Have you ever wondered what motivates an individual to use cannabis? Is it a psychological want or physiological need? To begin, cannabis has become the most widely used illicit substance in the world. The drug is used by many, in many places; whether that be for medical or recreational purposes. The frontostriatolimbic region mainly contains the dorsal and ventral striata, that are linked with reward, learning, and cognitive control. Research has shown that frequent use of cannabis has been linked to maladaptations in these regions which may be linked to the transition of addiction in the brain.

Addiction is a chronic brain disorder in which the person may relapse repeatedly. Drug addiction is characterized by loss of control over behavior and drug usage, as well as an overwhelming desire to take the drug, especially when deprived or when exposed to certain cues associated with drug usage. Consider the individual who is trying to go on a diet. Their diet may be better maintained if they are not exposed to their favorite dessert. In comparison, for an individual who is attempting to quit using cannabis; their ability to quit would be better maintained if they were not exposed to the drug.

The purpose of this study was to test cue reactivity in our physiologic reward and decision-making systems associated with addiction, and how they are affected by the use of cannabis. The study by Zhou et al. (2019) involved the use of dependent and non-dependent cannabis users (determined by criteria in the Diagnostic and Statistical Manual of Mental Disorders, DSM-IV) and how behavioral and neural cue reactivity on different brain areas affected these individuals. The striatal area of the forebrain contains the dorsal and ventral striatal regions. The ventral region, is mainly involved in reward processing, incentive-based learning, and impulsiveness. The dorsal region is mainly involved in habit formation, regulatory control, and compulsiveness. In previous studies involving animals, it was shown that the transition from recreational to compulsive drug use is mediated by a conversion in control of behavior from ventral to dorsal. With this, drug addiction may be caused by this transition to frequent/compulsive use or by individual differences in traits associated with variations in striatal functioning, specifically the impulsiveness trait associated with the ventral striatum.

Behavioral and neural cues were used in dependent and non-dependent users. These cues have been thought to elicit motivational and compulsive striatal responses associated with addiction. The researchers hypothesized that both groups of cannabis users (dependent and non-dependent) in response to cannabis cues, would show exaggerated ventral striatal activity along with impulsive behavior while dependent users would also show dorsal striatal cue reactivity. This hypothesis rang true due to the ventral striatum being strongly engaged in signaling reward and anticipation for certain events as well as associated decision making and impulsiveness when paired with drug cues.

With the use of Magnetic Resonance Imaging (MRI), it was also found that cannabis users, whether recreational or dependent, showed increased impulsivity in response to drug cues. These cues also caused an increase in arousal and craving. In other words, by being exposed to objects, events, or people that one would associate with cannabis, that individual would be more motivated toward the substance and toward deliberately using the substance.

The results of this study showed that there is a neural basis involved in the transition to addiction in association with drug related cues in both types of cannabis users.

Reference:

Zhou, X., Zimmermann, K., Xin, F., Zhao, W., Derckx, R. T., Sassmannshausen, A., … & Becker, B. (2019). Cue Reactivity in the Ventral Striatum Characterizes Heavy Cannabis Use, Whereas Reactivity in the Dorsal Striatum Mediates Dependent Use. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 4(8), 751-762.