People often argue whether depression is, or is not, caused by a "chemical imbalance". Much of what happens in our brains is chemical, why would depression not be? If by "imbalance" we happen to mean "a state of brain chemicals that the patient doesn't want", as opposed to, say, some specific theory that is now discredited like "not enough serotonin" (i.e., the low serotonin myth), then depression can reasonably be thought of as a "chemical imbalance". Disagreement about whether depressi...