How Happy Is Too Happy? Euphoria, Neuroethics, and Deep Brain Stimulation of the Nucleus Accumbens

Recent studies on deep brain stimulation (DBS) of the nucleus accumbens (NA)-a center of the brain well known to mediate reward, pleasure, and addiction-have provided proof of principle evidence that DBS might be able to induce euphoria in a rapid, well-modulated manner, with potentially much higher efficacy than previous neuropsychiatric interventions. This development evokes two lines of fundamental ethical questions: If happiness were indeed easily inducible by a button press, are there any ethical, psychological, or social limits of DBS-induced happiness? If happiness might be easily inducible not just in persons suffering from psychiatric disease, but also in healthy persons, are there any intrinsic objections against such an enhancement use of DBS? This study uses systematic ethical analysis of recent observations in NA DBS, illustrated by a case vignette and by published reports on other patients. It was found that the benefit of DBS-induced modulation of affective and motivational states comes in degrees: A change in the DBS settings can transform a salutary state of hedonia into a hypomanic or manic state and turn an enhanced affective state into a maladaptive one. Thus, DBS-induced happiness requires an individual, domain-specific functional analysis, which might reveal context-dependent beneficial and detrimental consequences for a person's life. These consequences warrant careful observation of mood states in persons with NA DBS. There are no convincing intrinsic objections against an enhancement use of DBS. However, the lack of evidence about potential benefits, the risk of severe harm, and the high intervention costs currently pose important extrinsic arguments against use of DBS for enhancement purposes.