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Repetitive Transcranial Magnetic Stimulation For Major Depression Increases Cortical Excitability Without Impairing Cognition
A DGReview of :"Left dorso-lateral repetitive transcranial magnetic stimulation affects cortical excitability and functional connectivity, but does not impair cognition in major depression"
Progress in Neuro-Psychopharmacology & Biological Psychiatry
09/06/2002
By Andrew A. Skolnick
Repetitive transcranial magnetic stimulation appears to be a safe treatment for major depression. The magnetic stimulation increases cortical excitability and functional connectivity without impairing cognition.
Transcranial magnetic stimulation has been used for over a decade to investigate cortical function. More recently, it has been employed to treat psychiatric conditions such as major depression.
Dr. Polash M. Shajahana, at the University of Edinburgh, in Edinburgh, Scotland, and colleagues investigated the effects of differential treatment parameters, such as stimulation frequency.
Fifteen patients with major depression were entered into a study involving treatment with repetitive transcranial magnetic stimulation over the left dorso-lateral prefrontal cortex and brain-functional imaging with single photon emission computed tomography (SPECT).
The investigators compared brain perfusion during a verbal fluency task before and after stimulation. Patients were then treated with 80 percent of motor threshold for a total of 10 days, using 5000 stimuli at 5, 10 or 20 Hz. Tests of cortical excitability and neuropsychological tests were done throughout the trial.
Patients generally improved with treatment, the researchers noted. However, they observed no perceptible difference between stimulation frequencies, which they said may be due to the low study power.
SPECT studies showed an increase in rostral anterior cingulate activation after the first treatment day that was associated with increased functional connectivity in the dorso-lateral frontal loop on the left and the limbic loop on both sides, the investigators reported. No noticeable deterioration in neuropsychological function was observed.
"Transcranial magnetic stimulation at the stimulation frequencies used seems to be safe over a course of 5000 stimuli," they concluded. "It appears to have an activating effect in anterior limbic structures and increase functional connectivity in the neuroanatomical networks under the stimulation coil within an hour of stimulation."
Prog Neuropsychopharmacol Biol Psychiatry 2002; 26: 945-954
"Left dorso-lateral repetitive transcranial magnetic stimulation affects cortical excitability and functional connectivity, but does not impair cognition in major depression"
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