Is Addiction a Brain Disease?

Kent C. Berridge
Neuroethics (2016). pp 1-5.
doi:10.1007/s12152-016-9286-3

Abstract

Where does normal brain or psychological function end, and pathology begin? The line can be hard to discern, making disease sometimes a tricky word. In addiction, normal ‘wanting’ processes become distorted and excessive, according to the incentive-sensitization theory. Excessive ‘wanting’ results from drug-induced neural sensitization changes in underlying brain mesolimbic systems of incentive. ‘Brain disease’ was never used by the theory, but neural sensitization changes are arguably extreme enough and problematic enough to be called pathological. This implies that ‘brain disease’ can be a legitimate description of addiction, though caveats are needed to acknowledge roles for choice and active agency by the addict. Finally, arguments over ‘brain disease’ should be put behind us. Our real challenge is to understand addiction and devise better ways to help. Arguments over descriptive words only distract from that challenge.

The article is here.

Dopamine Modulates Egalitarian Behavior in Humans

Ignacio Sáez, Lusha Zhu, Eric Set, Andrew Kayser, Ming Hsu
Current Biology (2015) March, Volume 25, Issue 7, p. 912–919

Summary

Egalitarian motives form a powerful force in promoting prosocial behavior and enabling large-scale cooperation in the human species. At the neural level, there is substantial, albeit correlational, evidence suggesting a link between dopamine and such behavior. However, important questions remain about the specific role of dopamine in setting or modulating behavioral sensitivity to prosocial concerns. Here, using a combination of pharmacological tools and economic games, we provide critical evidence for a causal involvement of dopamine in human egalitarian tendencies. Specifically, using the brain penetrant catechol-O-methyl transferase (COMT) inhibitor tolcapone, we investigated the causal relationship between dopaminergic mechanisms and two prosocial concerns at the core of a number of widely used economic games: (1) the extent to which individuals directly value the material payoffs of others, i.e., generosity, and (2) the extent to which they are averse to differences between their own payoffs and those of others, i.e., inequity. We found that dopaminergic augmentation via COMT inhibition increased egalitarian tendencies in participants who played an extended version of the dictator game. Strikingly, computational modeling of choice behavior revealed that tolcapone exerted selective effects on inequity aversion, and not on other computational components such as the extent to which individuals directly value the material payoffs of others. Together, these data shed light on the causal relationship between neurochemical systems and human prosocial behavior and have potential implications for our understanding of the complex array of social impairments accompanying neuropsychiatric disorders involving dopaminergic dysregulation.

The entire article is here.