Dopamine is a neurotransmitter associated with the pleasure centers of the brain. It is responsible for feelings related to love, joy, pleasure, reward and motivation. Serotonin is also a neurotransmitter and helps to regulate mood, irritability, impulse, obsession and memory.
Dopamine is the chemical in the brain that allows people to ride the highs of life. Any time a person has feelings associated with falling in love, experiencing great enjoyment or intense motivation, dopamine is at work in the brain. Depression caused by a chemical imbalance can be a result of insufficient dopamine in the brain. According to Dr. Ward Bond, doctors often do not check for this, and as a result many people are treated for a serotonin deficiency instead of a dopamine deficiency. Lack of dopamine in the brain causes feelings of low energy, depression and lack of motivation.
Serotonin is what helps humans to sleep, recharge, relax and generally cope with everyday life. A lack of serotonin may cause sleeplessness, a general feeling of emotional emptiness and paranoia or fear. Low levels of either neurotransmitter can cause severe personality and emotional changes in a person. This can result in a lack of ability to produce an emotional response and a limited ability to express remorse for actions.