Psychopharmacology
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Randomized Controlled Trial
On-the-road driving performance after use of the antihistamines mequitazine and l-mequitazine, alone and with alcohol.
Previous studies demonstrated that mequitazine produces mild sedation after single doses. Its enantiomer, l-mequitazine, has a stronger potency for the H1 receptor. The aim of the current study was to assess the effects of l-mequitazine and mequitazine, alone and with alcohol, on driving. ⋯ L-mequitazine can be considered safe to drive in dosages of 2.5 and 5.0 mg. L-mequitazine 10 mg led to mild driving impairment. Alcohol impaired all performance measures and added to the effects of l-mequitazine and mequitazine.
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Ayahuasca is a South American psychotropic plant tea traditionally used in Amazonian shamanism. The tea contains the psychedelic 5-HT2A receptor agonist N,N-dimethyltryptamine (DMT), plus β-carboline alkaloids with monoamine oxidase-inhibiting properties. Increasing evidence from anecdotal reports and open-label studies indicates that ayahuasca may have therapeutic effects in treatment of substance use disorders and depression. A recent study on the psychological effects of ayahuasca found that the tea reduces judgmental processing and inner reactivity, classic goals of mindfulness psychotherapy. Another psychological facet that could potentially be targeted by ayahuasca is creative divergent thinking. This mode of thinking can enhance and strengthen psychological flexibility by allowing individuals to generate new and effective cognitive, emotional, and behavioral strategies. The present study aimed to assess the potential effects of ayahuasca on creative thinking. ⋯ The present data indicate that ayahuasca enhances creative divergent thinking. They suggest that ayahuasca increases psychological flexibility, which may facilitate psychotherapeutic interventions and support clinical trial initiatives.
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Gypenosides have been reported to produce neuroprotective effects and increase monoamine neurotransmitter levels in the brain. ⋯ This study demonstrates that gypenosides exhibit antidepressant-like effects in mice, which may be mediated by activation of the BDNF-ERK/Akt signaling pathway in the hippocampus.
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Self-titration is well documented in the tobacco literature. The extent to which e-cigarette users (vapers) self-titrate is unknown. ⋯ Vapers engaged in compensatory puffing with lower nicotine strength liquid, doubling their consumption. Whilst compensatory puffing was sufficient to reduce craving and withdrawal discomfort, self-titration was incomplete with significantly higher plasma nicotine levels in the high condition.
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Randomized Controlled Trial
Levodopa impairs probabilistic reversal learning in healthy young adults.
Dopaminergic therapy improves some cognitive functions and worsens others in patients with Parkinson's disease (PD). These paradoxical effects are explained by the dopamine overdose hypothesis, which proposes that effects of dopaminergic therapy on a cognitive function is determined by the baseline dopamine levels in brain regions mediating that function. ⋯ Exogenous dopamine impairs stimulus-reward learning, independent of PD pathology and prior to sensitization through repeated exposure, in healthy adults with normal cognition and baseline dopamine function. Our findings support the dopamine overdose hypothesis and caution clinicians about detrimental effects of levodopa in all clinical populations (e.g., early PD, restless leg syndrome) regardless of baseline cognitive and dopaminergic system function.