Critical flicker fusion (CFF) has had widespread usage in studying the older physiological treatments in psychiatry such as brain surgery, insulin coma and electroeonvulsive therapies (DILLon). More recently CFF has been singled out as one of the most sensitive indices of psychotropic drug effect (LEHMAN~ and CSANK; LEHMANN and KNIGHT).
This study of CFF threshold is part of a larger investigation concerned with the effects of chlorpromazine, imipramine and placebo on physiological, psychological and psychiatric aspects of behavior (F~K et al.).
In reviewing the literature on CFF and drugs in man, we have noted three systematic studies of chlorpromazine and none of imipramine. In normals a single dose of 100 to 150 rags of chlorpromazine produced a significant decresae in CFF, whereas placebo did not alter the threshold (L~HMA~N and CSANK). In contrast a maintenance dosage of 100 mg daily for thirty days given to a group of psychiatric patients did not significantly lower CFF (RosN~ et al.). LORA~G~ employing a daily dosage of between 200 and 400 mg in psychiatric patients for a similar period found that the CFF change was significant for only one of six testing conditions.
The discrepancy in findings between the studies of chronic administration in psychiatric patients and the single dose in normals may be due to the drug tolerance developed with continued usage.
A number of studies (Ko~N~TS~ZY; D~MAscIo et al.) have demonstrated that psychological test changes with chlorpromazine were dosagerelated. It is possible that with chronic administration of higher dosages in psychiatric populations a decrement similar to that obtained following acute administration in normals will be found.