Affective symptomatology in schizophrenia: a risk factor for tardive dyskinesia?

Epidemiology of tardive dyskinesia before and during the era of modern antipsychotic drugs

Late or tardive dyskinesias/dystonias (TD), contrary to expectation, have not disappeared with the use of expensive, modern antipsychotic drugs (APDs). Risk appears to be substantially lower than with older neuroleptics, and there is sparing of most acute movement disorders traditionally associated with APD treatment. However, risks of TD with modern APDs have been reduced much less than expected, by perhaps two- to threefold or even less, with substantial risks in the elderly. Major challenges in assessing prevalence or, preferably, incidence of TD arise from prolonged and erratic past exposure to various APDs, relatively recent use of modern APDs, and the occurrence of spontaneous movement disorders (about 5% and more in the elderly). TD risks associated with modern APDs may be similar to some older neuroleptics, especially those of low-moderate potency. Risperidone (and its active metabolite paliperidone), at high doses, may carry unusually high TD risk, whereas TD risk is low with clozapine, and perhaps quetiapine and aripiprazole. Optimistic expectations for the efficacy and neurological safety of modern APDs have encouraged their wide use in many conditions, sometimes off-label or in combinations, with little research support, increasing the chance of a higher prevalence of TD, especially at older ages. Measures to limit TD risk include: (1) critical, objective indications for APD use; (2) long-term use only for compelling or research-supported indications, primarily chronic psychotic illness that worsens when APD is slowly discontinued; (3) avoiding off-label indications; (4) using alternative treatments when APD treatment is elective, or early dyskinesia is identified; (5) using low but effective doses of single APDs, especially in the elderly; and (6) regular and specific examination for early TD.

Epidemiology of tardive dyskinesia: Is risk declining with modern antipsychotics?

Second-generation antipsychotic drugs (APDs), including aripiprazole, clozapine, olanzapine, risperidone, quetiapine, and ziprasidone dominate outpatient and inpatient clinical practice, having largely displaced the older neuroleptics. Modern APDs have relatively low risk for acute extrapyramidal syndromes characteristic of older neuroleptics, particularly acute dystonia and Parkinsonism, with variable risks of akathisia and the rare neuroleptic malignant syndrome. Anticipated reduction in risk of tardive dyskinesia (TD) is less well documented. Nearly 50 years after initial reports on TD, it is appropriate to reexamine the epidemiology of this potentially severe late adverse effect of long-term APD treatment in light of current research and practice. We compared recent estimates of incidence and prevalence of TD identified with some modern APDs to the epidemiology of TD in the earlier neuroleptic era. Such comparisons are confounded by complex modern APD regimens, uncommon exposure limited to a single modern APD, effects of previous exposure to typical neuroleptics, and neurological assessments that are rarely prospective or systematic. Available evidence suggests that the risk of TD may be declining, but longitudinal studies of patients never treated with traditional neuroleptics and exposed to only a single modern APD are required to quantify TD risks with specific drugs. Long-term use of APDs should continue to be based on research-supported indications, with regular specific examination for emerging TD.

Pharmacogenetics in affective disorders

Pharmacogenetics will be of substantial help in the field of affective disorders pharmacotherapy. The possible definition of a genetic liability profile for drug side-effects and efficacy will be of great help in treatments that need weeks to months to be effective. During the last few years, a number of groups have reported possible liability genes. The efficacy and time of onset of selective serotonin reuptake inhibitors have been associated with a polymorphism in the promoter region of the transporter (SERTPR) in many independent studies, while variants at the tryptophan hydroxylase gene, 5-HT2a receptor and G-protein beta3 have been associated with them in pilot studies. Lithium long-term prophylactic efficacy has been associated with SERTPR, TPH and inositol polyphosphate 1-phosphatase variants, though in unreplicated samples. A number of further candidate genes were not associated with these treatments. In conclusion, both acute and long-term treatments appear to be, at least to some extent, under genetic influence and preliminary data have identified possible liability genes.