Although opposite mood and psychomotor disturbances usually occur in
mania and
melancholia, clinical features may also be shared in common or may be present at the same time in both phases of
manic-depressive psychosis. In a parallel fashion, most pharmacological agents are selectively effective in one mood phase (tricyclics and
monoamine oxidase inhibitors for depression, and
neuroleptics for
mania) and frequently precipitate or exacerbate the opposite phase. These agents, therefore, may be affecting
biological substrates mediating the opposing phase of affective illness. With the exception of electroconvulsive therapy and
lithium chemotherapy, few treatments are effective in both
mania and
melancholia. It is noteworthy, therefore, that
carbamazepine may be useful in the acute and prophylactic treatment of
mania and
melancholia, including some
lithium non-responders and patients vulnerable to tricyclic-induced "mood switches". The clinical and
biological effects of
carbamazepine will be discussed with special emphasis on its biochemical action and the possible mechanisms by which it might influence
biological substrates mediating both phases of
manic-depressive illness. In addition, the theoretical implications of the presence of both shared and opposing clinical, pharmacological, and biochemical characteristics of the illness will be discussed.