Transcranial Magnetic Stimulation May Cause Improvements in Memory

Transcranial magnetic stimulation (TMS) produced improvements in key areas of cognition and in short-term verbal memory in patients with major depressive disorder, and no adverse cognitive effects were shown.¹ The results of this research were presented by Mark Demitrack, MD, vice president and chief medical officer of Neuronetics, Inc, and colleagues at the annual meeting of the American Psychiatric Association in May.

In this study, cognitive function was examined in patients with pharmacoresistant major depressive disorder. Of these patients, 155 received TMS therapy and 146 received sham TMS. Results of the Mini Mental Status Examination, Buschke Selective Reminding Test, and Autobiographical Memory Interview-Short Form were obtained before the first treatment and at 4 and 6 weeks during an acute treatment course of daily TMS.

No significant difference was found between the active TMS group and the placebo TMS group in any of these measures of cognitive function. At the end of the 6 weeks, each group was stratified by clinical outcome. Within the TMS responders group, there was significant improvement in scores on the Buschke Selective Reminding Test for short-term recall and delayed recall. This improvement in cognitive function was not seen in placebo-treated patients.

TMS differs from electroconvulsive therapy (ECT) in that “it does not require a seizure to attain benefit and is not associated with any cognitive disruption,” said Philip G. Janicak, MD, professor of psychiatry at Rush University, Chicago, who has conducted independent TMS research and was principal investigator in the NeuroStar clinical trials. Furthermore, TMS is nonsystemic and noninvasive and produces localized neuronal changes using intense, brief magnetic pulse trains usually applied over the left dorsolateral prefrontal cortex. It utilizes an electromagnet placed on the scalp that generates magnetic field pulses that approximate the strength of an MRI scanner. The most notable findings in this research, says Janicak, are “the benign nature of the treatment with a virtual lack of systemic adverse effects and its benefit in some very depressed patients inadequately responsive to standard meds or psychotherapy.”

Patients with schizophrenia and related forms of psychosis who present with auditory/verbal hallucinations may also benefit from TMS therapy, according to research from Ralph E. Hoffman, MD, professor of psychiatry at Yale University School of Medicine, New Haven, Conn. In his research, he uses TMS equipment manufactured by Magstim®, which is currently considered to be investigational.

In Hoffman’s experience, adverse effects may depend on where the TMS is administered in the brain. In his current clinical trial, the coil is positioned over Wernicke’s area and the right homologue of Wernicke’s area.² “Side effects have been minimal,” he said. He added that in his research, “neuropsychological testing has not confirmed any consistent changes in function after TMS is administered.”

While Hoffman does not foresee TMS therapy as first-line treatment for depression in the future, both Demitrack and Janicak are more optimistic. Janicak notes that mainstream depression treatment using TMS is feasible “with continued developments and refinement in its application in combination with its safety and tolerability profiles.” Demitrack concurs: “the benefits of TMS in our studies and in the now 2 decades of prior scientific research clearly confirms its important role in the management of a devastating human disease.”

References:

References
1. Demitrack M, Lao C, Maixner D, et al. Transcranial magnetic stimulation (TMS) in the treatment of pharmacoresistent depression: examination of cognitive function during acute treatment [Poster NR4-038]. Presented at: the American Psychiatric Association Annual Meeting; May 16-21, 2009; San Francisco. Abstract.
2. Repetitive Transcranial Magnetic Stimulation Research Clinic at Yale-New Haven Psychiatric Hospital.

. Accessed June 16, 2009.