Scientific Reports
May 26, 2016
Johannes G. Ramaekers, J. H. van Wel, Desirée Spronk et al.
81 citations
Acute cannabis intoxication impairs executive function, impulse control, attention, and psychomotor function, and increases subjective intoxication, regardless of how frequently a person uses cannabis. In a study of 122 drug users with cannabis use histories ranging from infrequent to daily, cannabis (300 μg/kg THC) produced these deficits compared to placebo, while cocaine (300 mg) improved psychomotor function and attention but impaired impulse control. The absence of tolerance to cannabis's neurocognitive effects suggests that frequent use and intoxication can interfere with performance in daily environments such as school, work, or traffic.
Brain Imaging and Behavior
December 14, 2015
Johannes G. Ramaekers, J. H. van Wel, Desirée Spronk et al.
61 citations
The dopamine β-hydroxylase (DβH) enzyme converts dopamine into noradrenaline. People with low-activity DBH genotypes (rs1611115 CT/TT) appear more sensitive to cannabis and cocaine's effects on cognitive impulse control and brain connectivity. In 122 regular drug users, acute doses of cannabis (450 μg/kg THC) and cocaine (300 mg) increased cognitive impulsivity and reduced functional connectivity between the nucleus accumbens and limbic, prefrontal, striatal, and thalamic areas, primarily in those with CT/TT genotypes, not in those with the CC genotype. A negative association emerged between impulsivity and subcortical connectivity. The findings suggest DBH genotype influences how these drugs affect impulse control and brain networks, potentially explaining progression to drug seeking and informing targeted pharmacotherapy.
British Journal of Pharmacology
October 11, 2013
Janelle H. P. van Wel, Kim P. C. Kuypers, Eef L. Theunissen et al.
38 citations
Heavy cannabis users show broad impairments in neuropsychological function during THC intoxication, including reduced psychomotor performance and more errors on impulsivity tasks. These impairments appear less severe in psychomotor tasks than those previously seen in occasional users, suggesting some tolerance. Cocaine temporarily improves psychomotor function and speeds reaction times but increases errors, indicating a trade-off between stimulation and impulse control. The decline in impulse control may increase the risk of repeated drug use and addiction.
Drug and alcohol dependence
September 12, 2025
Matthijs Blankers, Ruben Van Beek, Desirée Spronk et al.
1 citation
In the three days after using ecstasy/MDMA, young adults who regularly use the drug report a small but significant drop in mental well-being, even after accounting for other substance use, sleep, and baseline depression or anxiety. Cocaine co-use and poor sleep further worsened the effect. No similar drop was seen after use of other common substances. The findings suggest the post-acute mood decline is specifically linked to ecstasy/MDMA, not just party or lifestyle factors.