Markus R. Baumgartner

Cognitive dysfunctions in recreational and dependent cocaine users: role of attention-deficit hyperactivity disorder, craving and early age at onset

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.

Impaired emotional empathy and related social network deficits in cocaine users

Chronic cocaine users consistently display neurochemical and functional alterations in brain areas involved in social cognition (e.g. medial and orbitofrontal cortex). Although social functioning plays a crucial role in the development and treatment of drug dependence, studies investigating social cognition in cocaine users are lacking. Therefore, we investigated mental perspective taking (‘theory of mind’) and emotional and cognitive empathy in recreational (RCU) and dependent (DCU) cocaine users. Furthermore, we related these measures to real‐life indicators of social functioning. One‐hundred cocaine users (69 RCU, 31 DCU) and 68 stimulant‐naïve healthy controls were tested with the Multifaceted Empathy Test (MET), Movie for the Assessment of Social Cognition (MASC) and Reading the Mind in the Eyes Test (RMET). The Social Network Questionnaire was conducted to assess social network size. Furthermore, participants provided information on committed criminal offenses. RCU and DCU showed less emotional empathy compared to controls (MET), whereas cognitive empathy was not impaired (MET, RMET). Additionally, DCU made more errors in mental perspective taking (MASC). Notably, cocaine users committed more criminal offenses and displayed a smaller social network and higher cocaine use was correlated with less social contacts. Diminished mental perspective taking was tentatively correlated with more intense cocaine use as well. Finally, younger age of onset of cocaine use was associated with more pronounced empathy impairment. In conclusion, social cognition impairments in cocaine users were related to real‐life social functioning and should therefore be considered in therapy and prevention strategies.

Altered social and non-social decision-making in recreational and dependent cocaine users.

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.

Cognitive impairment in cocaine users is drug-induced but partially reversible: evidence from a longitudinal study.

Cocaine users consistently display cognitive impairments. However, it is still unknown whether these impairments are cocaine-induced and if they are reversible. Therefore, we examined the relation between changing intensity of cocaine use and the development of cognitive functioning within 1 year. The present data were collected as part of the longitudinal Zurich Cocaine Cognition Study (ZuCo2St). Forty-eight psychostimulant-naive controls and 57 cocaine users (19 with increased, 19 with decreased, and 19 with unchanged cocaine use) were eligible for analysis. At baseline and after a 1-year follow-up, cognitive performance was measured by a global cognitive index and four neuropsychological domains (attention, working memory, declarative memory, and executive functions), calculated from 13 parameters of a broad neuropsychological test battery. Intensity of cocaine use was objectively determined by quantitative 6-month hair toxicology at both test sessions. Substantially increased cocaine use within 1 year (mean +297%) was associated with reduced cognitive performance primarily in working memory. By contrast, decreased cocaine use (−72%) was linked to small cognitive improvements in all four domains. Importantly, users who ceased taking cocaine seemed to recover completely, attaining a cognitive performance level similar to that of the control group. However, recovery of working memory was correlated with age of onset of cocaine use—early-onset users showed hampered recovery. These longitudinal data suggest that cognitive impairment might be partially cocaine-induced but also reversible within 1 year, at least after moderate exposure. The reversibility indicates that neuroplastic adaptations underlie cognitive changes in cocaine users, which are potentially modifiable in psychotherapeutical or pharmacological interventions.

Differences in self-reported and behavioral measures of impulsivity in recreational and dependent cocaine users.

BACKGROUND Dependent cocaine users consistently display increased trait impulsivity on self-report questionnaires and less consistently exhibit elevated motor impulsivity in some behavioral tasks. However, trait and behavioral impulsivity measures have rarely been investigated in recreational users. Therefore, we examined self-reported trait and motor impulsivities in recreational and dependent cocaine users to clarify the role of impulse control in cocaine addiction and non-dependent cocaine use. METHODS We investigated relatively pure recreational (n=68) and dependent (n=30) cocaine users, as well as psychostimulant-naïve controls (n=68), with self-report questionnaires (Barratt Impulsiveness Scale 11; Temperament and Character Inventory) and behavioral tasks (Rapid Visual Information Processing Task; Stop-Signal Task). RESULTS Compared with controls, recreational and dependent cocaine users displayed higher trait impulsivity and novelty seeking scores on self-report questionnaires. Trait impulsivity scores were strongly associated with an increased number of symptoms of depression and attention deficit hyperactivity disorder and correlated significantly with long-term cocaine intake parameters. By contrast, none of the behavioral motor impulsivity measures showed significant group effects or correlated with cocaine use parameters. The correlations among the self-report measures were high, but self-reports were scarcely correlated with behavioral task measures. CONCLUSIONS These findings suggest that relatively pure cocaine users already display increased trait impulsivity at a recreational level of use. However, the results do not indicate any cocaine-related elevation of behavioral impulsivity in terms of motor or response inhibition. In summary, our data imply that elevated trait impulsivity is not a specific feature of dependent cocaine use.

