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Mixture analysis of pursuit eye-tracking dysfunction in schizophrenia
J A Sweeney1, B A Clementz, M D Escobar
1Department of Psychiatry, University of Pittsburgh, PA.
Biological Psychiatry
|September 1, 1993
Summary
Schizophrenia patients show varied eye-tracking errors, but this heterogeneity is not due to distinct eye movement abnormalities. Anticipatory saccades, not true differences, explain performance variations in spatial (RMS) eye-tracking error.
Area of Science:
- Neuroscience
- Psychiatry
- Ophthalmology
Background:
- Recent studies suggest subgroups of schizophrenia patients exhibit deviant eye tracking.
- This potential heterogeneity in eye tracking could indicate underlying pathophysiologic or etiologic differences in schizophrenia.
Purpose of the Study:
- To investigate the heterogeneity of eye-tracking abnormalities in schizophrenia.
- To determine if observed differences in spatial (RMS) eye-tracking error reflect true heterogeneity in specific eye movement disturbances.
Main Methods:
- Analysis of eye-tracking data from 101 consecutive-admission schizophrenic patients.
- Comparison of spatial (RMS) eye-tracking error and pursuit eye movements between patient subgroups and normal controls.
- Assessment of the frequency of anticipatory saccades in different groups.
Main Results:
- Two distinct subgroups of schizophrenic patients with high and low spatial (RMS) eye-tracking error were identified.
- No heterogeneity was found in the disturbance of pursuit eye movements.
- Anticipatory saccades were more frequent in the high RMS error group, explaining the apparent heterogeneity in global indices.
Conclusions:
- Apparent heterogeneity in global eye-tracking impairment in schizophrenia is likely a measurement artifact.
- The influence of anticipatory saccades on performance indices, rather than true heterogeneity, accounts for observed differences.
- Specific eye movement abnormalities do not appear to be heterogeneously expressed in schizophrenia patients.