Conditions we treat
Substance dependency is a chronically relapsing disorder that has been characterized by Koob and Volkow as a (1) compulsion to seek and take the substance, (2) loss of control in limiting intake, and (3) emergence of a negative emotional state (eg, dysphoria, anxiety, irritability) when access to the substance is prevented.
Substance dependency has been conceptualized as a disorder that involves three stages:
Addictive substances activate parts of the brain that create pleasure/reward, as they increase the levels of dopamine, and they become associated with the people and situations that precede its consumption. With repeated use, the brain does not produce the same level of dopamine whenever the person consumes the substance and the person needs to consume more to have the same reward effect.
As the substance stops producing the same degree of pleasure as it did when the person first started using it due to brain adaptations, he/she sees himself/herself less interested in normal daily activities and relationships that were previously motivating. These brain modifications lead the person to start experiencing negative affect and stronger reactivity to stress, and also when the person does not consume the substance or the direct effect of the substance wears off, he/she experiences withdrawal. As a result of these brain adaptations, the person with the substance addiction transitions from taking the substance simply to feel pleasure to taking it to obtain relief from dysphoria or to escape the distress he/she feels when not intoxicated.
With the changes alluded above, the brain starts to show signs of impairment and lose the ability to think flexibly, to regulate emotions and impulses, make decisions rationally, focusing more and more on the substance, search for it, consume it and experience the effects. This also explains why the person, despite having the desire to stop consuming the substance, will be unable to follow through regardless of the negative consequences.