Systematic investigation of the incorporation mechanisms of zolpidem in fingernails

Nails are attracting increasing interest in forensic toxicology as an alternative to hair. The goal of this study was to systematically investigate the incorporation of drugs in fingernails after single drug dose, exemplified for zolpidem. Fingernail samples from ring fingers were collected one week before, and then 24 h and weekly after intake for a period of three to five months. Hair samples were taken six weeks after intake. Nail specimens were pulverized and extracted with methanol (internal standard: zolpidem-D6 ) under sonication. Extracts were analyzed by a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method, which was developed and validated for this study. The lower limit of quantification (LLOQ) for a 5-mg sample was 0.1 pg/mg nail. Zolpidem was detected continuously in fingernail clippings. The mean window of detection of zolpidem in fingernail clippings was 3.5 months. Unwashed nail specimens taken 24 h after intake showed the highest zolpidem concentrations indicating external contamination by sweat. External contamination experiments revealed that zolpidem could be incorporated in fingernails by sweat to such an extent that it remained irremovable by daily hygiene. Averagely 3 months after intake a concentration peak was reached, suggesting outgrowth of the nail part which had been formed while the drug circulated in blood. Hair concentrations were higher than the maximum nail concentrations. Pigmented hair contained more zolpidem than non-pigmented hair from the same strand. From all these results it can be concluded, that fingernail clippings may represent a useful alternative and/or complementary matrix in cases of, for example, drug-facilitated sexual assault or monitoring of constant consumption behavior.

Increased Sensorimotor Gating in Recreational and Dependent Cocaine Users Is Modulated by Craving and Attention-Deficit/Hyperactivity Disorder Symptoms

BACKGROUND Cocaine dependence has been associated with blunted dopamine and norepinephrine signaling, but it is unknown if recreational cocaine use is also associated with alterations of catecholamine systems. Prepulse inhibition (PPI) of the acoustic startle response-a measure of sensorimotor gating-is highly sensitive for manipulations of the catecholamine system. Therefore, we investigated whether relatively pure recreational users (RCU) and dependent cocaine users (DCU) display alterations of PPI, startle reactivity, and habituation. Moreover, the influences of methylenedioxymethamphetamine and cannabis co-use, craving, and attention-deficit/hyperactivity disorder (ADHD) symptoms on startle measures were examined. METHODS In 64 RCU, 29 DCU, and 66 stimulant-naïve control subjects, PPI of acoustic startle response, startle reactivity, habituation, ADHD symptoms, and cocaine craving were assessed. Drug use of all participants was controlled by hair and urine toxicologies. RESULTS Both RCU and DCU showed increased PPI in comparison with control participants (Cohens d=.38 and d=.67, respectively), while RCU and DCU did not differ in PPI measures (d=.12). No significant group differences were found in startle reactivity or habituation measures. In cocaine users, PPI was positively correlated with cumulative cocaine dose used, craving for cocaine, and ADHD symptoms. Users with a diagnosis of ADHD and strong craving symptoms displayed the highest PPI levels compared with control subjects (d=.78). CONCLUSIONS The augmented PPI in RCU and DCU suggests that recreational use of cocaine is associated with altered catecholamine signaling, in particular if ADHD or craving symptoms are present. Finally, ADHD might be a critical risk factor for cocaine-induced changes of the catecholamine system.

