Neuroleptic medication facilitates the natural occurrence of tardive dyskinesia. A critical review.

The literature concerning the connection between Tardive Dyskinesia (TD) and the chronic use of neuroleptics is reviewed. On the average, three times more TD's can be observed in a population treated chronically with neuroleptics (about 20%) than in untreated groups (5-9%). Various analyses do not justify the contention that one neuroleptic or group of neuroleptics would elicit more TD's than another one. Questions about the mechanisms by which TD is brought about remain unanswered. More attention is now being paid to brain function and age. Possible changes in the sensitivity of the dopamine receptor are no longer being regarded as a primary mechanism. A working hypothesis is proposed according to which TD would be induced by various adaptation mechanisms in the brain, which also points to a possible explanation of the reversibility of TD. It is now accepted that TD symptoms can disappear or improve greatly in about 60% of patients during the course of 2-3 years, which reduces the group of irreversible TD's to the number of spontaneously occurring dyskinesias.