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Cognitive impairment in cocaine users: evidence from cross-sectional and longitudinal analyses


Vonmoos, Matthias. Cognitive impairment in cocaine users: evidence from cross-sectional and longitudinal analyses. 2013, University of Zurich, Faculty of Arts.

Abstract

The United Nations Office on Drugs and Crime currently estimates the annual number of cocaine users at about 17 million people worldwide, resulting in a total retail market of about 85 billion USD per year (2011; 2013). Although the use of cocaine is a widespread public health issue, there are still many open questions considering its concrete consequences. For now more than two decades, research has tried to examine the impact of cocaine use on cognition, primarily by focusing on dependent cocaine users. In recent years, the focus expanded to the more relevant type of recreational and non-dependent cocaine user (European Monitoring Center for Drugs and Drug Addiction, 2012). In this context, a growing body of literature consistently linked the longterm use of cocaine to different effects in cognitive control (Jovanovsky et al., 2005; Perry & Carroll, 2008), in particular to a persisting pattern of cognitive impairments and enhanced impulsivity. However, there is so far no clarification on the exact relation between the use of cocaine and cognitive control in terms of cognitive functioning and impulsivity; Aetiology, causality, reversibility, and the extent of this association are still a matter of ongoing debate. The present doctoral thesis aims to contribute to this research gap and seeks to clarify the long-term relation between the use of cocaine on the one hand and cognitive functioning and impulsivity on the other hand. The clarification of this issue is important not only in regard to general functioning in daily life, but also in regard to risk markers, prevention, treatment, and after-treatment strategies. In the first paper (chapter 2), we examined whether cognitive performance is impaired in relatively pure recreational and dependent cocaine users. By means of a cross-sectional study, we compared the cognitive performance of 68 recreational and 30 dependent cocaine users with the performance of 68 stimulant-naïve controls. Whereas dependent cocaine users displayed broad cognitive impairments in the domains attention, working memory, declarative memory, and executive functions, recreational cocaine users performed in all four domains intermediate between controls and dependent users. Hence, cognitive deficits occur already at a recreational and non-dependent level of cocaine use. Moreover, correlation analyses revealed negative associations between the cognitive performance and long-term cocaine use parameters (cumulative dose, duration of use, hair metabolites) suggesting that cognitive impairments might be partially cocaine-induced. Accordingly, the risk for cognitive impairment was linked to ascending cumulative cocaine doses, in particular if estimated lifetime doses of 500g to 1000g cocaine were exceeded. Finally, an attention deficit hyperactivity disorder, craving, and age of onset proved to be important modulators of cognitive functioning in cocaine users. In the second paper (chapter 3), we used the same cross-sectional sample to examine trait and motor impulsivity in recreational and dependent cocaine users. Our goal was to clarify the role of impulse control in cocaine addiction and non-dependent cocaine use. Compared with controls, recreational and dependent cocaine users exhibited higher trait impulsivity and novelty seeking scores. Moreover, trait impulsivity scores correlated significantly with long-term cocaine intake parameters (cumulative dose, duration of use) and were strongly associated with symptoms of depression and attention deficit hyperactivity disorder. These findings suggest that increased trait impulsivity is not a specific feature of chronic cocaine use. By contrast, we found no associations between behavioral motor impulsivity measures and cocaine use parameters. However, it remains unclear if there is indeed a dissociation between trait and motor impulsivity or whether the differences rather highlight difficulties in the operationalization and measurement of motor impulsivity. In the third paper (chapter 4), we intended to determine the relation between the pattern of cocaine use and the characteristics of cognitive functioning by means of a 1-year longitudinal study including 57 cocaine users and 48 stimulant-naïve controls. Cognitive functioning was assessed by the same cognitive measures and domains as in the first paper. Our results suggest that substantially increased cocaine use within 1 year led to a deteriorated cognitive performance, primarily in the working memory. By contrast, decreased cocaine use generally improved cognition and showed the strongest enhancement in working and declarative memory, whereas users who completely ceased using cocaine seemed to recover entirely and attained a similar cognitive level as the control group. These results suggest that cognitive deficits are at least partially cocaine-induced but also reversible within 1 year. Seemingly, these cognitive changes in cocaine users are based on modifiable neuroplastic adaptations. However, these findings imply that abstinence is the best way to enhance cognitive performance in stimulant users in the long-run. Overall, these results indicate at strong relation between the repeated use of cocaine and specific characteristics of cognitive control. First, recreational and dependent cocaine users displayed cognitive impairment. Second, there is an evident relation between the long-term use of cocaine and cognitive functioning. Third, both, recreational and dependent cocaine users displayed enhanced trait impulsivity and novelty seeking. Fourth, there is a close relationship between the changing pattern of cocaine use and the development of cognitive functioning.

