Dopamine

Dopamine is a neurotransmitter (a chemical used to send signals between nerve cells) in the same family as epinephrine (adrenaline). Dopamine is one of the primary neurotransmitters and it affects motor functions (movement), emotions, learning, and behavior. It was originally identified as the brain chemical associated with pleasure. A decrease in the amount of dopamine in specific sections of the brain has been implicated as a possible cause of Parkinson's disease, while an excess of dopamine in some regions of the brain has been suggested as a possible cause of schizophrenia. Dopamine is also thought to play a role in depression, attention deficit hyperactivity disorder, high blood pressure, and drug addiction. Recently, dopamine has been used as a treatment for victims of heart attacks.

Since dopamine can increase blood pressure, it is used as a treatment for shock (low blood pressure throughout the body) which carries the risk of damage to major organs in patients who have suffered serious heart attacks. Dopamine raises the blood pressure and causes small blood vessels to constrict, thus raising the blood pressure throughout the body. Chemically related molecules such as adrenaline act similarly and both are often used to help patients.

Although individuals vary greatly in the amount of dopamine activity in their brains, in general dopamine appears to decline with age in those parts of the brain responsible for thinking. In particular, as people age, the number of dopamine D2 receptors decreases significantly. Thus, dopamine may be involved with the age-related loss of intellectual skills.