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Doss MK, de Wit H, Gallo DA. The acute effects of psychoactive drugs on emotional episodic memory encoding, consolidation, and retrieval: A comprehensive review. Neurosci Biobehav Rev 2023; 150:105188. [PMID: 37085021 PMCID: PMC10247427 DOI: 10.1016/j.neubiorev.2023.105188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 04/23/2023]
Abstract
Psychoactive drugs modulate learning and emotional processes in ways that could impact their recreational and medical use. Recent work has revealed how drugs impact different stages of processing emotional episodic memories, specifically encoding (forming memories), consolidation (stabilizing memories), and retrieval (accessing memories). Drugs administered before encoding may preferentially impair (e.g., GABAA sedatives including alcohol and benzodiazepines, Δ9-tetrahydrocannabinol or THC, ketamine), enhance (e.g., dextroamphetamine and dextromethamphetamine), or both impair and enhance (i.e., ± 3,4-methylenedioxymethylamphetamine or MDMA) emotionally negative and positive compared to neutral memories. GABAA sedatives administered immediately post-encoding (during consolidation) can preferentially enhance emotional memories, though this selectivity may decline or even reverse (i.e., preferential enhancement of neutral memories) as the delay between encoding and retrieval increases. Finally, retrieving memories under the effects of THC, dextroamphetamine, MDMA, and perhaps GABAA sedatives distorts memory, with potentially greater selectively for emotional (especially positive) memories. We review these effects, propose neural mechanisms, discuss methodological considerations for future work, and speculate how drug effects on emotional episodic memory may contribute to drug use and abuse.
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Affiliation(s)
- Manoj K Doss
- Department of Psychiatry and Behavioral Sciences, Center for Psychedelic & Consciousness Research, USA.
| | - Harriet de Wit
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, USA
| | - David A Gallo
- Department of Psychology, University of Chicago, USA
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Faßbender K, Bey K, Lippold JV, Aslan B, Hurlemann R, Ettinger U. GABAergic modulation of performance in response inhibition and interference control tasks. J Psychopharmacol 2021; 35:1496-1509. [PMID: 34278874 DOI: 10.1177/02698811211032440] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Inhibitory control is a crucial executive function with high relevance to mental and physical well-being. However, there are still unanswered questions regarding its neural mechanisms, including the role of the major inhibitory neurotransmitter, γ-aminobutyric acid (GABA). AIMS This study examined the effects of lorazepam (0.5 mg and 1 mg), a positive allosteric modulator at the GABAA receptor, on response inhibition and interference control. We also explored the heterogeneity of inhibitory control and calculated delta plots to explore whether lorazepam affects the gradual build-up of inhibition and activation over time. METHODS N = 50 healthy participants performed antisaccade, Eriksen flanker and Simon tasks in a within-subjects, placebo-controlled, double-blind randomized design. RESULTS Lorazepam increased reaction time (RT) and error rates dose dependently in all tasks (p ⩽ 0.005). In the antisaccade and Simon tasks, lorazepam increased congruency effects for error rate (p ⩽ 0.029) but not RT (p ⩾ 0.587). In the Eriksen flanker task, both congruency effects were increased by the drug (p ⩽ 0.031). Delta plots did not reflect drug-induced changes in inhibition and activation over time. Delta plots for RT in the Simon task were negative-going, as expected, whereas those for the antisaccade and flanker tasks were positive-going. CONCLUSIONS This study provides evidence for GABAergic involvement in performance on response inhibition and interference control tasks. Furthermore, our findings highlight the diversity of the broader construct of inhibitory control while also pointing out similarities between different inhibitory control tasks. In contrast to RT and error rates, the cognitive processes indexed by delta plots may not be sensitive to GABAergic modulation.
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Affiliation(s)
- Kaja Faßbender
- Department of Psychology, University of Bonn, Bonn, Germany
| | - Katharina Bey
- Department of Psychiatry and Psychotherapy, University of Bonn, Bonn, Germany
| | | | - Behrem Aslan
- Department of Psychiatry and Psychotherapy, University of Bonn, Bonn, Germany
| | - René Hurlemann
- Department of Psychiatry, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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Abstract
Nootropics are drugs used to either treat or benefit cognition deficits. Among this class, methylphenidate is a popular agent, which acts through indirect dopaminergic and noradrenergic agonism and, therefore, is proposed to enhance performance in catecholamine-dependent cognitive domains such as attention, memory and prefrontal cortex-dependent executive functions. However, investigation into the efficacy of methylphenidate as a cognitive enhancer has yielded variable results across all domains, leading to debate within the scientific community surrounding its off-label use in healthy individuals seeking scholaristic benefit or increased productivity. Through analysis of experimental data and methodological evaluation, it is apparent that there are dose-, task- and domain-dependent considerations surrounding the use of methylphenidate in healthy individuals, whereby tailored dose administration is likely to provide benefit on an individual basis dependent on the domain of cognition in which benefit is required. Additionally, it is apparent that there are subjective effects of methylphenidate, which may increase user productivity irrespective of cognitive benefit. Whilst there is not extensive study in healthy older adults, it is plausible that there are dose-dependent benefits to methylphenidate in older adults in selective cognitive domains that might improve quality of life and reduce fall risk. Methylphenidate appears to produce dose-dependent benefits to individuals with attention-deficit/hyperactivity disorder, but the evidence for benefit in Parkinson's disease and schizophrenia is inconclusive. As with any off-label use of pharmacological agents, and especially regarding drugs with neuromodulatory effects, there are inherent safety concerns; epidemiological and experimental evidence suggests there are sympathomimetic, cardiovascular and addictive considerations, which might further restrict their use within certain demographics.
