Physiologists, psychologists, and pharmacologists seem to agree that one of the main causes of depression mood involves chemical imbalance. The neurotransmitters involved are Serotonin, Dopamine, and norepinephrine (noradrenaline). The effect of each on different brain areas was discussed, as well as the main psychological affects. A Venn diagram was used to show that they all work together in producing "mood", and that a lack of one or more, can lead to anxiety or depression. Serotonin was used to describe how the specific binding to receptors allowed for the stimulation of areas of the brain which are involved with pleasure and happiness. The normal destruction of serotonin by specific enzymes secreted into the synapse will cause a decrease or halting of the "happy" mood. How selective serotonin re-uptake inhibitors work to decrease the destructive enzymes of serotonin and prolong the effects of serotonin and dopamine was discussed.