There is some debate concerning the causes of depression. On the one hand, it is considered a physiological disorder of the brain. Signals are sent through the brain–and in fact the entire nervous system–by special chemicals calledneurotransmitters. There are many of these, but the ones which seem to have the greatest impact on a person’s mood are serotonin, norepinephrine, and dopamine. Depression appears to involve a reduced amount of one or more of these, hindering brain signals and in turn causing the various symptoms of depression. MRI’s and brain tissue samples of depressed patients shows that these neurotransmitters are below normal.

While this is true, however, there are usually circumstantial influences as well. Depression almost always follows some upsetting or terrible event in someone’s life (it can come immediately or after some length of time). Cases in which people become depressed solely…