The effect of atypical versus typical antipsychotics on tardive dyskinesia: a naturalistic study

The aim was testing whether atypical antipsychotics (versus typicals) were associated with less risk of tardive dyskinesia (TD) in 516 severely mentally ill patients.

The sample included 11% (57/516) with no exposure before current treatment with atypicals; 9% (48/516) with prior and current treatment with atypicals but no exposure to typicals; 18% (94/516) with lifetime exposure to typicals for <5 years (plus atypicals); and 62% (317/516) with lifetime exposure to typicals for >or=5 years (plus atypicals). The Abnormal Involuntary Movement Scale (AIMS) was used to assess dyskinetic movements. Following Schooler and Kane's criteria TD was considered present when mild movements were present in at least two body areas or moderate movements were present in at least one body area.

TD prevalences were 5% (3/57) in previously naïve patients, 19% (9/48) after exposure only to atypicals, 19% (18/94) after typical exposure of <5 years, and 42% (132/317) after typical exposure of >or=5 years. There was no significant effect comparing those taking only atypicals to those exposed to typicals for <5 years (OR = 1.0, CI 0.42-2.5).

This study is limited by the naturalistic design, the relatively small samples in the first two groups, the lack of information on the duration of the atypicals and their relatively recent introduction to the market (ziprasidone and aripiprazole were introduced to the market in the middle of the study). This study raises the question that new TD studies need to establish whether decades of treatment with atypical antipsychotics make a difference.