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The effects of antipsychotic medication on saccadic eye movement abnormalities in Huntington's disease
S M Dursun1, J G Burke, H Andrews
1Department of Psychiatry, Faculty of Medicine, University of Leicester, UK. sdursun@is.dal.ca
Insights
Antipsychotic medication does not affect saccadic eye movement abnormalities in Huntington's disease (HD) patients. These eye movement deficits in HD are linked to the disease's neuropathology, not drug effects.
Area of Science:
- Neuroscience
- Ophthalmology
- Neurology
Background:
- Huntington's disease (HD) is a neurodegenerative disorder affecting motor, cognitive, and psychiatric functions.
- Saccadic eye movement abnormalities are frequently observed in neurological conditions, including HD.
Purpose of the Study:
- To investigate the impact of antipsychotic medication on saccadic eye movements in patients with Huntington's disease.
- To differentiate between medication effects and underlying neuropathology contributing to eye movement abnormalities in HD.
Main Methods:
- Prospective open trial involving 16 Huntington's disease outpatients (8 drug-free, 8 on antipsychotics) and 24 healthy controls.
- Utilized the antisaccade task to assess voluntary control of saccadic eye movements.
- Measured antisaccade latencies and error rates as primary outcome measures.
Main Results:
- Both drug-free and medicated Huntington's disease patient groups exhibited significantly more antisaccade abnormalities compared to healthy controls.
- The rate of antisaccade abnormalities was comparable between the drug-free and medicated Huntington's disease patient groups.
- These findings indicate that eye movement abnormalities are not influenced by antipsychotic medication.
Conclusions:
- Saccadic eye movement abnormalities in Huntington's disease are primarily attributed to the underlying neuropathology of the disease.
- Dysfunction in the dorsolateral prefrontal cortex or its subcortical connections (striatum, superior colliculus) is likely responsible for these antisaccade deficits.
Abstract:
1. The study was a prospective open trial done to determine the effect of antipsychotic medication on saccadic eye movements in patients with Huntington's disease (HD). The authors tested 16 outpatients with HD, 8 of whom were drug free and 8 of whom were on antipsychotic medication. We also tested 24 healthy control subjects. 2. The antisaccade task was used to investigate the voluntary control of saccadic eye movements. Antisaccade latencies and error rates were used as outcome measures. Both HD patient groups showed significantly more antisaccade abnormalities than controls and the rate of abnormalities was very similar between the drug-free and medicated patient groups. 3. The results suggest that these abnormalities are related to underlying neuropathology rather than effects of medication. Either specific dysfunction of the dorsolateral prefrontal cortex or of the subcortical circuit connecting this cortical area to the superior colliculus via the striatum are likely to be responsible for the generation of such antisaccade eye movement abnormalities.