Abnormal involuntary movement scores can be predictive of clinical psychosis, according to study results published in Schizophrenia Research. Researchers also indicated a link between abnormal involuntary movements and multiple biological markers, indicating pathophysiological motor cortex involvement.
Researchers evaluated the prevalence of abnormal involuntary movements in patients with a clinical high risk for psychosis or first-episode psychosis. Data were compared with the prevalence of abnormal involuntary movements in a group of clinical controls. Additionally, the investigators assessed both functional and structural brain correlates of observed abnormal involuntary movements.
Participants were recruited from the Bern Early Recognition and Intervention Center in Switzerland. The cohort included 45 patients with a clinical high risk for psychosis, 10 patients with first-episode psychosis, and 39 nonpsychotic/nonclinical high-risk clinical controls. Of this group, a subset underwent standardized cerebral magnetic resonance imaging (MRI); 34 had a functional measure of regional cerebral blood flow, and 38 had structural gray matter magnetic resonance images.
Among patients with a clinical high risk for psychosis, 17 fulfilled ultrahigh risk criteria, 15 fulfilled basic symptom criteria, and 13 fulfilled both. Significantly lower scores on the social and occupational functioning assessment scale were noted in patients with first-episode psychosis compared with the clinical high risk and clinical control groups (P =.007 and P =.005, respectively). Among the magnetic resonance sample, patients with first-episode psychosis were treated with “significantly higher” antipsychotic doses compared with the other patient groups.
Abnormal involuntary movement scores were significantly different between the 3 groups. Post hoc Mann-Whitney tests demonstrated significantly higher total abnormal involuntary movement scores in those with clinical high risk or first-episode psychosis, both compared with the clinical control group. Additionally, there was a significant between-group difference in the percentage of abnormal involuntary movement scores ≥2: 75.6%, 90.0%, and 48.7% in the clinical high-risk, first-episode psychosis, and clinical control groups, respectively.
There was a significant positive correlation between regional cerebral blood flow and abnormal involuntary movement score as detected in the middle frontal gyrus and extending to the precentral gyrus. Following separation by diagnostic group, this effect was statistically significant in patients with clinical high risk.
In the MRI sample, the abnormal involuntary movement score was negatively correlated with caudal middle frontal volume. Following separation by diagnostic group, a significant correlation was noted only in the clinical control group. Finally, abnormal involuntary movement scores were negatively correlated with premorbid verbal intelligence. Diagnostic group separation resulted in a correlation at trend level in those with clinical high risk.
“Our study demonstrates that [abnormal involuntary movements] are prevalent in the psychosis spectrum,” the researchers noted. “While there is some specificity to psychosis, [abnormal involuntary movements] are considered a dimensional feature.”
A limitation to the study is the modest sample size, which researchers noted “restricts the statistical significance and prevented us from comparing subgroups with [for example] specific patterns of motor symptoms.” Another noted weakness is the lack of a healthy control group.
“To our knowledge, this is the first … analysis directly comparing help-seeking [patients] … from an early detection center,” the researchers concluded. “The assessment of [abnormal involuntary movement] in [patients at clinical high risk] might in [the] future be used as an additional predictor for the symptomatic assessment of psychosis risk.”
Kindler J, Michel C, Schultze-Lutter F, et al. Functional and structural correlates of abnormal involuntary movements in psychosis risk and first episode psychosis [published online August 9, 2019]. Schizophr Res. doi: 10.1016/j.schres.2019.07.032