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Roberts CA, Jones A, Sumnall H, Gage SH, Montgomery C. How effective are pharmaceuticals for cognitive enhancement in healthy adults? A series of meta-analyses of cognitive performance during acute administration of modafinil, methylphenidate and D-amphetamine. Eur Neuropsychopharmacol 2020; 38:40-62. [PMID: 32709551 DOI: 10.1016/j.euroneuro.2020.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/11/2020] [Accepted: 07/06/2020] [Indexed: 12/20/2022]
Abstract
Modafinil, methyphenidate (MPH) and d-amphetamine (d-amph) are putative cognitive enhancers. However, efficacy of cognitive enhancement has yet to be fully established. We examined cognitive performance in healthy non-sleep-deprived adults following modafinil, MPH, or d-amph vs placebo in 3 meta-analyses, using subgroup analysis by cognitive domain; executive functions (updating, switching, inhibitory control, access to semantic/long term memory), spatial working memory, recall, selective attention, and sustained attention. We adhered to PRISMA. We identified k = 47 studies for analysis; k = 14 studies (64 effect sizes) for modafinil, k = 24 studies (47 effect sizes) for Methylphenidate, and k = 10 (27 effect sizes) for d-amph. There was an overall effect of modafinil (SMD=0.12, p=.01). Modafinil improved memory updating (SMD=0.28, p=.03). There was an overall effect of MPH (SMD=0.21, p=.0004) driven by improvements in recall (SMD=0.43, p=.0002), sustained attention (SMD=0.42, p=.0004), and inhibitory control (SMD=0.27, p=.03). There were no effects for d-amph. MPH and modafinil show enhancing effects in specific sub-domains of cognition. However, data with these stimulants is far from positive if we consider that effects are small, in experiments that do not accurately reflect their actual use in the wider population. There is a user perception that these drugs are effective cognitive enhancers, but this is not supported by the evidence so far.
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Affiliation(s)
- Carl A Roberts
- Department of Psychological Sciences, University of Liverpool, United Kingdom.
| | - Andrew Jones
- Department of Psychological Sciences, University of Liverpool, United Kingdom
| | - Harry Sumnall
- Public Health Institute, Liverpool John Moores University, Liverpool, United Kingdom
| | - Suzanne H Gage
- Department of Psychological Sciences, University of Liverpool, United Kingdom
| | - Catharine Montgomery
- Department of Psychology, John Moores Liverpool University, Liverpool, United Kingdom
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Conrad EC, Humphries S, Chatterjee A. Attitudes Toward Cognitive Enhancement: The Role of Metaphor and Context. AJOB Neurosci 2019; 10:35-47. [PMID: 31070552 DOI: 10.1080/21507740.2019.1595771] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The widespread use of stimulants among healthy individuals to improve cognition has received growing attention; however, public attitudes toward this practice are not well understood. We determined the effect of framing metaphors and context of use on public opinion toward cognitive enhancement. We recruited 3,727 participants from the United States to complete three surveys using Amazon's Mechanical Turk between April and July 2017. Participants read vignettes describing an individual using cognitive enhancement, varying framing metaphors (fuel versus steroid), and context of use (athletes versus students versus employees). The main outcome measure was the difference in respondent-assigned level of acceptability of the use of cognitive enhancement by others and by themselves between the contrasting vignettes. Participants were more likely to support the use of cognitive enhancement by others than by themselves and more when the use of enhancement by others was framed with a fuel metaphor than with a steroid metaphor. Metaphoric framing did not affect participants' attitudes toward their own use. Participants supported the use of enhancement by employees more than by students or athletes. These results are discussed in relation to existing ethical and policy literature.
