Evidence that lithium protects against tardive dyskinesia: the Curaçao Extrapyramidal syndromes study VI.

Lithium may have neuroprotective properties and therefore could affect the occurrence of tardive dyskinesia (TD). We conducted a nine-year follow-up study with one baseline and six follow-up assessments including all psychiatric inpatients in Curaçao (N=194). TD was measured with the Abnormal Involuntary Movement Rating Scale (AIMS). There were 758 follow-up observations in the 166 patients (mean age 54.4 yrs, SD 16.0) with at least one follow-up assessment. Most patients (74%) had schizophrenia. The mean baseline score of the AIMS was 4.1 (SD 4.7). Sixteen patients (9.6%) used lithium at baseline and eight patients started lithium during follow-up. Prevalent and incident lithium significantly reduced the severity of existing TD with respectively 2.3 and 2.9 point reduction on the AIMS (AIMS score range: 0-23) and a standardised effect size of 0.5 for prevalent TD and 0.6 for incident TD. In the restricted sample of those with a baseline score of zero on the AIMS, prevalent lithium significantly lowered the risk of new abnormal movements (standardised effect size of 0.7). In conclusion, the use of lithium was significantly negatively associated with both persistence and onset of TD. These results suggest a beneficial effect on TD of lithium in some patients using long-term antipsychotics.