Zapping the Brain

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Recently, a new type of neurosurgery, Deep Brain Stimulation, has been emerging. DBS involves inserting electrodes into the brain that send constant electrical signals. The procedure is reversible, the device can be turned off or on, and the frequency of the electrical pulses can be adjusted. Deep Brain Stimulation has been successfully used to treat Parkinson's disease. Interestingly, this method has been experimentally used to treat psychiatric diseases such as OCD, and may be a viable option for treating depression and addiction as well. The possibility of treating psychiatric disorders with this new method raises several questions, both scientifically and ethically.
In a recent study researchers found that stimulation of the sub-thalamic nucleus may reduce the symptoms of severe OCD. Researchers believe that this stimulation “may modify the maintenance of a decision deferring process...and therefore decrease OCD symptoms”. While successfully reducing symptoms, the procedure proved to be risky. Eleven of the seventeen participants experienced severe adverse events during the trial. Some of these events were related to the surgery itself, and others were behavioral and occurred during the active stimulation phase of the trial (Mallet et.al.). An earlier study applied DBS to the anterior capsules of four patients with severe OCD. Three of the four experienced a decrease in symptoms (Ainsworth).
To many the possibility of treating severe depression with Deep Brain Stimulation seems promising. Reports of relief from depression in Parkinson’s disease patients being treated with DBS in the subthalamic nucleus are encouraging and are prompting more research into the area. Since relatively little is known about the neurobiology of depression, multiple regions of the brain are possible targets for DBS. The STN, the cerebellum, and the thalamus are among the current possibilities. A 2005 study of six patients with treatment-resistant depression found that patients improved significantly after being treated with DBS in the subgenual cingulate, a part of the brain that may be overactive in people with depression (Juckel). Another region of the brain, the nucleus accumbens, is involved in processing reward and pleasure and in regulating emotional behavior. When DBS was applied to this region in three severely depressed patients, their symptoms improved immediately (Ainsworth).
            Using DBS to treat severe depression not only offers hope to desperate patients, but also could help researchers to better understand the neurological causes of depression by comparing the results of stimulation of various brain regions on mood and neuro-chemical levels. Since currently both the exact mechanisms of how DBS works and the neurological causes of depression are poorly understood, the potential for discovery is enormous. The number of areas of the brain to which DBS can be applied as a successful treatment of depression testifies to the complexity of the disorder. It might also be possible that the list of symptoms associated with depression actually have multiple pathologies. There does not seem to be a direct or consistant corralation between stimulation of certain brain regions and mood, as some Parkinson’s disease patients have reported increases in levels of depression after DBS to the subthalamic nucleus rather than decreases.
Though no direct experiments have been done on the affects of DBS on addictions the result of treatment with DBS in the STN of Parkinson’s disease patients suffering from DDS, a dopamine addiction, show that DBS strongly reduces DDS. One patient suffering from both Parkinson’s disease and alcoholism was treated with DBS and subsequently recorded abusing alcohol only one time in the following two-year period. Another patient being treated with DBS in the nucleus accumbens for depression and anxiety disorder also experienced substance abuse problems. Although he showed little reduction in his depression and anxiety symptoms, his substance abuse symptoms decreased significantly. In the Parkinson’s disease patients researchers cannot be entirely certain that the reduction in dopamine and alcohol abuse resulted directly from the DBS or as a by-product of the decrease in their Parkinson’s symptoms. The authors of the study suggest, however, that the loss of addiction was due to direct DBS affects on the reward seeking circuit of the brain (Stelten). If DBS does directly affect the reward seeking area of the brain, does it affect a person’s desire to engage in other rewarding activities as well? There is evidence that this may be the case. A Chinese neurosurgeon, Bomin Sun, found that destroying areas of the nucleus accumbens relieves heroin addicts of their drug cravings, but also causes apathy and inactivity.  Sun has also experimented with DBS of the same area, and in an unpublished study apparently had success in treating two patients for addiction with few side effects (Ainsworth). As it seems that each area of the brain has multiple or yet unknown functions, and that behaviors result not from just one part of the brain but, it would seem almost impossible to modify one element of a person’s behavior in isolation of all other elements.

            Knowing the risks and the possibility of side effects  and unforseen personality changes, it is understandable that there are ethical concerns surrounding the use of DBS in the treatment of psychiatric disorders. DBS might also seem uncomfortably similar to early practices of psychsurgeries. However, unlike these earlier procedures, DBS is reversable and ajustable; and does seem to offer a viable, if somewhat risky, option for people suffering from dibilitating psychiatric disorders.

Works Cited:

Ainsworth, Claire. “Wireheads.” New Scientist, Jan. 5, 2008.

Juckel, Georg; Uhl, Idun; Padberg, Frank; Brune, Martin; and Winter, Christine. “Psychosurgery and deep brain stimulation as ultima ratio treatment for refractory depression.” Eur Arch Psychiatry Clin Nuerosci. 2009. 259:1-7

Mallet, Luc; Polosan, Mircea; Jaafari, Nematollah; and Baup, Nicolas et. Al. “Subthalamic Nucleus Stimulation in Secere Obsessive Disorder.”The New England Journal of Medicine. Boston: Nov. 13, 2008. Vol. 359, Iss 20; pg. 2121

Stelten, Bianca; Noblese, Lieke; Ackermans, Linda; Temel, Yasmin; and Visser-Vandewalle, Veerle. “The nuerosurgical treatment of addiction.”Neurosurg. Vol. 25. July, 2008.