The main performance index from the test is the percentage of perseverative errors, ie, the percentage of trials in which the patient incorrectly sorts the card by using a criterion that was correct in previous trials but now is no longer valid. This index of flexibility can be contrasted with published normative values to define the degree of impairment.21
The IGT is a computer task that factors several aspects of decision making: uncertainty, risk, and evaluation of reward and punishing events.22 The IGT involves 4 decks of cards, A, B, C, and D. Each time the patient selects a card, a specified amount of play money is awarded. However, interspersed amongst these rewards are probabilistic punishments (monetary losses with different amounts). Two of the decks of cards (A and B) produce high, immediate gains; however, in the long run, these 2 decks will take more money than they give, and therefore they are considered to be the disadvantageous decks. The other 2 (C and D) are advantageous decks, and they result in small, immediate gains, but in the long run, they will yield more money than they take.
The main dependent variable with this task is the net score for the total 100 trials, calculated by subtracting the number of disadvantageous choices (decks A and B) from the number of advantageous choices (decks C and D).
An illustration of the format of these tests is provided in the Figure. The deliverable of this assessment would be a limited but selective profile of the cognitive deficits (scores below 1.5 SDs) of the individual in relation to executive skills thought to be critical for the success of addiction treatment and for the maintenance of sobriety. If a more thorough assessment is required, for example, for more definitive testing, for a neuropsychological diagnosis, because of a court demand, or for formal rehabilitation planning, psychiatry clinicians should refer patients following their health institution’s intra-mural guidelines or, if necessary, request assistance from the Nation-al Academy of Neuropsychology (www.nanonline.org).
Some important recommendations for conducting an appropriate cognitive screening in patients with substance use disorders follow. Make sure that patients have been abstinent from any drug for at least 72 hours. If patients are following substitution pharmacotherapy or other pharmacological treatments, the assessment should be made during the stabilization period. Assessments should take into account the influence of mood states and fatigue; hence, they should be conducted, if possible, when emotional symptoms are not intense and at the time of the day when individuals can perform optimally. Follow-up assessments with the aim of tracking potential recovery (or durability of impairment) can be scheduled every 3 months, since there is no indication of significant cognitive changes during shorter periods.
Recovery of cognitive function and treatment of cognitive impairment
Spontaneous recovery is by far the less explored aspect of cognitive dysfunction in patients with substance use disorders. Most studies in the field are cross-sectional and include patients with relatively short-term drug abstinence. Keeping in mind these important limitations, we came up with 2 main conclusions:
• Different profiles of drug use are associated with different rates of recovery
• Different cognitive skills have different rates of recovery
Our findings suggest 2 temporal milestones for potential recovery: mid-term recovery (between 1 and 6 months of abstinence) and long-term recovery (more than 6 months of abstinence). In cannabis use disorders, only memory and planning deficits are observable at mid-term recovery; at long-term recovery, deficits are often negligible, with residual deficits restricted to planning/organization skills.