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Doss MK, Weafer J, Ruiz NA, Gallo DA, De Wit H. Alcohol and pharmacologically similar sedatives impair encoding and facilitate consolidation of both recollection and familiarity in episodic memory. Cogn Neurosci 2018; 9:89-99. [PMID: 30044718 DOI: 10.1080/17588928.2018.1504764] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Alcohol and other pharmacologically similar sedatives (i.e., GABAA positive allosteric modulators or PAMs) impair the encoding of new episodic memories but retroactively facilitate the consolidation of recently encoded memories. These effects are consistent for recollection (i.e., the retrieval of details) but some mixed results have been reported for familiarity (i.e., a feeling of knowing a stimulus was presented). Here, with dual-process models, we reanalyzed prior work testing the effects of GABAA PAMs at encoding or consolidation. Contrary to previous conclusions, we show that GABAA PAMs at encoding consistently impair both recollection and familiarity when an independence correction is applied to familiarity-based responses. These findings were further confirmed and extended in a dual-process signal detection analysis of a recent study on the effects of alcohol during encoding or consolidation: Alcohol at encoding impaired both recollection and familiarity, whereas alcohol at consolidation enhanced both recollection and familiarity. These findings speak to the ability of alcohol and other GABAA PAMs to induce 'blackouts,' highlighting the importance of dual-process approaches when analyzing drug manipulations at different phases of episodic memory.
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Affiliation(s)
- Manoj K Doss
- a Department of Psychology , The University of Chicago , Chicago , IL , USA
| | - Jessica Weafer
- b Department of Psychiatry and Behavioral Neuroscience , The University of Chicago , Chicago , IL , USA
| | - Nicholas A Ruiz
- b Department of Psychiatry and Behavioral Neuroscience , The University of Chicago , Chicago , IL , USA
| | - David A Gallo
- a Department of Psychology , The University of Chicago , Chicago , IL , USA
| | - Harriet De Wit
- b Department of Psychiatry and Behavioral Neuroscience , The University of Chicago , Chicago , IL , USA
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Amodeo LR, Jacobs-Brichford E, McMurray MS, Roitman JD. Acute and long-term effects of adolescent methylphenidate on decision-making and dopamine receptor mRNA expression in the orbitofrontal cortex. Behav Brain Res 2017; 324:100-108. [PMID: 28212944 DOI: 10.1016/j.bbr.2017.02.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 02/01/2017] [Accepted: 02/11/2017] [Indexed: 01/09/2023]
Abstract
Though commonly used as a treatment for ADHD, the psychostimulant methylphenidate (MPH) is also misused and abused in adolescence in both clinical and general populations. Although MPH acts via pathways activated by other drugs of abuse, the short- and long-term effects of MPH on reward processing in learning and decision-making are not clearly understood. We examined the effect of adolescent MPH treatment on a battery of reward-directed behaviors both in adolescence during its administration and in adulthood after its discontinuation. We further measured whether MPH had lasting effects on dopamine receptor mRNA expression in orbitofrontal cortex (OFC) that may correspond with behavior. Long-Evans rats were injected with MPH (0, 1, 2.5, or 5mg/kg IP) twice daily from middle to late adolescence (PD38-57). During adolescence, the high dose of MPH reduced preference for large rewards in a Reward Magnitude Discrimination task, but did not affect preference for smaller-sooner rewards in a Delay Discounting task. In adulthood, after discontinuation of MPH, animals previously treated with the moderate dose of MPH showed improved acquisition, but not reversal, in a Reversal Learning task. MPH exposure did not increase preference for large-risky rewards in a Risk task in adulthood. We then quantified mRNA expression of D1, D2, and D3 receptors in the OFC using qPCR. MPH increased mRNA expression of dopamine D3 receptor subtype, but not D1 or D2. Overall, these results indicate that MPH has both immediate and lasting effects on reward-dependent learning and decisions, as well as dopaminergic function in rodents.
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Affiliation(s)
- Leslie R Amodeo
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Eliza Jacobs-Brichford
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Matthew S McMurray
- Department of Psychology, Miami University, 90 N Patterson Ave, Oxford, OH 45056, USA
| | - Jamie D Roitman
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA; Laboratory of Integrative Neuroscience, University of Illinois at Chicago,1007 West Harrison Street, Chicago, IL 60607, USA.
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Batistela S, Bueno OFA, Vaz LJ, Galduróz JCF. Methylphenidate as a cognitive enhancer in healthy young people. Dement Neuropsychol 2016; 10:134-142. [PMID: 29213444 PMCID: PMC5642404 DOI: 10.1590/s1980-5764-2016dn1002009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The so-called cognitive enhancers have been widely and increasingly used by healthy individuals who seek improvements in cognitive performance despite having no pathologies. One drug used for this purpose is methylphenidate, a first-line drug for the treatment of attention deficit hyperactivity disorder (ADHD). Objective The aim of the present study was to test the effect of acute administration of varying doses of methylphenidate (10 mg, 20 mg, 40 mg and placebo) on a wide range of cognitive functions in healthy young people. Methods A total of 36 young university students and graduates participated in the study. The participants underwent tests of attention and of episodic, and working memory. Results No differences in performance were observed on any of the tests. There was a dose-dependent (40 mg > placebo) effect on self-reported wellbeing. Conclusions According to the recent literature, psychostimulant medications, such as methylphenidate, improve performance when cognitive processes are below an optimal level, which was not the case for the subjects of the present study. We suggest the impression that methylphenidate enhances cognitive performance in healthy young people, justifying its use, may be due to improvements in subjective wellbeing promoted by the drug.
