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Psychomotor disturbances — ranging from catatonia and psychomotor agitation to disorganized behavior and repetitive movements — are highly prevalent in psychiatric conditions. Despite their high prevalence, the neural mechanisms behind these disturbances have remained elusive.

“There has been an exponential increase in the interest to understand psychomotor processes in disease pathology — the fundamental nature of the motor system enhances our ability to link psychological processes to brain to symptoms, promoting clinically useful targets for intervention,� said senior author Alexandra Moussa-Tooks, PhD, an adjoint professor at Vanderbilt University School of Medicine, and co-director of the Clinical and Cognitive Neuroscience Center and head of the Motor Adaptations in Psychotic Disorders Lab at Indiana University Bloomington.

One of the main focuses of this study is the role of grip strength as a measure of both motor function and overall well-being.

“Grip strength is one measure of motor function that has been associated with all-cause mortality and overall well-being,� said first author Heather Burrell Ward, MD, assistant professor of Psychiatry and Behavioral Sciences at Vanderbilt University Medical Center. “It has been assumed that associations between grip strength and well-being are purely related to mechanical impairments reflective of overall poorer physical health.

“Therefore, the brain correlates of grip strength have been presumed to lie in the motor system, so previous brain analyses are frequently restricted to motor regions.

"However, a unifying brain circuit explanation linking grip strength and overall well-being has remained elusive until now. Ours is the first analysis to link grip strength and well-being to alterations in resting-state functional connectivity.�

This study takes a groundbreaking approach by identifying brain regions beyond the motor system that contribute to grip strength and overall health. Using data from the multisite Human Connectome Project for Early Psychosis, which involved 206 participants, including individuals with early psychosis and healthy controls, the researchers applied a data-driven, connectome-wide analysis to uncover the brain circuits associated with grip strength and well-being.

“We observed that higher grip strength was correlated with greater connectivity from multiple brain regions to the DMN,� Ward said.

Given the associations between grip strength and well-being, researchers then repeated this analysis to determine if they would identify similar brain correlates for grip strength and well-being — and they did.

“We identified significant relationships between the same brain regions and their connectivity patterns to the DMN that were related to well-being, overall function and grip strength,� Ward said. “These results have dramatic implications for treatment of psychomotor function in psychotic disorders, as they suggest a unifying role of DMN connectivity in psychomotor disturbance, overall function and well-being.�

Specifically, interventions targeting DMN connectivity could be used to treat psychomotor disturbance and well-being. Repetitive transcranial magnetic stimulation (rTMS) is one form of noninvasive brain stimulation that can be used to modulate DMN connectivity. As director of Neuromodulation Research in the Department of Psychiatry, Ward is currently leading multiple clinical trials that use rTMS to modulate DMN connectivity for people with psychosis.

“These results are exciting because they provide us with novel insights on what brain regions we should target to improve psychomotor function and overall well-being,� Ward said. “With our state-of-the art, fMRI-guided rTMS research at Vanderbilt, we can now test these interventions to develop novel and highly effective treatments for psychosis.�

Provided by Vanderbilt University Medical Center.