Dopamine is a neurotransmitter, and it affects the brain processes that control emotional responses, movement and your ability to feel pleasure and pain. Regulation of dopamine levels plays a critical role in physical and mental health.

Parkinson's disease causes the brain to lose neurons that include dopamine. The brain of a person suffering from Parkinson's disease produces little to no dopamine.

Using drugs such as ecstasy, cocaine and amphetamines destroys the receptors that control the production of dopamine. These drugs, when ingested, cause an excess amount of dopamine to be released, which depletes the amount of dopamine available for assigned tasks.

Viral infections that attack certain parts of the brain can cause low levels of dopamine. If the infection attacks the part of the brain that contains the dopamine receptors, the person could suffer symptoms similar to Parkinson's disease.

Restless leg syndrome is a condition that affects movement, which is regulated by dopamine. People who suffer from restless leg syndrome may have a dopamine deficiency.

Dopamine can be replenished by activities such as exercise. Challenging environments such as the classroom, social interactions and physical activity are thought to encourage the development of brain cells and neurotransmitters such as dopamine.