Background: Dependent cocaine users consistently display cognitive deficits but cognitive performance of recreational cocaine users has rarely been investigated.Aims: To examine whether cognitive performance is impaired in relatively pure recreational and dependent cocaine users.Method: The cognitive performance of recreational (n = 68) and dependent cocaine users (n = 30) was compared with the performance of stimulant-naive controls (n = 68) employing an extensive neuropsychological test battery. Moreover, the impact of attention-deficit hyperactivity disorder (ADHD) symptoms, craving and early age at onset was analysed.Results: Dependent cocaine users display broad cognitive impairments in the domains of attention, working memory, declarative memory and executive functions. The performance of recreational cocaine users in all four domains was intermediate between that of controls and dependent users and they displayed significant deficits foremost in the domains of attention and working memory. In addition, ADHD symptoms, craving and age at onset were important modulators of cognitive function in cocaine users.Conclusions: Cognitive deficits occur at a recreational and non-dependent level of cocaine use. Cocaine use and ADHD seem to have mutually aggravating effects on cognitive impairment.

Background: Maladaptive decision-making is assumed to be a core feature of cocaine addiction. Indeed, numerous studies have reported deficits in non-social decision-making tasks and reward-related impulsivity in dependent cocaine users. However, social decision-making has not been examined in cocaine users yet. Moreover, it is unknown if even recreational and non-dependent cocaine use is linked to decision-making deficits. Therefore, we investigated whether recreational and dependent cocaine users exhibit alterations in social and non-social decision-making.Method: The performance of healthy controls (n = 68), recreational cocaine users (n = 68) and dependent cocaine users (n = 30) in classical decision-making paradigms (Iowa Gambling Task, Delay Discounting) and in social interaction paradigms (Distribution Game, Dictator Game) was assessed.Results: Decisions in the social interaction tasks of both cocaine user groups were more self-serving compared with controls as cocaine users preferred higher monetary payoffs for themselves. In the Iowa Gambling Task, only dependent cocaine users were more likely to choose disadvantageous card decks, reflecting worse decision-making. They were also more likely to choose immediate smaller rewards over larger delayed rewards in the Delay Discounting task.Conclusions: Our results imply that both recreational and dependent cocaine users are more concerned with their own monetary gain when interacting with another person. Furthermore, primarily dependent cocaine users are less foresighted and more impulsive regarding immediate reward. Overall, social interaction deficits are already present in recreational users, while non-social decision-making deficits occur predominantly in dependent cocaine users. Thus, social interaction training and cognitive remediation strategies may improve treatment success and quality of life in cocaine dependence.

Large-scale epidemiological research often uses self-reports to determine the prevalence of illicit substance use. Self-reports may suffer from inaccurate reporting but can be verified with objective measures. This study examined the following: the prevalence of illicit and non-medical substance use with self-reports and hair toxicology, the convergence of self-reported and objectively quantified substance use, and the correlates of under- and overreporting. The data came from a large urban cohort study of young adults (n = 1,002, mean age = 20.6 years, 50% female). The participants provided 3 cm of hair (covering the previous 3 months) and reported their illicit and non-medical substance use and their sociodemographic, psychological, and behavioral characteristics. Hair toxicology analyses targeted cannabinoids, ketamine, opiates/opioids, stimulants including 3,4-methylenedioxymethamphetamine, and relevant metabolites. Self-reports underestimated the prevalence of most substances by 30% to 60% compared to hair tests. The average detection ratio (hair test/self-report) was 1.50. Hair tests were typically more sensitive than self-reports. Underreporting was associated with a low level of that substance in hair. Self-reported delinquency and psychopathology were correlated with an increased likelihood of concordant positive self-reports and hair tests compared to underreporting. Overreporting was associated with infrequent self-reported use. Our study suggests that self-reports underestimate young adults' exposure to illicit substances and non-medical use of prescription drugs. Consequently, estimates of associations between substance use and risk factors or outcomes are likely biased. Combining self-reports with hair tests may be most beneficial in study samples with occasional substance use. Researchers can use specific factors (eg, detection ratios) to adjust prevalence estimates and correlations based on self-reports.