Deep brain stimulation, a surgical procedure can aid depressed patients who are resistant to other therapies, says study.
The study, conducted by a team led by psychiatrist Sidney Kennedy and neurosurgeon Andres Lozano at the University Health Network in Toronto, Canada, found that the effects can still be seen six years after implanting stimulating electrodes deep inside the brain.
The researchers showed that, within a year of implantation, depression lifted in 12 of 20 patients - and that the benefits were sustained for up to six years.
But two of the patients died by presumed suicide.
The good news is that those who showed an early response to deep-brain stimulation maintained that response, says Kennedy.
"However the suspected suicides indicate that we have not been able to prevent the course of illness," Nature quoted him as saying.
The study has been published online in the American Journal of Psychiatry.