Graph theory of functional connectivity of the motor network. A Effects for graphical theoretical measures of the motor network by group (beta values and standard errors). B Between-group differences in overall efficiency and clustering coefficient of the automobile network. Effects adjusted for MRI hardware and software changes, average displacement per image, age, and gender. HC healthy controls, currently depressed patients, rem patients in remission, PmD psychomotor disorders, PmA psychomotor agitation, PmR psychomotor retardation. Credit: Molecular Psychiatry (2023). DOI: 10.1038/s41380-023-02327-1
A recent study published in Molecular Psychiatry identified previously unknown alterations in neuronal connectivity that promote psychomotor disturbances (a slowing or reduction of movements) in people with major depressive disorder.
“There appears to be a clear underlying pattern of brain connectivity linked to these motor characteristics as well as subtypes of depression. This could lead to new treatments (targeting motor function), as well as ways more accurate in defining and treating people with depression,” said Vijay Mittal, Ph.D., professor of medical social sciences, psychiatry and behavioral sciences, co-author of the study.
Stewart Shankman, Ph.D., Dunbar Professor of Bipolar Disease and professor of psychiatry and behavioral sciences, was co-author of the study.
According to the World Health Organization, around 280 million people worldwide live with major depressive disorder (MDD) and can experience a range of symptoms, including trouble sleeping, poor concentration, feeling low self-esteem, as well as psychomotor disorders.
Up to 70 percent of people with MDD experience psychomotor disorders, manifesting either as psychomotor retardation (a reduction in movement and activity) or psychomotor agitation (repetitive movements leading to restlessness).
Psychomotor disorders have previously been associated with higher severity of MDD and poorer response to antidepressant treatments. However, the underlying neural mechanisms remain poorly understood.
In the present study, a total of 699 participants with remitted or current depression and 820 healthy controls were classified as having psychomotor retardation, psychomotor agitation, or no psychomotor disturbance.
Each participant’s MRI scans were then compared to determine functional connectivity between different sections of the brain’s motor network, which included the primary motor cortex, supplementary motor area, sensory cortex, superior parietal lobe, caudate, putamen, pallidum, thalamus and cerebellum.
Overall, participants with psychomotor delay only had higher thalamo-cortical connectivity, while those with psychomotor agitation had higher pallido-cortical connectivity. Participants with current MDD but without psychomotor disorders also showed higher thalamo-cortical, pallido-cortical, and cortico-cortical connectivity, as well as greater alterations in overall network connectivity compared to controls.
Patients in remission with psychomotor disorders showed no differences in unique connections but differences in overall network connectivity, while patients in remission without psychomotor disorders showed similar connectivity signatures as the control group.
In the future, Mittal said his team hopes to repeat the study with multimodal neuroimaging and clinical assessment of participants’ motor symptoms to determine the root causes of psychomotor delay and psychomotor agitation.
More information:
Florian Wüthrich et al, The neural signature of psychomotor disorders in depression, Molecular Psychiatry (2023). DOI: 10.1038/s41380-023-02327-1
Provided by Northwestern University
Quote: Neural mechanisms may serve as a therapeutic target for depression (January 11, 2024) retrieved January 11, 2024 from
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