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Novel Therapies for Cognitive Dysfunction Secondary to Substance Abuse: Page 2 of 4

Novel Therapies for Cognitive Dysfunction Secondary to Substance Abuse: Page 2 of 4

The prevalence and durability of cognitive deficits in patients with substance use disorders raises the need to develop specific assessment and rehabilitation strategies. This is pertinent because general deficits in cognitive function and specific deficits in executive functions are robustly associated with worse drug treatment outcomes, including poorer adherence, shorter retention, and greater risk of relapse.14-16

In this article, I propose the use of a brief screening instrument for frontal-executive deficits in patients with substance use disorders and provide examples of novel treatment interventions aimed at addressing these deficits.

Instruments to assess substance use–related cognitive deficits

Key manifestations of cognitive/executive dysfunction among patients with substance use disorders are:

• Difficulties in understanding complex instructions

• Distractibility

• Premature or disinhibited responses

• Thought and behavioral inflexibility

Some other symptoms may be neglected by the patient but stressed by significant collaterals, including problems with initiating and planning novel activities, disorganized behavior, lack of insight into his or her mistakes, and lack of concern about the consequences.

Insight is often lacking in the patient, which underscores the need for the clinician to effectively screen for cognitive dysfunction. If cognitive impairment is suspected in light of clinical observations and interviews, I recommend the use of a brief screening instrument to detect frontostriatal systems–derived cognitive, behavioral, and emotional deficits. For example, the Frontal Systems Behavior Scale (FrSBe) is a sensitive instrument used to detect frontostriatal-related deficits in patients with substance use disorders.17-19

The FrSBe is composed of 46 items (rated on a 1 to 5 Likert scale) that yield 3 scores for symptoms of apathy, disinhibition, and executive dysfunction (working memory, planning, or awareness deficits), as well as an overall score of frontostriatal-systems dysfunction. The scale includes a self-report and a collateral report. Both reports have shown adequate reliability indices, but the use of the latter is especially recommended when the patient’s insight deficits are overtly manifest.17 The scale also possesses norms extracted from the healthy population of the United States, which provides easy classification of patients as impaired or nonimpaired in comparison with demographically adjusted norms.

If the information from the clinical interviews and the scale’s scores converges to suggest at least mild cognitive impairment (below 1.5 standard deviations [SDs] in some of the FrSBe scales), the clinician can complement the assessment by administering a brief battery of neuropsychological tests focused on those cognitive abilities with well-known implications for addiction treatment prognosis (Table). Response inhibition is measured with the Stroop test, the Wisconsin Card Sorting Test (WCST) is used to measure flexibility/perseveration, decision-making capacity is measured using the Iowa Gambling Task (IGT).14-16

The Stroop test measures response inhibition, and it is based on the interference effect driven by the demand of naming the color of a word that is printed in a color incongruent with the name (eg, the word blue printed in red).20 The test consists of 3 conditions. The first condition (W) presents the words red, blue, and green printed in black ink, and patients are requested to read aloud these words. The second condition (C) presents strings of XXX printed in the same 3 colors, and patients have to name the colors as quickly and accurately as possible. The third condition (WC) introduces the interference effect: the words red, blue, and green are printed in incongruent colors and patients have to name the color and ignore the word. The interference score (IS) is calculated by subtracting a weighted mean of the first 2 conditions from the third condition [IS = WC 2 (C 3 W)/(C + W)]; then results are compared with normative values to evaluate the degree of impairment.

The WCST21 is a measure of flexibility to change. It measures response patterns in the face of changing schedules of reinforcement. The clinician presents 4 stimulus cards; the shapes on the cards differ in color, quantity, and design. The patient is given a stack of 64 cards that he has to sort according to initially unknown criteria. However, the examiner knows the criteria (the first sorting criterion is the color of the shapes, the second is the design of the shapes, and the third is the number of shapes) and provides trial-by-trial feedback of the correctness or incorrectness of each card sorted.

Patients try to sort the cards correctly by adjusting their performance to the ongoing feedback. Critically, the sorting criteria change across the test (without any overt warning from the examiner): after 10 consecutive hits in sorting by color, the criterion changes to shape, and then to number.

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