Substance Abuse Faculty
Thomas Crowley, MD
I. Conduct and substance abuse problems and risk-taking: the chicken egg issue
“Risky behaviors” are those in which consequences may be, unpredictably, either reinforcing or punishing. Lane et al (2004) offer this operational definition: (a) a choice is made between 2 or more response options when (b) one of those options has some probability (greater than 0) to produce on any given occasion either a reinforcing or an aversive consequence, and (c) the probability of that consequence is unknown when the risky option is chosen.
There are three reasons to study such risk-taking behavior as a consequence of adolescent substance use: (1) Among substance-dependent youths risk-taking leads to, e.g., disease, pregnancy, or arrest. (2) Abused substances may exacerbate risk-taking in animals (Cook, Davidson 1973). (3) Extensive substance use itself is a risky behavior, producing uncertain rewards by activating a brain reward system (Gardner 2000), but also such punishments as, e.g.,arrests, school expulsions, psychotic thinking, seizures, cerebrovascular abnormalities, compulsive drug-seeking, or withdrawal (APA 2000).
Risk-taking is a central characteristic of CD. Many of the defining behaviors of CD and ASPD are risk-taking behaviors (stealing, fire-setting, break-ins, truancy, reckless disregard for safety, etc.). Patients describe them as exciting, but doing those things suggests considerable disregard for potential aversive consequences. For example, early-onset sexual intercourse, which may have major adverse consequences, is much more common among adolescent girls with CD than among others (Marmorstein, Iacono 2001). Risk-taking is part of the “behavioral disinhibition” that is so important in comorbid SCP (Young et al 2000; Iacono et al 1999). Indeed, in laboratory tests even abstinent adults and adolescents with conduct and substance problems, take more risks than others (Lane, Cherek 2000, 2001).
Greater risk-taking may set the stage for substance involvement, but substances themselves induce greater risk-taking. Intoxication with the substances most used by these patients, alcohol and marijuana, significantly increases risk-taking in a standardized laboratory test (Lane et al 2004, 2005). Does chronic substance exposure (beyond acute intoxication) also alter risky decision-making? The question is highlighted in a recent study comparing college students who did, or did not, use stimulant drugs (Leland, Paulus 2005). Although all were abstinent when performing a laboratory test of risk-taking, the users took more risks. Was that because of antecedent, impulsive, risk-taking traits that actually had contributed to the stimulant use, or did the substance use alter risky decision-making, or both?
Dr Crowley and group have developed an event related task called the Modified Balloon Game (MBG) to measure risk taking in patients. Several versions of this task were tested during pilot runs in the 3T magnet and were concluded with two 17 year-old male patients with serious “serious substance and conduct problems” (SCP). The exciting preliminary data are as follows:
This exciting feasibility data shows that with the modified balloon game (MBG) an event-related design it is possible to distinguish different brain regions that activate in the processing of decision-making (involving risk), reward, and punishment.