Serotonin: a common neurobiologic substrate in anxiety and depression.

Anxiety and depression have traditionally been considered independent pathologies. Recent evidence suggests that these disorders may be related. Some tricyclic antidepressant drugs appear to be effective against generalized anxiety disorders in man, and in animal models, chronic administration of some anxiolytic drugs produces activities predictive of antidepressant potential. It is proposed that imbalances in serotonergic neurotransmission may contribute significantly to both pathologies and that agents that act as serotonin partial agonists may normalize neurotransmission in both serotonin deficit (depression) and excess (anxiety) diseases. The azapirones, a new class of drugs that includes buspirone, ipsapirone, and gepirone, act as serotonin partial agonists at the serotonergic type1A receptor, and may prove useful in treating multiple psychopathologies characterized by aberrant serotonin neurotransmission.