An implanted device that stimulates the vagus nerve has shown promise for people with long-standing, treatment-resistant depression. The corresponding study was published in the International Journal of Neuropsychopharmacology.
"There is a dire need to find effective treatments for these patients, who often have no other options. With this kind of chronic, disabling illness, even a partial response to treatment is life-altering, and with vagus nerve stimulation, we're seeing that benefit is lasting," said lead author Charles Conway, MD, professor of psychiatry and director of the Treatment Resistant Mood Disorders Center at Washington University, in a press release.
For the study, researchers recruited 214 participants with a mean age of 55 years old who had lived with depression for an average of 29 years and who had already tried 13 treatments without success. Conway noted that the sample in the trial ‘represents the sickest treatment-resistant depressed patient sample ever studied in a clinical trial’.
All patients were implanted with a device beneath the skin on their chest that sent electrical signals to their left vagus nerve, although the device was only activated in half the patients during the trial’s first year to allow for comparison. A previous analysis found that after the first year, patients with activated devices reported more time with improved mood, better functioning, and higher quality of life than those with inactive devices.
In the current study, the researchers examined treatment effects after 24 months. They found that 69% of participants who received active treatment from the start of the study showed a meaningful response a year later. Of these, over 80% maintained or improved results after two years in measures of depression, quality of life, and daily functioning.
Among patients who experienced a substantial response- defined as a reduction in symptoms of 50% or more- 92% were still benefiting after two years. Furthermore, over a third of participants who did not improve after the first year reported improvement after two years. Relapse rates remained low among those who responded, especially among those with a strong response. The researchers further found that over 20% of treated patients were in remission after 24 months.
"We were shocked that one in five patients was effectively without depressive symptoms at the end of two years," said Conway.
"Seeing results like that for this complicated illness makes me optimistic about the future of this treatment. These results are highly atypical, as most studies of markedly treatment-resistant depression have very poor sustainability of benefit, certainly not at two years. We're seeing people getting better and staying better,” he added.
Sources: Science Daily, International Journal of Neuropsychopharmacology