Eating, hydration, sex, and defending oneself are genetically important behaviors associated with species and individual survival, thus rewarded by intrinsic dopamine and opioidergic systems. Addictive disease in various forms, usurp this survival system by providing reward far beyond the normal human experience through mechanisms that fool the brain into releasing its rewarding effects for behaviors that are actually self-destructive.
Dopamine in the Brain
In this astute article by Volkow and colleagues, the authors assert that addictive, reward-seeking behaviors are influenced by a person’s past and present experience with the reinforcing stimuli (such as drugs or energy-rich foods) that increase the likelihood and/or strength of the cue driven behavioral response (such as drug taking or overeating).
Behavioral change is dependent on the concentration of extrasynaptic dopamine present in specific brain areas such as the striatum. Pavlovian cues that produce conditioned and highly reinforcing stimulus also modulate dopamine volume and create anticipatory reward. Persistent use of an addictive substance produces conditioned pairing between the reinforcement and the specific cues that activate desire and wanting. Over time, repeated exposure produces downregulation in dopaminergic response to other previously incentivizing stimulus and a degraded capacity for inhibitory control. What follows are more impulsive and compulsive responses to food or drug cues.
Why Does This Matter?
Research by Dr. Volkow has established that dopamine reward contributes to addiction and obesity via the “dopamine motive system”. When impaired by addiction, downregulation of dopamine receptors can result in compulsive, habitual and rigid response to ingesting mood altering substances. New and novel interventions and treatment modalities to restore the dopamine balance in the reward system may potentially offer therapeutic remedy for both obesity and addiction.
Volkow ND, Wise RA, Baler R. The dopamine motive system: implications for drug and food addiction. Nat Rev Neurosci. 2017 Nov 16;18(12):741-752. doi: 10.1038/nrn.2017.130. Review. PMID: 29142296