Trial reportDrug and alcohol dependence2013
Effects of tolcapone on working memory and brain activity in abstinent smokers: a proof-of-concept study.
Trial report in Drug and alcohol dependence, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
10 citing papers in PubMed, 1 synthesis or guideline pooled it, 15 citations in OpenAlex.
- Brain Structural Abnormalities in Addiction Disorders: Transdiagnostic Meta-Analyses.Human brain mapping · 2026Pooled it
- Effects of COMT Suppression in a Randomized Trial on the Neural Correlates of Inhibitory Processing Among People With Alcohol Use Disorder.Biological psychiatry. Cognitive neuroscience and neuroimaging · 2025Trial
- Effects of pharmacological and genetic regulation of COMT activity in alcohol use disorder: a randomized, placebo-controlled trial of tolcapone.Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2022Trial
- Catechol-O-Methyltransferase Effects on Smoking: A Review and Proof of Concept of Sex-Sensitive Effects.Current behavioral neuroscience reports · 2022Article
- A comparative study to assess general health status and oral health score of tobacco users and nonusers in geriatric population in central India.Journal of family medicine and primary care · 2020Article
- The Role of Working Memory for Cognitive Control in Anorexia Nervosa versus Substance Use Disorder.Frontiers in psychology · 2017Review
- COMT val158met moderation of dopaminergic drug effects on cognitive function: a critical review.The pharmacogenomics journal · 2016Review
- A reverse factual analysis of the association between smoking and memory decline in China.International journal for equity in health · 2016Article
- Effect of Pharmacological Interventions on the Fronto-Cingulo-Parietal Cognitive Control Network in Psychiatric Disorders: A Transdiagnostic Systematic Review of fMRI Studies.Frontiers in psychiatry · 2016Review
- Working memory-related neural activity predicts future smoking relapse.Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2015Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
9 authors at 2 institutions in 1 country.
Funding
Abstract
backgroundDopamine levels in the prefrontal cortex (PFC) are thought to play an important role in cognitive function and nicotine dependence. The catechol-O-methyltransferase (COMT) inhibitor tolcapone, an FDA-approved treatment for Parkinson's disease, increases prefrontal dopamine levels, with cognitive benefits that may vary by COMT genotype. We tested whether tolcapone alters working memory-related brain activity and performance in abstinent smokers.
methodsIn this double-blind crossover study, 20 smokers completed 8 days of treatment with tolcapone and placebo. In both medication periods, smokers completed blood oxygen level-dependent (BOLD) fMRI scans while performing a working memory N-back task after 24h of abstinence. Smokers were genotyped prospectively for the COMT val(158)met polymorphism for exploratory analysis.
resultsCompared to placebo, tolcapone modestly improved accuracy (p=0.017) and enhanced suppression of activation in the ventromedial prefrontal cortex (vmPFC) (p=0.002). There were no effects of medication in other a priori regions of interest (dorsolateral PFC, dorsal cingulate/medial prefrontal cortex, or posterior cingulate cortex). Exploratory analyses suggested that tolcapone led to a decrease in BOLD signal in several regions among smokers with val/val genotypes, but increased or remained unchanged among met allele carriers. Tolcapone did not attenuate craving, mood, or withdrawal symptoms compared to placebo.
conclusionsData from this proof-of-concept study do not provide strong support for further evaluation of COMT inhibitors as smoking cessation aids.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.