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Affiliation(s)
- Silmara Batistela
- MS, Departamento de Psicobiologia - Universidade Federal de São Paulo, São Paulo SP, Brazil
| | | | - Leonardo José Vaz
- PhD,Departamento de Psicobiologia - Universidade Federal de São Paulo, São Paulo SP, Brazil
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Kline RL, Zhang S, Farr OM, Hu S, Zaborszky L, Samanez-Larkin GR, Li CSR. The Effects of Methylphenidate on Resting-State Functional Connectivity of the Basal Nucleus of Meynert, Locus Coeruleus, and Ventral Tegmental Area in Healthy Adults. Front Hum Neurosci 2016; 10:149. [PMID: 27148006 PMCID: PMC4834346 DOI: 10.3389/fnhum.2016.00149] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/24/2016] [Indexed: 12/12/2022] Open
Abstract
Background: Methylphenidate (MPH) influences catecholaminergic signaling. Extant work examined the effects of MPH on the neural circuits of attention and cognitive control, but few studies have investigated the effect of MPH on the brain's resting-state functional connectivity (rsFC). Methods: In this observational study, we compared rsFC of a group of 24 healthy adults who were administered an oral 45 mg dose of MPH with a group of 24 age and gender matched controls who did not receive MPH. We focused on three seed regions: basal nucleus of Meynert (BNM), locus coeruleus (LC), and ventral tegmental area/substantia nigra, pars compacta (VTA/SNc), each providing cholinergic, noradrenergic and dopaminergic inputs to the cerebral cortex. Images were pre-processed and analyzed as in our recent work (Li et al., 2014; Zhang et al., 2015). We used one-sample t-test to characterize group-specific rsFC of each seed region and two-sample t-test to compare rsFC between groups. Results: MPH reversed negative connectivity between BNM and precentral gyri. MPH reduced positive connectivity between LC and cerebellum, and induced positive connectivity between LC and right hippocampus. MPH decreased positive VTA/SNc connectivity to the cerebellum and putamen, and reduced negative connectivity to left middle occipital gyrus. Conclusion: MPH had distinct effects on the rsFC of BNM, LC, and VTA/SNc in healthy adults. These new findings may further our understanding of the role of catecholaminergic signaling in Attention Deficit Hyperactivity Disorder (ADHD) and Parkinson's disease and provide insights into the therapeutic mechanisms of MPH in the treatment of clinical conditions that implicate catecholaminergic dysfunction.
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Affiliation(s)
- Ryan L Kline
- Department of Psychology, Yale University School of Arts and Sciences New Haven, CT, USA
| | - Sheng Zhang
- Department of Psychiatry, Yale University School of Medicine New Haven, CT, USA
| | - Olivia M Farr
- Interdepartmental Neuroscience Program, Yale University New Haven, CT, USA
| | - Sien Hu
- Department of Psychiatry, Yale University School of Medicine New Haven, CT, USA
| | - Laszlo Zaborszky
- Center for Molecular and Behavioral Neuroscience Rutgers, NJ, USA
| | - Gregory R Samanez-Larkin
- Department of Psychology, Yale University School of Arts and SciencesNew Haven, CT, USA; Interdepartmental Neuroscience Program, Yale UniversityNew Haven, CT, USA
| | - Chiang-Shan R Li
- Department of Psychiatry, Yale University School of MedicineNew Haven, CT, USA; Interdepartmental Neuroscience Program, Yale UniversityNew Haven, CT, USA; Department of Neurobiology, Yale University School of MedicineNew Haven, CT, USA
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Diazepam effects on aversive memory retrieval and extinction: Role of anxiety levels. Pharmacol Biochem Behav 2016; 141:42-9. [DOI: 10.1016/j.pbb.2015.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/24/2015] [Accepted: 11/27/2015] [Indexed: 11/22/2022]
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Ilieva IP, Hook CJ, Farah MJ. Prescription Stimulants' Effects on Healthy Inhibitory Control, Working Memory, and Episodic Memory: A Meta-analysis. J Cogn Neurosci 2015; 27:1069-89. [PMID: 25591060 DOI: 10.1162/jocn_a_00776] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The use of prescription stimulants to enhance healthy cognition has significant social, ethical, and public health implications. The large number of enhancement users across various ages and occupations emphasizes the importance of examining these drugs' efficacy in a nonclinical sample. The present meta-analysis was conducted to estimate the magnitude of the effects of methylphenidate and amphetamine on cognitive functions central to academic and occupational functioning, including inhibitory control, working memory, short-term episodic memory, and delayed episodic memory. In addition, we examined the evidence for publication bias. Forty-eight studies (total of 1,409 participants) were included in the analyses. We found evidence for small but significant stimulant enhancement effects on inhibitory control and short-term episodic memory. Small effects on working memory reached significance, based on one of our two analytical approaches. Effects on delayed episodic memory were medium in size. However, because the effects on long-term and working memory were qualified by evidence for publication bias, we conclude that the effect of amphetamine and methylphenidate on the examined facets of healthy cognition is probably modest overall. In some situations, a small advantage may be valuable, although it is also possible that healthy users resort to stimulants to enhance their energy and motivation more than their cognition.
