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The Addiction Process

In the “Impaired Response Inhibition and Salience Attribution” (I-RISA) model, we have emphasized the interaction between inhibitory control (e.g., willed-control over automatic processes, interruption of ongoing behavior) and reward processing (e.g., the experience of pleasure, attribution of relative reward value) in drug addiction, implying that inhibitory control would be especially disturbed under conditions of high drug salience (Goldstein & Volkow, 2002). Preliminary fMRI BOLD results - money differentially activates the brain reward circuit as a function of drug addiction - support our hypothesis.

The brain circuits we target are the mesolimbic and mesocortical dopamine pathways encompassing the striatum (caudate, putamen, nucleus accumbens), hypothalamus, amygdala, anterior cingulate, insula, and orbitofrontal cortex.  The behaviors that are at the core of drug addiction include drug intoxication/drug reinforcement, craving, bingeing, and withdrawal.

 

Basic Neuropsychological Questions

• Does drug addiction impair cognitive function?

• Are there associated personality-emotional changes? If so, to what extent?

• What are the cognitive-behavioral impairments and emotional changes most characteristic of drug (particularly psychostimulant) addiction?

• Are there differences between the various classes of drugs of addiction in their effects on psychological functioning?

• What are the similarities with other non-drug forms of addiction (e.g., gambling)?

• What is the neurobiological basis of each of these changes? Are there parallel changes in the underlying neural networks that can be mapped/imaged?

Methods

We have designed an extensive neuropsychological battery which is administered to all subjects that participate in our fMRI and PET studies (e.g., drug addicted subjects, individuals at-risk for developing drug addiction, healthy controls) to allow for both between- and within-group comparisons. This battery of tests includes:

(1) paper-and-pencil or computerized cognitive-behavioral tasks that assess attention, memory, emotional processing, motor speed, and executive functions (inhibitory control, shifting, planning, reasoning);

(2) self-report measures of emotional states/tendencies and personality traits such as impulsivity, depression, anger;

(3) newly developed computerized tasks that target the behaviors (e.g., sensitivity to reward, predisposition to aggression) associated with the mesolimbic and mesocortical pathways.