Translational Psychiatry
April 8, 2021
Natasha L. Mason, Kim P. C. Kuypers, Johannes T. Reckweg et al.
132 citations
A double-blind, placebo-controlled experiment with 0.17 mg/kg psilocybin shows that the drug affects creative thinking in time-dependent and task-specific ways. Immediately after consumption, psilocybin increased spontaneous creative insights but decreased deliberate, task-based creativity. Seven days later, participants generated more novel ideas. Brain imaging revealed that both acute and persisting effects were predicted by connectivity within and between networks of the default mode network. These results support historical claims that psychedelics can influence aspects of the creative process and may serve as tools for investigating creativity and its neural basis.
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.
Addiction Biology
December 22, 2019
Natasha L. Mason, Eef L. Theunissen, Nadia R. P. W. Hutten et al.
58 citations
Regular cannabis users develop tolerance to the drug's impairing and rewarding effects, but the underlying brain changes are unclear. In a double-blind, placebo-controlled study, 12 occasional and 12 chronic cannabis users received acute doses of cannabis (300 μg/kg delta-9-tetrahydrocannabinol) or placebo. In occasional users, cannabis decreased functional connectivity and increased striatal glutamate levels in reward circuitry, linked to greater subjective high and worse attention performance. Chronic users showed none of these changes, indicating reduced responsiveness of reward circuitry to cannabis intoxication, suggesting a pharmacodynamic mechanism for tolerance development.
bioRxiv (Cold Spring Harbor Laboratory)
July 19, 2019
Natasha L. Mason, Eef L. Theunissen, Nadia R. P. W. Hutten et al.
4 citations
preprint
Regular cannabis users develop tolerance to the drug's impairing and rewarding effects, but the underlying brain changes are unclear. In a double-blind, randomized, placebo-controlled crossover study, 12 occasional and 12 chronic cannabis users received acute doses of cannabis (300 μg/kg THC) and placebo, then underwent ultra-high field fMRI and magnetic resonance spectroscopy. In occasional users, cannabis caused decreased functional connectivity and increased striatal glutamate concentrations in reward circuitry, linked to greater subjective high and worse sustained attention. These changes were absent in chronic users, suggesting reduced responsiveness of reward circuitry to cannabis intoxication and a pharmacodynamic mechanism for tolerance development.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology
December 1, 2019
Natasha L Mason, Eef L Theunissen, Nadia R P W Hutten et al.
THC increases striatal glutamate concentrations and reduces functional connectivity between the nucleus accumbens and cortical areas, indicating increased dopaminergic activity. These changes were dose dependent, occurring in the full dose group where THC serum concentrations exceeded 2 ng/ml at T-max. Average glutamate changes correlated strongly with functional connectivity alterations. THC-induced changes in functional connectivity correlated with feelings of subjective high and decreased performance on an attention task. The findings suggest THC elicits subjective and cognitive alterations via increased striatal dopaminergic activity and loss of corticostriatal connectivity, associated with increased striatal glutamate.