Source: Economist
Date: 3 March 2005

Deep impact

A way of switching depression off

ROB MATTE, a 38-year-old Canadian laboratory technician, suffered from severe depression for 20 years. He had tried everything: psychotherapy, anti-depressant drugs (several varieties) and a gruelling three-week course of electro-convulsive therapy. Nothing worked. Then his psychiatrist told him about an experimental operation using a technique called deep-brain stimulation (DBS) that was being conducted at Toronto Western Hospital, in Canada. In spite of the risk of brain haemorrhage, infection or seizure, Mr Matte signed the consent form. For him, the next step would have been suicide.

Mr Matte is one of six people who have been part of this pilot study into the use of DBS for treating depression. It is being carried out by Helen Mayberg, Andres Lozano and their colleagues at Toronto Western. Their results have just been published in Neuron, and though the sample is small, the outcome is astonishing. For Mr Matte and three others, the treatment worked completely. As soon as the electrodes implanted in their brains were switched on, they noticed a difference. Mr Matte describes how everything in the room became brighter. Lights and colours seemed more vivid. His depression vanished so dramatically that it left him feeling terrified—and it remained vanished, not only for the six months of the study, but also for the six months since it was completed. And none of the patients involved has experienced noticeable cognitive impairment as a result of the operation.

The study was conceived when Dr Mayberg discovered, using a brain-scanning technique called positron-emission tomography, that an area of the brain called the subgenual cingulate is overactive in patients with depression. This got her thinking. Neural overactivity is known or suspected in several other conditions, including chronic pain, dystonia, epilepsy, Tourette's syndrome, essential tremor, obsessive-compulsive disorder and Parkinson's disease. All of these illnesses may be treated with DBS. And in the case of Parkinson's disease it is known that the treatment dampens neural activity.

That is what happened in the successful cases in this experiment, too. Indeed, not only did electrical current fed into the subgenual cingulate suppress its activity, it also re-invigorated activity in the frontal cortex, the hypothalamus and the brainstem—all areas which themselves become dampened in depression.

There is a price to pay. Not only do patients have electrodes implanted in their brains, they also have a battery implanted into their chests (in the case of men) or their stomachs (in the case of women, to avoid damage to the breast tissue). But that is a small charge for resisting suicide.

According to the World Health Organisation, depression is the leading cause of disability in the world. Of the estimated 121m people who suffer from it, 15-30% have “refractory” cases like those treated by Dr Mayberg and Dr Lozano—that is, they do not respond to any treatment. If bigger studies prove this new approach to treating refractory depression works on even a fraction of that fraction, neurosurgeons could be in for a busy time.

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