Thermal degradation of copper(1) thiolate clusters and the crystal structure of solvent-free (Ph4P)2 [Cu4(SPh)6]

Abstract Copper(I) thiolate clusters of the type (Ph4P)2- [Cu4(SPh)6] or ((CH3)nN)2[Cux(SPh)y] with or without solvent molecules and with x:y = 4:6 or 5:7 have been crystallized from different solvents. Their thermal degradation behavior was characterized by thermogravimetry and simultaneous mass spectrometry of the evolved molecules. The solvent-containing complexes lose the solvent in a first decomposition step between 100 and 160 °C. The subsequent degradation is dependent on the cation only, not on the Cu(I)S core type and finally leads to Cu1.96S. In the course of this decomposition intermediate products with the stoichiometry Cux(SPh)x, are formed. The crystal structure of solvent-free (Ph4P)2- [Cu4(SPh)6] (a=23.290(9), b=13.008(4), c= 25.622(6) A, β=107.31(3)°, Z=4, space group P21/a) has been solved and refined to R=6.9% for 2982 observed reflections. The structure consists of adamantan-type [Cu4S6]2- clusters and Ph4P+ cations. The mean CuCu distance within the cluster is 2.744 A CuS distances range from 2.252 to 2.315 A. Crystals of ((CH3)4N)2[Cus(SPh)7] have been shown by thermal analysis to contain one solvent molecule per formula unit. The crystal structure of this solvent-containing complex (a=12.244(10), b=20.058(11), c=11.506(5) A, a=103.59(5), β= 90.04(5), γ=82.98(6)°, Z=2, space group P 1 , R= 6.1% including 3409 observed reflections) exhibits [Cu5(SPh7]2- clusters and (CH3)4N+ cations and shows no significant deviations from data given in the literature for the ‘olvent-free’ complex.

Segmental hair analysis for differentiation of tilidine intake from external contamination using LC‐ESI‐MS/MS and MALDI‐MS/MS imaging

Segmental hair analysis has been used for monitoring changes of consumption habit of drugs. Contamination from the environment or sweat might cause interpretative problems. For this reason, hair analysis results were compared in hair samples taken 24 h and 30 days after a single tilidine dose. The 24-h hair samples already showed high concentrations of tilidine and nortilidine. Analysis of wash water from sample preparation confirmed external contamination by sweat as reason. The 30-day hair samples were still positive for tilidine in all segments. Negative wash-water analysis proved incorporation from sweat into the hair matrix. Interpretation of a forensic case was requested where two children had been administered tilidine by their nanny and tilidine/nortilidine had been detected in all hair segments, possibly indicating multiple applications. Taking into consideration the results of the present study and of MALDI-MS imaging, a single application as cause for analytical results could no longer be excluded. Interpretation of consumption behaviour of tilidine based on segmental hair analysis has to be done with caution, even after typical wash procedures during sample preparation. External sweat contamination followed by incorporation into the hair matrix can mimic chronic intake. For assessment of external contamination, hair samples should not only be collected several weeks but also one to a few days after intake. MALDI-MS imaging of single hair can be a complementary tool for interpretation. Limitations for interpretation of segmental hair analysis shown here might also be applicable to drugs with comparable physicochemical and pharmacokinetic properties.

Single Hair Analysis of Small Molecules Using MALDI-Triple Quadrupole MS Imaging and LC-MS/MS: Investigations on Opportunities and Pitfalls

Single hair analysis normally requires extensive sample preparation microscale protocols including time-consuming steps like segmentation and extraction. Matrix assisted laser desorption and ionization mass spectrometric imaging (MALDI-MSI) was shown to be an alternative tool in single hair analysis, but still, questions remain. Therefore, an investigation of MALDI-MSI in single hair analysis concerning the extraction process, usage of internal standard (IS), and influences on the ionization processes were systematically investigated to enable the reliable application to hair analysis. Furthermore, single dose detection, quantitative correlation to a single hair, and hair strand LC-MS/MS results were performed, and the performance was compared to LC-MS/MS single hair monitoring. The MALDI process was shown to be independent from natural hair color and not influenced by the presence of melanin. Ionization was shown to be reproducible along and in between different hair samples. MALDI image intensities in single hair and hair snippets showed good semiquantitative correlation to zolpidem hair concentrations obtained from validated routine LC-MS/MS methods. MALDI-MSI is superior to LC-MS/MS analysis when a fast, easy, and cheap sample preparation is necessary, whereas LC-MS/MS showed higher sensitivity with the ability of single dose detection for zolpidem. MALDI-MSI and LC-MS/MS segmental single hair analysis showed good correlation, and both are suitable for consumption monitoring of drugs of abuse with a high time resolution.