Abstract

The United Nations Office on Drugs and Crime currently estimates the annual number of cocaine users at about 17 million people worldwide, resulting in a total retail market of about 85 billion USD per year (2011; 2013). Although the use of cocaine is a widespread public health issue, there are still many open questions considering its concrete consequences. For now more than two decades, research has tried to examine the impact of cocaine use on cognition, primarily by focusing on dependent cocaine users. In recent years, the focus expanded to the more relevant type of recreational and non-dependent cocaine user (European Monitoring Center for Drugs and Drug Addiction, 2012). In this context, a growing body of literature consistently linked the longterm use of cocaine to different effects in cognitive control (Jovanovsky et al., 2005; Perry & Carroll, 2008), in particular to a persisting pattern of cognitive impairments and enhanced impulsivity. However, there is so far no clarification on the exact relation between the use of cocaine and cognitive control in terms of cognitive functioning and impulsivity; Aetiology, causality, reversibility, and the extent of this association are still a matter of ongoing debate. The present doctoral thesis aims to contribute to this research gap and seeks to clarify the long-term relation between the use of cocaine on the one hand and cognitive functioning and impulsivity on the other hand. The clarification of this issue is important not only in regard to general functioning in daily life, but also in regard to risk markers, prevention, treatment, and after-treatment strategies. In the first paper (chapter 2), we examined whether cognitive performance is impaired in relatively pure recreational and dependent cocaine users. By means of a cross-sectional study, we compared the cognitive performance of 68 recreational and 30 dependent cocaine users with the performance of 68 stimulant-naïve controls. Whereas dependent cocaine users displayed broad cognitive impairments in the domains attention, working memory, declarative memory, and executive functions, recreational cocaine users performed in all four domains intermediate between controls and dependent users. Hence, cognitive deficits occur already at a recreational and non-dependent level of cocaine use. Moreover, correlation analyses revealed negative associations between the cognitive performance and long-term cocaine use parameters (cumulative dose, duration of use, hair metabolites) suggesting that cognitive impairments might be partially cocaine-induced. Accordingly, the risk for cognitive impairment was linked to ascending cumulative cocaine doses, in particular if estimated lifetime doses of 500g to 1000g cocaine were exceeded. Finally, an attention deficit hyperactivity disorder, craving, and age of onset proved to be important modulators of cognitive functioning in cocaine users. In the second paper (chapter 3), we used the same cross-sectional sample to examine trait and motor impulsivity in recreational and dependent cocaine users. Our goal was to clarify the role of impulse control in cocaine addiction and non-dependent cocaine use. Compared with controls, recreational and dependent cocaine users exhibited higher trait impulsivity and novelty seeking scores. Moreover, trait impulsivity scores correlated significantly with long-term cocaine intake parameters (cumulative dose, duration of use) and were strongly associated with symptoms of depression and attention deficit hyperactivity disorder. These findings suggest that increased trait impulsivity is not a specific feature of chronic cocaine use. By contrast, we found no associations between behavioral motor impulsivity measures and cocaine use parameters. However, it remains unclear if there is indeed a dissociation between trait and motor impulsivity or whether the differences rather highlight difficulties in the operationalization and measurement of motor impulsivity. In the third paper (chapter 4), we intended to determine the relation between the pattern of cocaine use and the characteristics of cognitive functioning by means of a 1-year longitudinal study including 57 cocaine users and 48 stimulant-naïve controls. Cognitive functioning was assessed by the same cognitive measures and domains as in the first paper. Our results suggest that substantially increased cocaine use within 1 year led to a deteriorated cognitive performance, primarily in the working memory. By contrast, decreased cocaine use generally improved cognition and showed the strongest enhancement in working and declarative memory, whereas users who completely ceased using cocaine seemed to recover entirely and attained a similar cognitive level as the control group. These results suggest that cognitive deficits are at least partially cocaine-induced but also reversible within 1 year. Seemingly, these cognitive changes in cocaine users are based on modifiable neuroplastic adaptations. However, these findings imply that abstinence is the best way to enhance cognitive performance in stimulant users in the long-run. Overall, these results indicate at strong relation between the repeated use of cocaine and specific characteristics of cognitive control. First, recreational and dependent cocaine users displayed cognitive impairment. Second, there is an evident relation between the long-term use of cocaine and cognitive functioning. Third, both, recreational and dependent cocaine users displayed enhanced trait impulsivity and novelty seeking. Fourth, there is a close relationship between the changing pattern of cocaine use and the development of cognitive functioning.

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Additional indexing

Item Type:Dissertation
Referees:Quednow B B, Jäncke L
Communities & Collections:04 Faculty of Medicine > Psychiatric University Hospital Zurich > Clinic for Psychiatry, Psychotherapy, and Psychosomatics
06 Faculty of Arts > Institute of Psychology
Dewey Decimal Classification:150 Psychology
610 Medicine & health
Language:English
Date:August 2013
Deposited On:28 Jan 2014 13:15
Last Modified:05 Apr 2016 17:33

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