first , neuroscience research on animals and human neuroimaging studies have identified the brain reward circuits involved in drug effects and addiction . what 's more , researchers have been able to reduce self - administration of addictive drugs in animals by stimulating or ablating these regions in the dopaminergic reward pathway ( see ) . second , there are case studies in which deep brain stimulation has reduced addictive behaviour in patients treated for parkinson 's disease . two patients with parkinson 's disease treated with deep brain stimulation were able to overcome the compulsive use of their dopamine replacement therapy . similarly , parkinson 's disease patients who developed gambling problems or hypersexuality while taking dopamine replacement therapy have reported that these disorders disappear following deep brain stimulation treatment . these observations are supported by small case series in which deep brain stimulation has reportedly reduced addiction to nicotine , alcohol , and heroin in patients treated for other disorders [ 6 - 8 ] . for example , a woman whose agoraphobia was unsuccessfully treated by bilateral deep brain stimulation of the nucleus accumbens reported improvements in her alcohol dependence . the same group conducted a retrospective study of ten smokers who underwent deep brain stimulation of the nucleus accumbens for tourette 's syndrome , ocd , or anxiety and found that three had stopped smoking . the variability of this sample and their intention to quit makes interpreting this study difficult . this evidence is supported by the apparently successful neurosurgical ablation of the nucleus accumbens for heroin addiction by chinese neurosurgeons . there is also one report in which deep brain stimulation of the nucleus accumbens greatly reduced alcohol craving and consumption in three long - term , treatment - refractory , alcohol - dependent individuals ; two were abstinent after one year and a third had markedly reduced their drinking . first , there are important differences between the case for deep brain stimulation in parkinson 's disease and that for addiction . patients with parkinson 's disease who no longer respond to dopamine replacement treatment face a course of irreversible deterioration in motor function and increasing disability . in contrast , addiction does not usually follow an inexorable path to severe disability and death ; it is generally more amenable to pharmacological and psychotherapeutic treatment , so drastic remedies are less justifiable . in fact , many of the failures of addiction treatment are due to inadequate access to well - run and optimally provided forms of existing treatments ; a situation that could be exacerbated by an increased use of deep brain stimulation to treat drug addiction . second , the history of neurosurgical treatment in psychiatry cautions against uncritically accepting  positive results  from uncontrolled and often selectively reported clinical case series . for example , the two case reports of parkinson 's disease patients successfully treated with deep brain stimulation for dopamine dysregulation syndrome   need to be balanced against a larger study that found that 12 of 17 such patients were unimproved or worse after deep brain stimulation . deep brain stimulation has also been reported to induce addictive behaviour in some cases . and while ablative neurosurgery for heroin addiction reduced drug use in some patients in the short term , subsequent long - term follow - up found that it carried significant side effects and was not as effective as first thought . these published case studies provide a weak evidence base to assess the safety and efficacy of deep brain stimulation in addiction . reversible  alternative to neurosurgery , but it is nonetheless an invasive intervention that carries significant risks : 11% of patients have adverse events from surgery and 4% of parkinson 's disease patients suffer intracerebral haemorrhages . insertion of stimulating electrodes can cause serious infections and produce cognitive , behavioural , and emotional disturbances . for the use of deep brain stimulation in the treatment of addiction to be justified , the benefit of the treatment needs to outweigh the damage that it may cause and the negative consequences of not providing the treatment . evidence suggests that the very uncertain benefits of deep brain stimulation in alleviating the symptoms of addiction do not outweigh the known harms associated with the procedure , or the harm of not providing deep brain stimulation ( on the assumption that other currently available treatments are provided to the highest standard ) . fourth , deep brain stimulation for addiction is an expensive form of treatment for addictive disorders where access to existing treatment remains poor . an expensive neurosurgical treatment that costs around us$50,000 ( with maintenance costs of approximately us$10,000 over the next few years ) will utilise scarce health resources to treat a very small number of addicted patients with the income to pay for it , while failing to treat the majority . for trials of deep brain stimulation to be justifiable in patients with addiction , the following requirements need to be met . first , there needs to be strong evidence that any participants in such trials suffer from a severely debilitating form of addiction that carries a high risk of morbidity or premature death and that has not responded to adequate trials of effective treatments . second , there needs to be a reasonable expectation that the intervention will improve the patients quality of life . this should include preclinical evidence of likely benefit , evidence on the long - term effects of deep brain stimulation on patients with other psychiatric conditions ( e.g. , ocd and depression ) , and a good theoretical basis for stimulating the targeted brain region . accordingly , we believe that it would be premature to trial deep brain stimulation in the treatment of addiction on the basis of available animal models , the small number of selected case studies , and the evidence from uncontrolled studies of neurosurgery for heroin addiction . we have outlined above the type of research in animals and individuals required to make a case for undertaking trials of deep brain stimulation in the future . we also support calls for the creation of a register of all cases treated with deep brain stimulation , as suggested recently , to minimise the potential of selective publication of good outcomes . however , even if these conditions are met and deep brain stimulation proves to be safe and effective in treating addiction , we suggest that the high costs involved make it a lower priority for public funding than trials of pharmacotherapies .
deep brain stimulation has been put forward as a potential  cure  for intractable drug addiction . 
 this is largely based on preclinical studies in animal models of addiction and small case series of positive , but short - term , effects on addictive behaviour in highly selected individuals . 
 the history of neurosurgical treatment for psychiatric disorders suggests that we should be cautious in prematurely advocating invasive neurosurgical procedures on the basis of such limited evidence . 
 further research is required in animal models of addiction and in people treated for other neurological or psychiatric disorders before trials in addicted populations can be justified .