Janna Cousijn

I am a scientist with an interdisciplinary background in neurobiology, medicine and psychology. An intriguing question central to all my studies is why only some individuals develop an addiction after heavy substance use. I thereby study the interaction between motivational processes (reward, emotions) and cognitive control in the brain. I received my Doctorate Cum Laude (awarded <5%) for identifying predictors of cannabis dependence with a novel combination of neuroimaging techniques (structural MRI, functional MRI, connectivity analyses) and neuropsychological tasks applied to a large group of difficult to find cannabis users and closely matched controls. After finishing by PhD, I became a postdoc at Leiden University where I extended my knowledge on the study of atypical brain development in the context of mental disorders. In 2014 I moved to Utrecht University to work as an Associate Research Scientist responsible for theory development, study design and supervision of PhD students in a prestigious large-scale (6000 children) 10-year longitudinal neuroimaging study on atypical brain development (NWO Zwaartekracht). Recently, I was invited back at the University of Amsterdam as an assistant professor (Tenure) in Clinical Developmental Neuroscience.

Contribution to Science

Partly due to the ongoing discussion regarding the addictive potential of cannabis, compared to other substances of abuse, relatively little is known about the brain processes underlying regular cannabis use and dependence. An estimated 10 percent of the weekly cannabis users will develop a dependency. From both a fundamental and clinical perspective, it is crucial to delineate the effects of regular cannabis use versus cannabis dependence on brain and behavior. The overarching goal of my research is to fill this knowledge gap. I thereby made great progress 1) unraveling the neurobiology underlying cannabis dependence and 2) identifying predictors of the course of cannabis dependence, and 3) testing the validity and clinical value of our laboratory measures in different real-life settings, including treatment.

1) Neurobiology underlying cannabis use versus dependence. I have conducted several studies investigating brain structure, function and behavior in regular and dependent cannabis users. My results imply that motivational processes like craving, approach-bias and attentional-bias are already evident in regular cannabis users. In contrast, cognitive control deficits and malfunctioning of the underlying brain systems may only occur in those cannabis users whom are dependent, covarying with the severity of the cannabis use-related problems. My work thereby profiled brain structure and function in cannabis user with and without problems, fostering a well informed and balanced view on the effects of cannabis use and dependence on the brain.

2) Predictors of the course of cannabis dependence. Using different neuropsychological tasks and MRI techniques, I studied the predictive association between brain function and future cannabis use is clinical and subclinical populations. I thereby revealed that both motivational (e.g., approach-bias, craving) and control (working-memory) related processes can predict the escalation of cannabis use towards dependence, and relapse after treatment. I embrace a multimodal approach, combining and comparing behavioral, self-reported and neural measures. Importantly, the results showed that neural measures explained unique variance in future cannabis use, on top of more simpler and cheaper behavioral measures.

3) Mechanisms underlying approach-bias: from neuroscience to treatment. The automatic tendency to approach drugs (i.e., approach-bias) shows great potency as a predictor of problematic drug use and as a target for treatment. However, little is known about the underlying mechanisms. Through studies investigating the expression of approach-bias within different contexts (e.g., real-life, laboratory and clinical settings, emotional context) I advanced the knowledge on the underlying behavioral and neural mechanisms. In collaboration with multiple international research groups I successfully studied the mechanisms of chance underlying approach-bias retraining in different drug-using populations to unravel for whom the training works.