults with attention deficit/hyperactivity disorder (ADHD) show a blunted response to the drug methylphenidate (Ritalin), which increases brain dopamine levels, according to a new study. This finding suggests that dopamine dysfunction may be involved with ADHD symptoms and may contribute to substance abuse that often occurs simultaneously. In the study, doctors investigated 19 adults with ADHD whose average age was 32 and who had never received medication and compared them to 24 healthy controls whose average age was 30. {openx:269} Brain scans were performed twice, after injections of placebo and of methylphenidate; the participants did not know which drug they…