The significance of subtyping tardive dyskinesia: a study of prevalence and associated factors.

The prevalence of tardive dyskinesia (TD) in 137 Nigerian psychiatric patients was 27%. There were no differences in the prevalence rate between patients with affective disorder and those with schizophrenia. There were also no significant differences between the sexes but a trend for the more severe forms of dyskinesia to be commoner in females was noticed. Demographic, clinical and treatment variables were investigated for association with TD and each of its two putative subsyndromes: orofacial and appendicular dyskinesias. Two cases of severe and persistent tardive dystonia, associated with orofacial TD, were seen in two young adults, one with relatively short exposure to neuroleptics. After initial univariate screening, multivariate statistical methods revealed that different factors were associated with each of the two subsyndromes. While length of hospitalization correlated significantly with orofacial dyskinesia, cumulative duration of exposure to high-potency neuroleptics and number of ECTs received were significantly associated with appendicular TD. Neither age nor sex correlated with either of the subsyndromes. The findings confirm and extend previous observations suggesting that these dyskinesias may involve different pathophysiological mechanisms.