Dimitar Nedelchev
D. Nedelchev1, E. Psederska1,2, K. Bozgunov1, G. Vasilev1, J. Vassileva3. 1Bulgarian Addictions Institute, Sofia, Bulgaria; 2New Bulgarian University, Sofia, Bulgaria; 3Virginia Commonwealth University, Richmond VA, United States
Background: Research suggests that different drug classes such as opiates and stimulants are associated with specific neurocognitive and personality manifestations; however, most studies have been based on polysubstance users and our understanding of these functions in single drug users remain limited. The aim of the current study was to investigate differences between individuals with mono-dependence on either opiates/heroin or stimulants/amphetamines and individuals with polysubstance dependence on several neuropsychological, personality and psychiatric measures commonly associated with addictions.
Method: We tested 602 individuals (123 mono-dependent heroin users; 113 mono-dependent amphetamine users; 150 polysubstance dependent users and 216 non-substance dependent controls) with measures of neurocognitive functioning (Cambridge Gambling Task; Iowa Gambling Task; Balloon Analogue Risk Task; Immediate Memory Task; Delayed Reward Discounting Task; Go/No-go task; Stop Signal Task), externalizing (antisocial personality disorder [ASPD], psychopathy, ADHD, sensation seeking, impulsivity) and internalizing (anxiety, anxiety sensitivity, depression, alexithymia) traits. The majority of substance dependent participants (68%) were in protracted abstinence (> 1 year) at the time of testing.
Results: Neurocognitive results reveal that mono-dependent heroin users had higher delay aversion than controls on the Cambridge Gambling Task; however, there were no differences between poly- and mono-substance dependent users in this domain. On externalizing measures, polysubstance users had higher levels of aggression than mono-dependent heroin and amphetamine users; higher levels of ADHD, antisocial personality disorder, and psychopathy than mono-dependent amphetamine users; and higher levels of trait impulsivity and sensation seeking than mono-dependent heroin users. Among the two mono-dependent groups, amphetamine users had higher sensation seeking and trait impulsivity than heroin users, whereas heroin users endorsed more symptoms of ASPD and psychopathy than amphetamine users. On internalizing measures, polysubstance users had higher levels of depression, anxiety, and alexithymia than amphetamine but not heroin users.
Conclusions: Our findings suggest that polysubstance dependence is characterized by higher externalizing & internalizing symptoms than mono-dependence on opiates or stimulants. In addition, results reveal important differences between mono-dependence on heroin vs. amphetamines, with antisocial/psychopathic traits being specific to heroin dependence, and impulsive/sensation-seeking traits being specific to amphetamine dependence. Notably, there were no differences in neurocognitive function between polysubstance and mono-substance dependent individuals, which could reflect recovery of function with protracted abstinence.
Acknowledgements: This research was supported by grant R01 DA021421 from the National Institute of Drug Abuse (NIDA) and the Fogarty International Center (FIC) to Jasmin Vassileva.