Advances in neuroscience are changing how mental health issues such as addiction are understood and addressed as a brain disease. Although a brain disease model legitimizes addiction as a medical condition, it promotes neuro-essentialist thinking, categorical ideas of responsibility and free choice, and undermines the complexity involved in its emergence. It proposes a ‘bio-psychosocial systems’ model where psycho-social factors complement and interact with neuro-genetics. A systems approach addresses the complexity of addiction and approaches free choice and moral responsibility within the biological, lived experience and socio-historical context of the individual. We at Nishan examine drug-assisted treatment as an applied case example within our framework. Biology, sociology, and psychology represent three separate pathways to understanding behavior, which may or may not overlap. The lines get blurred sometimes in the study of addiction because these contextual factors may appear together. If an impoverished man becomes an alcoholic, certainly his social state is a factor. But his solution to this particular helplessness is a psychological symptom. Poverty contributes to addiction, but it is not the deepest understanding of it. A model of addiction can be viewed as a foundation from which to organize addiction into a set of fundamental intuitive principles. As such, any model allows its adherents to prioritize problems and to search for and discover solutions to these problems within the context or boundary conditions of the model.