Electrodes implanted deep inside the brain may provide considerable relief for just under half of people with the most severe depression for up to nine years, according to one of the longest-running clinical trials of its kind.
鈥淭hey鈥檝e taken the sickest of the sick and made almost half of them better, which is quite remarkable,鈥� says at the University of Queensland, Australia, who wasn鈥檛 involved in the study.
The trial鈥檚 25 participants had tried antidepressants, psychotherapies and electroconvulsive therapy for their severe depression, all without success.
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鈥淭hey were at the point where they were sitting at home just trying to survive the day. They weren鈥檛 able to work, most did not have any social activities and many had had suicide attempts or were considering euthanasia,鈥� says , who led the trial at Amsterdam UMC, a medical centre in the Netherlands. 鈥渧oluntary and well-considered and [if the physician is satisfied] that his [or her] suffering is unbearable with no prospect of improvement鈥�.
As part of the trial, the participants had tiny electrodes 鈥� each a few millimetres across 鈥� surgically implanted into a circuit of the brain that is implicated in severe depression.
Implanted between 2010 and 2014, the electrodes released impulses that it was hoped would improve connections within this circuit. 鈥淚t鈥檚 like adding noise to a telephone cable 鈥� participants with severe depression have too much communication between certain brain areas, but adding this noise normalises this communication,鈥� says Bergfeld.
The participants were monitored for six to nine years until a final check-up in 2019. At this point, 44 per cent were considered to have significantly benefited from the treatment, defined as their depression score reducing by 50 per cent or more from baseline. They also experienced a vast improvement in their quality of life.
鈥淸They] were able to pick up new activities 鈥� hobbies, social activities and volunteering work 鈥� and some were even able to go back to work,鈥� says Bergfeld.
Another 28 per cent partially benefited from the treatment, meaning their depression score reduced by 25 to 50 per cent. The remaining 28 per cent had zero or minimal improvements.
To check that those who improved hadn鈥檛 simply experienced a placebo effect, the trial included a 12-week period in which the electrodes were switched off for half the time, without the participants knowing when. Their depression scores then worsened, on average, suggesting the treatment effects are genuine.
It is unclear why some participants didn鈥檛 benefit from the deep brain stimulation, but one reason may have been that their electrodes weren鈥檛 hitting the right brain targets, says Mosley. 鈥淚f they鈥檙e a millimetre or two in the wrong direction, they don鈥檛 work,鈥� he says.
Several other small trials of deep brain stimulation for severe depression have found positive effects, but not all. The trials with positive results have tended to monitor participants for longer, says Mosley. 鈥淵ou can鈥檛 just flick a switch in the brain and change someone from depressed to not depressed 鈥� it takes time,鈥� he says.
Bergfeld and his colleagues are now conducting a second trial to see if they can replicate their first study鈥檚 results. 鈥淚f we manage to show an effect in more patients, then the ambition is to make this a standard treatment that鈥檚 more widely available to more patients,鈥� he says.
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