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Cognitive effects of methylphenidate in healthy volunteers: a review of single dose studies. Int J Neuropsychopharmacol 2014; 17:961-77. [PMID: 24423151 DOI: 10.1017/s1461145713001594] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Methylphenidate (MPH), a stimulant drug with dopamine and noradrenaline reuptake inhibition properties, is mainly prescribed in attention deficit hyperactivity disorder, is increasingly used by the general population, intending to enhance their cognitive function. In this literature review, we aim to answer whether this is effective. We present a novel way to determine the extent to which MPH enhances cognitive performance in a certain domain. Namely, we quantify this by a percentage that reflects the number of studies showing performance enhancing effects of MPH. To evaluate whether the dose-response relationship follows an inverted-U-shaped curve, MPH effects on cognition are also quantified for low, medium and high doses, respectively. The studies reviewed here show that single doses of MPH improve cognitive performance in the healthy population in the domains of working memory (65% of included studies) and speed of processing (48%), and to a lesser extent may also improve verbal learning and memory (31%), attention and vigilance (29%) and reasoning and problem solving (18%), but does not have an effect on visual learning and memory. MPH effects are dose-dependent and the dose-response relationship differs between cognitive domains. MPH use is associated with side effects and other adverse consequences, such as potential abuse. Future studies should focus on MPH specifically to adequately asses its benefits in relation to the risks specific to this drug.
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Fosi T, Lax-Pericall MT, Scott RC, Neville BG, Aylett SE. Methylphenidate treatment of attention deficit hyperactivity disorder in young people with learning disability and difficult-to-treat epilepsy: evidence of clinical benefit. Epilepsia 2013; 54:2071-81. [PMID: 24304474 PMCID: PMC4209117 DOI: 10.1111/epi.12399] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2013] [Indexed: 11/29/2022]
Abstract
PURPOSE To establish the efficacy and safety of methylphenidate (MPH) treatment for attention deficit hyperactivity disorder (ADHD) in a group of children and young people with learning disability and severe epilepsy. METHODS This retrospective study systematically reviewed the case notes of all patients treated with methylphenidate (MPH) for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) ADHD at a specialist epilepsy center between 1998 and 2005. Treatment efficacy was ascertained using clinical global impressions (CGI) scores, and safety was indexed by instances of >25% increase in monthly seizure count within 3 months of starting MPH. KEY FINDINGS Eighteen (18) patients were identified with refractory epilepsies (14 generalized, 4 focal), IQ <70, and ADHD. Male patients predominated (13:5) and ADHD was diagnosed at a median age of 11.5 years (range 6–18 years). With use of a combination of a behavioral management program and MPH 0.3–1 mg/kg/day, ADHD symptoms improved in 61% of patients (11/18; type A intraclass correlation coefficient of CGI 0.85, 95% confidence interval [CI] 0.69–0.94). Daily MPH dose, epilepsy variables, and psychiatric comorbidity did not relate to treatment response across the sample. MPH adverse effects led to treatment cessation in three patients (dysphoria in two, anxiety in one). There was no statistical evidence for a deterioration of seizure control in this group with the use of MPH. SIGNIFICANCE Methylphenidate with behavioral management was associated with benefit in the management of ADHD in more than half of a group of children with severe epilepsy and additional cognitive impairments. Eighteen percent had significant side effects but no attributable increase in seizures. Methylphenidate is useful in this group and is likely to be under employed.
