DURING an investigational new drug study of lithium ion in manic-depressive illness and recurrent depressive disorders we have encountered certain observations which have highlighted the problems of the differential diagnosis of mania and led us to consider a therapeutic trial of lithium carbonate in certain cases when the diagnosis is in doubt.
It has been noted that between 15% and 25% of manic-depressive patients may have hallucinations of delusions1,2 and that in such cases confusion with schizophrenic illness can and does occur. Delusions are not uncommon, but hallucinations are considered rare except in so-called "delirious mania.''3,4 Acute manic episodes may be mistaken for acute paranoid reactions, especially when instead of manic exaltation the manic person breaks out with hostile aggression, becomes haughty, and complains wildly about the way he is treated.5 A well-developed paranoid trend may exist.6 In a