Psychotic depression: the common therapeutic principle.

Cholinergic prevalence together with a monaminergic deficit characterize the neurotransmitter imbalance underlying psychotic depression. Correction of this neurotransmitter imbalance is the principal purpose and goal of all treatment methods for the relief of psychotic depression. This can be accomplished by reducing the acetylcholine predominance or increasing the level of monaminergic functioning, or a combination of both approaches. The antidepressant tricyclic drugs combine a central anticholinergic action with an aminergic potentiating function. Electroconvulsive therapy is effective through activation of both cholinergic and aminergic systems, with removal of excess acetylcholine into the cerebrospinal fluid. Psychiatric surgery restores neurotransmitter balance by blocking excessive acetylcholine synthesis and activity.