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Affiliation(s)
- Tangunu Fosi
- The National Centre for Young People with Epilepsy (NCYPE)Surrey, United Kingdom
- Great Ormond Street Hospital for Children NHS TrustLondon, United Kingdom
- Neurosciences Unit, UCL Institute of Child HealthLondon, United Kingdom
| | - Maria T Lax-Pericall
- The National Centre for Young People with Epilepsy (NCYPE)Surrey, United Kingdom
- South London and Maudsley NHS Mental Health TrustLondon, United Kingdom
| | - Rod C Scott
- The National Centre for Young People with Epilepsy (NCYPE)Surrey, United Kingdom
- Great Ormond Street Hospital for Children NHS TrustLondon, United Kingdom
- Neurosciences Unit, UCL Institute of Child HealthLondon, United Kingdom
| | - Brian G Neville
- The National Centre for Young People with Epilepsy (NCYPE)Surrey, United Kingdom
- Great Ormond Street Hospital for Children NHS TrustLondon, United Kingdom
- Neurosciences Unit, UCL Institute of Child HealthLondon, United Kingdom
| | - Sarah E Aylett
- The National Centre for Young People with Epilepsy (NCYPE)Surrey, United Kingdom
- Great Ormond Street Hospital for Children NHS TrustLondon, United Kingdom
- Neurosciences Unit, UCL Institute of Child HealthLondon, United Kingdom
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Human genome-guided identification of memory-modulating drugs. Proc Natl Acad Sci U S A 2013; 110:E4369-74. [PMID: 24145423 DOI: 10.1073/pnas.1314478110] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In the last decade there has been an exponential increase in knowledge about the genetic basis of complex human traits, including neuropsychiatric disorders. It is not clear, however, to what extent this knowledge can be used as a starting point for drug identification, one of the central hopes of the human genome project. The aim of the present study was to identify memory-modulating compounds through the use of human genetic information. We performed a multinational collaborative study, which included assessment of aversive memory--a trait central to posttraumatic stress disorder--and a gene-set analysis in healthy individuals. We identified 20 potential drug target genes in two genomewide-corrected gene sets: the neuroactive ligand-receptor interaction and the long-term depression gene set. In a subsequent double-blind, placebo-controlled study in healthy volunteers, we aimed at providing a proof of concept for the genome-guided identification of memory modulating compounds. Pharmacological intervention at the neuroactive ligand-receptor interaction gene set led to significant reduction of aversive memory. The findings demonstrate that genome information, along with appropriate data mining methodology, can be used as a starting point for the identification of memory-modulating compounds.
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Advokat C, Scheithauer M. Attention-deficit hyperactivity disorder (ADHD) stimulant medications as cognitive enhancers. Front Neurosci 2013; 7:82. [PMID: 23754970 PMCID: PMC3666055 DOI: 10.3389/fnins.2013.00082] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 05/07/2013] [Indexed: 11/13/2022] Open
Abstract
Recent increases in attention deficit hyperactivity disorder (ADHD) diagnoses, and the escalation of stimulant prescriptions, has raised concern about diversion and abuse of stimulants, as well as the ethics of using these drugs as “cognitive enhancers.”Such concern appears misplaced in the face of substantial evidence that stimulant drugs do not improve the academic performance of ADHD-diagnosed students. Moreover, numerous studies have found little or no benefit of stimulants on neuropsychological tests of ADHD-diagnosed as well as normal, individuals. This paper examines the apparent paradox: why don't drugs that improve “attention,” produce better academic outcomes in ADHD-diagnosed students? We found that stimulant drugs significantly improved impairment of episodic memory in ADHD-diagnosed undergraduate students. Nevertheless, we also found consistent academic deficits between ADHD students and their non-ADHD counterparts, regardless of whether or not they used stimulant medications. We reviewed the current literature on the behavioral effects of stimulants, to try to find an explanation for these conflicting phenomena. Across a variety of behavioral tasks, stimulants have been shown to reduce emotional reactions to frustration, improve the ability to detect errors, and increase effortful behavior. However, all of these effects would presumably enhance academic performance. On the other hand, the drugs were also found to promote “risky behavior” and to increase susceptibility to environmental distraction. Such negative effects, including the use of drugs to promote wakefulness for last minute study, might explain the lack of academic benefit in the “real world,” despite their cognitive potential. Like many drugs, stimulants influence behavior in multiple ways, depending on the environmental contingencies. Depending on the circumstances, stimulants may, or may not, enhance cognition.
