Historical perspectives on tardive dyskinesia

Tardive dyskinesia (TD) is a persistent hyperkinetic movement disorder associated with dopamine receptor blocking agents including antipsychotic medications. Although uncertainty and concern about this drug side effect have vacillated since its initial recognition 60 years ago, recent commercial interest in developing effective treatments has rekindled scientific and clinical interest after a protracted period of neglect. Although substantial research has advanced knowledge of the clinical features and epidemiology of TD, many fundamental questions raised by early investigators remain unresolved. In this paper, we review the early clinical reports that led to the acceptance of TD as an iatrogenic disorder and the lingering controversies that emerged thereafter. Continued research on TD as a serious adverse reaction to treatment may not only enhance patient outcomes and recovery efforts but may also provide insights into both the mechanism of action of antipsychotic drugs and the nosology and pathophysiology of idiopathic psychomotor disorders.

Instrumental measurements of spontaneous dyskinesia and schizotypy in subjects with auditory verbal hallucinations and healthy controls

Spontaneous dyskinesia is associated with non-affective psychosis. Few studies investigated dyskinesia in individuals with subclinical psychotic experiences. We examined dyskinesia using instrumental measurements of force variability in 34 individuals with frequent auditory verbal hallucinations but without a clinical psychotic disorder and 31 matched healthy controls. Schizotypy was assessed using the Schizotypal Personality Questionnaire. We found a positive correlation between dyskinesia and schizotypy in the total group. In addition, when using a cut-off point based on the 95th percentile of force variability in the control group, we found a greater proportion of subjects with dyskinesia in the group with auditory verbal hallucinations than in the control subjects. Current findings are in agreement with the concept of psychosis as a continuous phenomenon and with movement disorders being an integral part of psychosis.

Striatal abnormalities and spontaneous dyskinesias in non-clinical psychosis

BACKGROUND

Accumulating evidence suggests that individuals experiencing non-clinical psychosis (NCP) represent a critical group for improving understanding of etiological factors underlying the broader psychosis continuum. Although a wealth of evidence supports widespread neural dysfunction in formal psychosis, there has been little empirical evidence to inform our understanding of putative vulnerability markers or brain structure in NCP. In this study, we examined the neural correlates of spontaneous movement abnormalities, a biomarker previously detected in NCP that is linked to abnormalities in the striatal dopamine.

METHODS

We screened a total of 1285 adolescents/young adults, and those scoring in the upper 15th percentile on a NCP scale were invited to participate; 20 of those invited agreed and these individuals were matched with healthy controls. Participants were administered a structural scan, clinical interviews, and an instrumental motor assessment.

RESULTS

The NCP group showed elevated force variability and smaller putamen (but not caudate), and there was a significant relationship between motor dysfunction and striatal abnormalities for the sample. Elevated force variability was associated with both higher positive and negative symptoms, and there was a strong trend (p=.06) to suggest that smaller left putamen volumes were associated with elevated positive symptoms.

CONCLUSIONS

The results are among the first to suggest an association between neural structure and a risk marker in NCP. Findings indicate that vulnerabilities seen in schizophrenia also characterize the lower end of the psychosis spectrum.