Additionally, they will be evaluating how stimulus location, demographic and/or clinical variables affect clinical response to TMS. After the four-year trial is over, George said he and his team hope to be able to plot who has responded and who hasn't and also gain new guidance about "where we should focus our efforts."
While the vast majority of rTMS prefrontal studies have found that rTMS has efficacy greater than sham, George said, the question remains whether daily prefrontal rTMS will be effective in a general psychiatric nonresearch setting.
Canadian Practice Setting
In Canada, several rTMS devices have been licensed by Health Canada. George described one study in a Canadian practice setting (Ledsome et al., 2005).
"There is a TMS referral system there. They had 77 people referred, and 65 completed the protocol. These are patients who were largely treatment resistant," he said.
The patients were referred by their physicians to a private medical clinic for rTMS treatment. Repetitive TMS was administered over the left prefrontal cortex at an intensity of 120% of motor threshold, frequency of 5 Hz (train length 8 sec, intertrain interval 22 sec, 40 trains) or frequency of 10 Hz (train length 5 sec, intertrain interval 25 sec, 50 trains) once or twice daily for 15 to 20 sessions. Outcome was assessed using the Beck Depression Inventory (BDI) before and after treatment.
In 65 patients, BDI decreased from a pretreatment score of 29.3 (±1.3, SE of mean) to a posttreatment score of 17.8 (±1.7). The response rate (decrease in BDI of 50%) was 46% and the remission rate (a decrease in the BDI to ≤8) was 25%. There was no correlation between age of the patients and percentage change in BDI over the range of 18 to 65 years.
According to news reports, the cost for a course of treatment is estimated at between $3,000 and $6,000, depending upon whether the patient needs maintenance sessions.