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Affiliation(s)
- Claire Advokat
- Department of Psychology, Louisiana State University Baton Rouge, LA, USA
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Pre-encoding administration of amphetamine or THC preferentially modulates emotional memory in humans. Psychopharmacology (Berl) 2013; 226:515-29. [PMID: 23224510 PMCID: PMC3595317 DOI: 10.1007/s00213-012-2924-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 11/07/2012] [Indexed: 01/31/2023]
Abstract
RATIONALE Many addictive drugs are known to have effects on learning and memory, and these effects could motivate future drug use. Specifically, addictive drugs may affect memory of emotional events and experiences in ways that are attractive to some users. However, few studies have investigated the effects of addictive drugs on emotional memory in humans. OBJECTIVES This study examined the effects of the memory-enhancing drug dextroamphetamine (AMP) and the memory-impairing drug Δ(9)-tetrahydrocannabinol (THC) on emotional memory in healthy volunteers. METHODS Participants completed three experimental sessions across which they received capsules containing placebo and two doses of either AMP (10 and 20 mg; N = 25) or THC (7.5 and 15 mg; N = 25) before viewing pictures of positive (pleasant), neutral, and negative (unpleasant) scenes. Memory for the pictures was assessed 2 days later, under drug-free conditions. RESULTS Relative to placebo, memory for emotional pictures was improved by AMP and impaired by THC, but neither drug significantly affected memory for unemotional pictures. Positive memory biases were not observed with either drug, and there was no indication that the drugs' memory effects were directly related to their subjective or physiological effects alone. CONCLUSIONS This study provides the first clear evidence that stimulant drugs can preferentially strengthen, and cannabinoids can preferentially impair, memory for emotional events in humans. Although addictive drugs do not appear to positively bias memory, the possibility remains that these drugs' effects on emotional memory could influence drug use among certain individuals.
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Maul J, Advokat C. Stimulant medications for attention-deficit/hyperactivity disorder (ADHD) improve memory of emotional stimuli in ADHD-diagnosed college students. Pharmacol Biochem Behav 2013; 105:58-62. [DOI: 10.1016/j.pbb.2013.01.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 01/18/2013] [Accepted: 01/25/2013] [Indexed: 10/27/2022]
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Vrecko S. Just How Cognitive Is "Cognitive Enhancement"? On the Significance of Emotions in University Students' Experiences with Study Drugs. AJOB Neurosci 2013; 4:4-12. [PMID: 23486311 PMCID: PMC3590646 DOI: 10.1080/21507740.2012.740141] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Numerous deliberations on the ethics of cognitive enhancement take as their primary case the nonmedical use of prescription stimulant drugs by university students seeking to improve their performance in relation to academic work. Almost without exception, such discussions suggest that these medications enable academic performance enhancement through effects on cognitive processes. This article reports findings from qualitative research with nonmedical users that indicate that stimulants' effects on users' emotions and feelings are an important contributor to users' perceptions of improved academic performance. On the basis of these findings, the article suggests the conceptualization of nonmedical use of stimulants in terms of "cognitive enhancement" may fail to adequately capture the perspectives and experiences of individuals who use stimulant drugs as study aids.
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Lakhan SE, Kirchgessner A. Prescription stimulants in individuals with and without attention deficit hyperactivity disorder: misuse, cognitive impact, and adverse effects. Brain Behav 2012; 2:661-77. [PMID: 23139911 PMCID: PMC3489818 DOI: 10.1002/brb3.78] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 05/30/2012] [Accepted: 06/15/2012] [Indexed: 11/10/2022] Open
Abstract
Prescription stimulants are often used to treat attention deficit hyperactivity disorder (ADHD). Drugs like methylphenidate (Ritalin, Concerta), dextroamphetamine (Dexedrine), and dextroamphetamine-amphetamine (Adderall) help people with ADHD feel more focused. However, misuse of stimulants by ADHD and nonaffected individuals has dramatically increased over recent years based on students' misconceptions or simple lack of knowledge of associated risks. In this review, we discuss recent advances in the use and increasing misuse of prescription stimulants among high school and college students and athletes. Given the widespread belief that stimulants enhance performance, there are in fact only a few studies reporting the cognitive enhancing effects of stimulants in ADHD and nonaffected individuals. Student athletes should be apprised of the very serious consequences that can emerge when stimulants are used to improve sports performance. Moreover, misuse of stimulants is associated with dangers including psychosis, myocardial infarction, cardiomyopathy, and even sudden death. As ADHD medications are prescribed for long-term treatment, there is a need for long-term safety studies and education on the health risks associated with misuse is imperative.
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Affiliation(s)
- Shaheen E Lakhan
- Global Neuroscience Initiative Foundation Los Angeles, California
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Cognitive and emotional behavioural changes associated with methylphenidate treatment: a review of preclinical studies. Int J Neuropsychopharmacol 2012; 15:41-53. [PMID: 21439107 DOI: 10.1017/s1461145711000472] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
There is evidence from animal studies that repeated exposure to methylphenidate (MPH), a widely used psychostimulant for the treatment of attention deficit hyperactivity disorder (ADHD), produces behavioural, structural and neurochemical changes that persist long after drug administration has ended. However, the translational utility of much of this work is compromised by the use of drug doses and routes of administration that produce plasma and brain MPH levels that fall outside the clinical range, i.e. experimental parameters more relevant to drug abuse than ADHD. We used PubMed to identify pre-clinical studies that employed repeated MPH administration at low doses in young rodents and examined long-term effects on cognition, emotion, and brain structure and function. A review of this work suggests that repeated MPH treatment during early development can modify a number of cognitive, behavioural and brain processes, but these are reduced when low therapeutic doses are employed. Moreover, MPH sites of action extend beyond those implicated in ADHD. Studies that combined neurobiological and behavioural approaches provide important insights into the mechanisms underlying MPH-produced effects on cognitive and behavioural processes, which may be relevant to MPH therapeutic efficacy. There is an emerging consensus that pharmacological treatment of childhood psychiatric disorders produces persistent neuroadaptations, highlighting the need for studies that assess long-term effects of early developmental pharmacotherapy. In this regard, studies that mimic clinical therapy with rodents are useful experimental approaches for defining the behavioural and neural plasticity associated with stimulant therapy in paediatric populations.
