is a neurotransmitter, a chemical used to carry messages between
is produced in several areas of the brain, including the substantia
Dopamine's effects are complex and poorly
understood, but dopamine appears to play a role in signaling
reward in the brain. For example, "pleasurable" events such
as eating, drinking, and having sex are all associated with
increased brain dopamine levels, while individuals experiencing
depression or anxiety may have lowered brain dopamine levels.
Many drugs of abuse which give "pleasurable" or "calming"
highs, such as cocaine and nicotine, appear to work by mimicking
dopamine in the brain.
disease destroys dopamine-producing neurons in the substantia
nigra, and causes motor symptoms (dyskinesia,
as well as cognitive symptoms. The motor symptoms can be treated
by drugs that increase brain dopamine levels.
is a disorder associated with abnormally high levels of brain
dopamine; symptoms may include disordered thought, hallucinations
and social withdrawal. These symptoms may be ameliorated by
drugs that decrease brain dopamine levels.
Parkinson's patients given too much dopaminergic
medication may develop schizophrenia-like symptoms, while
schizophrenic patients given too much anti-dopaminergic medication
may develop motor problems reminiscent of Parkinson's disease.
Apparently, the brain requires a very delicate balance of
dopamine to function normally.
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain