Changes in negative symptoms and the risk of tardive dyskinesia: a longitudinal study

Abstract

To examine whether the development of tardive dyskinesia (TD) is accompanied by a parallel process of worsening negative symptoms in a longitudinal study. A sample of 708 psychotic patients were followed over a period of 2 years, using the Abnormal Involuntary Movement Scale and the Scale for the Assessment of Negative Symptoms (SANS). Of 361 individuals with no prior evidence of dyskinesia, 46 (13%) developed TD by year 2. Independent of the effects of male sex (odds ratio (OR)=2.18, 95% confidence interval: 1.00-4.74), age (OR per quartile group = 1.39, 95% CI: 1.01-1.90), duration of exposure to antipsychotic medication (OR = 2.35 per 8 months, 95% CI: 1.17-4.72) and average SANS score (OR per quartile group = 1.38, 95% CI: 0.99-1.93), worsening of negative symptoms over the 2 previous years was associated with TD onset (OR per quartile group = 1.46, 95% CI: 1.07-2.00). The development of TD is linked, independent of the effect of antipsychotics and older age, to an illness-related pathological process, characterized by worsening negative symptoms.