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Smith ME, Farah MJ. Are prescription stimulants "smart pills"? The epidemiology and cognitive neuroscience of prescription stimulant use by normal healthy individuals. Psychol Bull 2012; 137:717-41. [PMID: 21859174 DOI: 10.1037/a0023825] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Use of prescription stimulants by normal healthy individuals to enhance cognition is said to be on the rise. Who is using these medications for cognitive enhancement, and how prevalent is this practice? Do prescription stimulants in fact enhance cognition for normal healthy people? We review the epidemiological and cognitive neuroscience literatures in search of answers to these questions. Epidemiological issues addressed include the prevalence of nonmedical stimulant use, user demographics, methods by which users obtain prescription stimulants, and motivations for use. Cognitive neuroscience issues addressed include the effects of prescription stimulants on learning and executive function, as well as the task and individual variables associated with these effects. Little is known about the prevalence of prescription stimulant use for cognitive enhancement outside of student populations. Among college students, estimates of use vary widely but, taken together, suggest that the practice is commonplace. The cognitive effects of stimulants on normal healthy people cannot yet be characterized definitively, despite the volume of research that has been carried out on these issues. Published evidence suggests that declarative memory can be improved by stimulants, with some evidence consistent with enhanced consolidation of memories. Effects on the executive functions of working memory and cognitive control are less reliable but have been found for at least some individuals on some tasks. In closing, we enumerate the many outstanding questions that remain to be addressed by future research and also identify obstacles facing this research.
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Affiliation(s)
- M Elizabeth Smith
- Department of Psychology, University of Pennsylvania, 3720 Walnut Street, Philadelphia, PA 19104, USA
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Advokat C. What are the cognitive effects of stimulant medications? Emphasis on adults with attention-deficit/hyperactivity disorder (ADHD). Neurosci Biobehav Rev 2010; 34:1256-66. [PMID: 20381522 DOI: 10.1016/j.neubiorev.2010.03.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Accepted: 03/28/2010] [Indexed: 11/19/2022]
Abstract
The relevant literature concerning cognitive effects of amphetamine and methylphenidate, was reviewed, with an emphasis on research conducted in adults diagnosed with attention-deficit/hyperactivity disorder. As first-line treatment for ADHD, stimulant drugs are well-known to improve attention and concentration. Yet, there is increasing evidence that (as with children and adolescents), they do not promote learning and academic achievement in adult college students with ADHD. A review of neuropsychological studies indicates that, although response latencies are reduced, performance of ADHD adults on tests of 'distractibility' and 'planning' is also not consistently improved by stimulants. Studies in non-ADHD adults suggest that stimulants do not promote acquisition of new information, might improve retention of previously acquired information, and facilitate memory consolidation, but may actually impair performance of tasks that require adaptation, flexibility and planning. It is still not clear if improvement only occurs when there is a baseline deficit. Stimulants may influence cognition by their effects on physiological arousal. Regardless, the evidence does not support the conclusion that stimulants are cognitive 'enhancers.'
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Affiliation(s)
- Claire Advokat
- Department of Psychology, Louisiana State University, 215 Audubon Hall, Baton Rouge, LA 70803, USA.
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Abstract
Emotional memories play an important role in our day-to-day experience, informing many of our minute-to-minute decisions (eg, where to go for dinner, what are the likely consequences of not attending a meeting), as well as our long-term goal setting. Individuals with schizophrenia appear to be impaired in memory for emotional experiences, particularly over longer delay periods, which may contribute to deficits in goal-related behavior and symptoms of amotivation and anhedonia. This article reviews factors that are known to influence emotional memory in healthy subjects, applies these factors to results from emotional memory studies with individuals with schizophrenia, and then uses extant neurobiological models of emotional memory formation to develop hypotheses about biological processes that might particularly contribute to emotional memory impairment in schizophrenia.
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Affiliation(s)
- Ellen S. Herbener
- Departments of Psychiatry and Psychology, University of Illinois at Chicago, IL,To whom correspondence should be addressed; Department of Psychiatry, University of Illinois at Chicago, 912 S Wood Street (M/C 913), Chicago, IL 60612, tel: 312-413-4612, fax: 312-413-7856, e-mail:
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