Executive dysfunction in chronic cocaine users: an exploratory study.

Introduction: Chronic cocaine use is associated with some executive deficits. We assessed executive functions using ecologically valid tests in chronic cocaine users.

Objectives: To investigate the relationship between executive deficits and three measures of severity of cocaine use: years of use, quantity used, and frequency of use.

Methods: Twenty-four cocaine users were compared with twenty-seven community controls. We used Student's t-test and Chi-squared to compare means and categorical variables, respectively. Linear regression analyses for the adjusted comparative analysis between cases and controls, and severity of cocaine use among cocaine users were performed.

Results: Chronic cocaine users performed worse on measures of attention and working memory (Forward and Backward Digit Span, p<.001), set-shifting abilities (difference score between the Trail Making B and A, TMB-A, p=.006), cognitive test of mental flexibility and response inhibition (Rule Shift Cards) (p<.001), and prefrontal functioning (Wisconsin Card Sorting Test, WCST, p=.023) than controls. Years of cocaine use were associated with deficits in the Backward Digit Span (p=.041; CI 95%: -.760 to -.002), the TMB-A (p=.026; CI 95%: .687 to 9.761), the Zoo Map (p=.034; CI 95%: -.480 to -.021), and the Rule Shift Cards (p=.006; CI 95%: -.836 to -.164), among others. Quantity of cocaine use was associated with executive deficits measured by the Forward Digit Span (p=.007; CI 95%: -.727 to -.133), the TMB-A (p=.021; CI 95%: 5.304-57.945), and the number of perseverative errors in the WSCT (p=.002; CI 95%: -10.654 to -2.800). Frequency of cocaine was associated with deficits in the Backward Digit Span (p=.042; CI 95%: -1.548 to -.030).

Conclusions: Chronic use of cocaine is associated with executive deficits, which may influence patients' functionality, prognosis, and therapeutic failure.