Dyskinesia, antipsychotic-drug exposure and risk factors in a developmentally-disabled population.

The relation between antipsychotic drug (APD) exposure and the prevalence of dyskinesia (DK) was examined in a large, developmentally-disabled (DD) population. Using qualitative data in a cross-sectional, retrospective design, the drug-exposed group was systematically compared with a non-drug-exposed group, controlling for age and gender. When the population was evaluated with no regard to APD-exposure, age and female gender were significant risk factors, as in many prior studies. When APD-exposure was considered, it proved to be a complex variable dependent on the recency of exposure to APD, and the outcome depended on the method of analysis: when APD-exposure was considered as a binomial variable (yes/no), the relationship between APD and DK was not significant; when APD-exposure was controlled for recency of exposure, however, a significant relationship between APD and DK was demonstrated (p less than 0.01) although the relationship accounted for less than 3% of the variance. Analysis of the relation between DK-prevalence and recency-of-APD-exposure revealed a pattern of diminished prevalence during APD use and increased prevalence during early withdrawal.