Although the effect size was smaller, there was a higher rate of motor signs among participants with a family history of these conditions, Dr. Damme said. “Again, we see that it’s elevated across developmental motor delays and at a similar rate in people who have depression and psychosis.”
In addition, psychomotor agitation was linked to depression with psychosis and depression without it.
Sensorimotor connectivity network data for the cohort indicated there was no main effect of diagnosis on corticostriatal connectivity.
However, more depressive symptoms were related to less connectivity (P = .024). There was a similar finding for psychotic-like experiences. The total number of such experiences related to lower connectivity (P < .001).
During the postpresentation discussion, Ian Kelleher, MD, PhD, honorary clinical lecturer in psychiatry at the Royal College of Surgeons in Ireland, Dublin, said he was “surprised” by the finding that the rate of psychomotor retardation was lower among participants with psychosis and depression.
Dr. Damme noted that some of the motor sign item ratings came by way of a child interview and that some of these item ratings came from the adults in the children’s lives.
She added that she was not entirely sure whether asking an 8- to 11-year-old in a clinical interview whether they are experiencing motor signs “might be the best way to get at motor slowing.”
Subtle features
Commenting on the findings in an interview, Peter F. Liddle, MD, PhD, professor of psychiatry, at the University of Nottingham (England), noted that the “features we’re talking about are pretty subtle.
“What I’ve been wondering about for some time is whether we should be getting video recordings and using machine learning approaches to teach a computer to recognize normal movements vs abnormal movements, and particularly facial expression,” said Dr. Liddle, who was not involved with the research.
He called the current study “interesting” but noted several factors that affect the potential utility of the findings in predicting outcomes.
First, they “may not be very good for distinguishing schizophrenia from mood disorders; but if the question is simply determining which young person might go on to develop a significant mental disorder, then it may be useful,” Dr. Liddle said.
He endorsed the investigators’ conclusion that motor abnormalities may be a transdiagnostic marker. Beyond that, they may be “more useful as a predictor of the likely long-term severity, but that’s my own hypothesis based on my work,” he added.
Another question concerns the sensitivity of motor abnormalities as a predictive marker. With the rate of the abnormalities identified in those who developed psychosis and depression about double the rate in the overall population, “it sounds like those assessors were fairly sensitive. … but not all that specific,” said Dr. Liddle.
A third issue relates to treatment. “By the time people get sent to a psychiatrist for assessment for possible impending psychotic illness, they’ve often already had medication,” typically an antidepressant or antipsychotic.
“It’s very well established that dopamine-blocking antipsychotics produce hypokinesia and also dyskinesia,” which could then become a confounding factor, Dr. Liddle said.
The study was funded by grants from the National Institute of Mental Health. The study authors and Dr. Liddle have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.