Dopamine is a naturally occurring chemical transmitter in the brain. It has a number of functions, including controlling the body’s movements and helping to regulate mood. Negative consequences result from having too much or too little dopamine. People can take synthetic dopamine as a prescribed medication or as an illicit drug and, in these cases, the effects of dopamine often are pronounced.
In a normal brain, certain cells release dopamine when the person experiences something pleasurable, such as when enjoying a meal, driving really fast or going for a jog. This dopamine production helps to regulate emotions. People will repeat actions when they receive the good feelings from dopamine. This dopamine “high” can encourage people to continue making good decisions, such as exercising, or bad ones, such as using drugs.
Another benefit of typical dopamine production is to help control the body’s movement. The effects of dopamine in too small of an amount include an inability to move all of one’s body properly and an inability to control one’s movements. People with Parkinson’s disease have depleted dopamine receptors, resulting in shaky movements. With too much dopamine, people have the opposite problem. They are twitchy and often have repetitive, unconscious movements.
Dopamine also can control a person’s energy levels. This chemical increases the body’s metabolism, which can increase energy levels. Increased metabolism can result in weight loss as a person's body burns calories more quickly. Dopamine fills the synapses, which are open areas in the brain. A lack of dopamine can lead one to feel sluggish and groggy; this low level of dopamine is the source of the saying "the synapses aren't firing" or that someone is not "firing on all cylinders."
Some prescription medications are synthetic dopamine, or chemicals with a very similar composition to natural dopamine and which act the same way in the brain. These medications often are used to treat mental illnesses, including severe forms of bipolar disorder. People who need dopamine do not have enough of the hormone, which can increase the incidence of depression because of the relationship between decreased dopamine levels and depression.
Few studies exist on the range of side effects of dopamine when there is too much synthetic dopamine in the body. Cardiac arrhythmia, or an irregular heartbeat, is one of the common effects of excess dopamine. Other side effects of dopamine include heart pain and high blood pressure. These side effects can be dangerous, and anyone with these problems should see a medical provider immediately.