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Facial motor abnormalities in individuals at risk for psychotic onset
Author(s)
Date Issued
2021
Citation
Wang, S. M., & Lam, Y. H. (2021 Apr 17-21). Facial motor abnormalities in individuals at risk for psychotic onset. SIRS 2021.
Type
Conference Paper
Abstract
Background: Earlier studies have indicated that individuals at risk for psychotic onset have
facial motor abnormalities. Moreover, more severe facial motor abnormalities predict a higher
probability of subsequent transition to full-blown psychotic diseases in at-risk individuals. It is
of clinical value to explore existence of other motor abnormalities in at-risk individuals because
results will greatly benefit future studies identifying reliable risk factors of psychotic onset. In
drug-naïve first-episode schizophrenia patients, bradykinesia and dyskinesia are common
motor abnormalities. However, earlier studies examining facial motor abnormalities in at-risk
individuals mainly focused on dyskinesia. Little has been known about whether both facial
bradykinesia and facial dyskinesia exist in at-risk individuals. Therefore, this study was to
examine whether at-risk individuals had facial bradykinesia and facial dyskinesia. Measuring
facial motor abnormalities in at-risk individuals is challenging because their facial motor
impairments are subtle and easily missed if observation-based measures are used. In order to
overcome this measuring challenge and be able to sensitively and objectively measure facial
bradykinesia and dyskinesia in at-risk individuals, this study used motion analysis technology.
Methods: A total of 13 at-risk individuals and 13 healthy controls were recruited in this study.
A score of or larger than 17 in Schizotypal Personality Questionnaire-Brief was used to identify
at-risk individuals from the community. The VICON motion capture system was used to
capture three-dimensional trajectory data of the reflective marker attached to the medial side
of the left eyebrow of the participant when s/he showed facial expression of surprise to the
maximal level. On the basis of captured data, the normalized movement time (nMT) and the
normalized number of movement units (nNMU) were calculated to reflect bradykinesia and
dyskinesia respectively. The independent sample t test was used to compare nMT and nNMU
between at-risk individuals and healthy controls.
Results: At-risk individuals (age: 20.46±3.09 years; 5 men and 8 women) and healthy controls
(age: 20.06±1.80 years; 5 men and 8 women) were matched by age (t=-.41, p=.687) and sex.
Significant differences between at-risk individuals and healthy controls were found in nMT
(.08±.05 and .05±.02 respectively; t=-2.08, p=.049) and nNMU (.34±.19 and .20±.10
respectively; t=-2.21, p=.040).
Discussion: Individuals at risk for psychotic onset have both facial bradykinesia and facial
dyskinesia. Results of this study and earlier research show that both bradykinesia and
dyskinesia in the face exist across different stages of schizophrenia, including the at-risk stage,
the drug-naïve first-episode stage, and the chronic stage. These results reflect that facial
bradykinesia and facial dyskinesia are core manifestations of the schizophrenia disease. Future
studies further examining whether facial bradykinesia, like facial dyskinesia, is a predictor of
the imminent onset of psychotic diseases in at-risk individuals are warranted.
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