NEW YORK (Reuters Health) Jan 29 - Noninvasive transcranial magnetic stimulation (TMS) of the dorsolateral prefrontal cortex relieves the core symptoms of posttraumatic stress disorder (PTSD), according to an online report in the Journal of Clinical Psychiatry.

Repetitive TMS (rTMS) has been tested in several small studies and is emerging as a potentially effective treatment for PTSD, the authors explain.

Led by Dr. Felipe Fregni, from Beth Israel Deaconess Hospital in Boston, Brazilian and American researchers studied 30 patients to evaluate the effect of high-frequency rTMS on core PTSD symptoms - such as hyperarousal, flashbacks, vigilance, intrusive thoughts, emotional numbness, and withdrawal - as well as on anxiety and depression.

Patients were randomized either to right-side rTMS, left-side rTMS, or sham procedures. The treatments were given in 10 sessions every weekday for 2 weeks. The 3 groups were similar in terms of medications.

At 5 and 10 days, right or left rTMS induced significant decreases in PTSD symptoms, whereas sham treatments had no significant effect.

Improvements in the PTSD Checklist and the Treatment Outcome PTSD Scale were greater after right rTMS than after left rTMS, but the differences were only marginally significant.

The improvement in avoidance and hyperarousal was larger after right rTMS than after left rTMS, the investigators say, whereas the improvement in reexperiencing was similar for the two sides.

Depression scores were significantly improved only after left rTMS treatment, and anxiety scores were significantly improved only after right rTMS treatment.

Performance in verbal fluency (as measured by the Controlled Oral Word Association Test) improved only after right rTMS, but other changes in cognitive function did not differ significantly between right and left rTMS.

The beneficial effects persisted to last follow-up (at 3 months) for both the PTSD Checklist and the Treatment Outcome PTSD Scale.

"This study supports the continuation of clinical investigation of brain stimulation for the treatment of PTSD," the authors conclude.

"Our results confirm that high-frequency rTMS over the right dorsolateral prefrontal cortex may be the best approach in most patients," they add, "yet we suggest that patients with high levels of depression may show greater benefit from high-frequency rTMS applied over the left dorsolateral prefrontal cortex."

J Clin Psychiatry 2009.