Dopamine is a chemical vital to your mental health. It is one of several types of neurotransmitters found in the brain, all of which help transmit brain signals from one cell to the next. Dopamine's specific functions also include controlling and influencing mood, as well as your brain's motor functions and information processing. Dopamine is released through various activities, such as sex, eating, taking illegal drugs and other activities--all of these activities can be addictive because of the reward dopamine provides. There are some influences that can cause dopamine levels to drop.
Drug Use
Some drugs create an addiction by overwhelming you with dopamine releases. This can create a sense of euphoria that can lead to addiction over time. Just as some drugs cause an overload of dopamine, others can actually restrict your brain's ability to enjoy dopamine. This happens when chemicals from a drug enter the brain and bind to the dopamine receptors in your brain without stimulating them, creating a blockage that prevent the dopamine chemical from attaching and stimulating your brain. According to the University of Texas, these drugs are called dopamine antagonists, and they can cause feelings of sadness and depression in some individuals because the dopamine is rendered unable to affect your mood. However, some individuals with illnesses that cause excessive dopamine activity--such as schizophrenia--can be treated with these drugs, which can curb the dopamine stimulation in their brain and help return them to normalcy.
Parkinson's Disease
Parkinson's disease is caused primarily by the degradation and breakdown of the neurons that release dopamine into your brain. Because dopamine plays a role in motor function, the gradual loss of dopamine can impair motor skills and motor function, causing tremors, trouble moving purposefully, slow movement and even paralysis in some muscles. According to a study conducted by MayoClinic.com and published by the American Academy of Neurology, a precursor to Parkinson's is an REM sleep disorder in which individuals kick and punch violently while sleeping. This is another demonstration of motor skill abnormalities that is likely related to dopamine levels.
Restless Legs Syndrome
Similar to how the REM sleep disorder may help predict Parkinson's disease, restless legs syndrome is considered a precursor to reduced dopamine production. Restless legs syndrome occurs when people move their legs aggressively while sleeping--this can occur several hundred times in one night. According to the National Institutes of Health, this syndrome can also lead to heart disease, in addition to a loss of dopamine.
