A second generation catecholamine hypothesis.

The catecholamine hypothesis proposed an increase in functional brain norepinephrine in the manic phase of manic-depressive illness. This paper reviews a secondary hypothesis suggesting that dopamine may be involved in the manic process. Increases in functional dopamine may result from the release of dopamine which is amplified by a supersensitive dopamine receptor that has developed during the depressive phase prior to the onset of mania. Lithium may act, in part, by blocking the development of supersensitive dopamine receptors. Evidence compatible with this hypothesis is reviewed.