Repetitive magnetic stimulation of the brain may be an effective and safe long-term maintenance therapy for some patients with major depressive disorder, results of a small study suggest.
“There is growing evidence to support the short-term antidepressant effects of repetitive transcranial magnetic stimulation (rTMS), but few published data pertain to the maintenance treatment of patients with DSM-IV diagnosed major depressive disorder,” write Dr. John P. O’Reardon and colleagues from the University of Pennsylvania, Philadelphia.
The researchers examined the long-term efficacy of rTMS in 10 patients, average age of 50 years, with major depressive disorder over periods ranging from 6 months to 6 years. All of the patients had responded to short-term rTMS.
rTMS was applied over the left prefrontal cortex and session frequency averaged 1 to 2 per week, depending on clinical response. A total of 1,831 rTMS sessions were documented over the study period.
The physician-rated scores on the Clinical Global Impressions-Improvement scale were used to assess the effectiveness of rTMS maintenance. These ratings were cross-checked with the patients’ self-rated impressions of symptom improvement.
Of the 10 subjects, five experienced marked benefit from rTMS therapy, according to the report published in the Journal of Clinical Psychiatry. These patients underwent an average of 257 rTMS sessions at a session frequency of 2.1 per week. Three of the patients did not require any concurrent antidepressant medication.
Another two patients experienced a moderate benefit. These subjects received an average of 125 rTMS sessions at a session frequency of 1.8 per week. Both experienced a recurrence of major depressive disorder.
“Three patients experienced only minimal benefit from rTMS and received (an average) of 98 sessions (1.7 per week) each,” O’Reardon’s team notes. “Two of the three patients experienced recurrences of depression, and none maintained a sustained improvement during maintenance therapy despite the addition of antidepressant medication,” they write. “In these patients, rTMS was ultimately discontinued due to inadequate results.”
The investigators point out that the patients who responded most strongly to initial short-term treatment tended to benefit most from maintenance rTMS, but more research is needed to identify patients who are likely to benefit from long-term therapy.