Effects of methylphenidate on memory functions of adults with ADHD

Assessment of goal-directed behavior and prospective memory in adult ADHD with an online 3D videogame simulating everyday tasks

The diagnosis of ADHD is based on real-life attentional-executive deficits, but they are harder to detect in adults than in children and objective quantitative measures reflecting these everyday problems are lacking. We developed an online version of EPELI 3D videogame for naturalistic and scalable assessment of goal-directed action and prospective memory in adult ADHD. In EPELI, participants perform instructed everyday chores in a virtual apartment from memory. Our pre-registered hypothesis predicted weaker EPELI performances in adult ADHD compared to controls. The sample comprised 112 adults with ADHD and 255 neurotypical controls comparable in age (mean 31, SD = 8 years), gender distribution (71% females) and educational level. Using web-browser, the participants performed EPELI and other cognitive tasks, including Conner's Continuous Performance Test (CPT). They also filled out questionnaires probing everyday executive performance and kept a 5-day diary of everyday prospective memory errors. Self-reported strategy use in the EPELI game was also examined. The ADHD participants' self-ratings indicated clearly more everyday executive problems than in the controls. Differences in the EPELI game were mostly seen in the ADHD participants' higher rates of task-irrelevant actions. Gender differences and a group × gender interaction was found in the number of correctly performed tasks, indicating poorer performance particularly in ADHD males. Discriminant validity of EPELI was similar to CPT. Strategy use strongly predicted EPELI performance in both groups. The results demonstrate the feasibility of EPELI for online assessment and highlight the role of impulsivity as a distinctive everyday life problem in adult ADHD.

Cognitive Performance and Psychiatric Self-Reports Across Adult Cognitive Disengagement Syndrome and ADHD Diagnostic Groups

OBJECTIVE

Cognitive disengagement syndrome (CDS) is characterized by inattention, under-arousal, and fatigue and frequently co-occurs with attention-deficit/hyperactivity disorder (ADHD). Although CDS is associated with cognitive complaints, its association with objective cognitive performance is less well understood.

METHOD

This study investigated neuropsychological correlates of CDS symptoms among 169 adults (M_age = 29.4) referred for outpatient neuropsychological evaluation following inattention complaints. We evaluated cognitive and self-report differences across four high/low CDS and positive/negative ADHD groups, and cognitive and self-report correlates of CDS symptomology.

RESULTS

There were no differences in cognitive performance, significant differences in self-reported psychiatric symptoms (greater CDS symptomatology, impulsivity among the high CDS groups; greater inattention among the positive ADHD/high CDS groups; greater hyperactivity among the positive ADHD groups), significant intercorrelations within cognitive and self-report measures, nonsignificant correlations between cognitive measures and self-report measures.

CONCLUSION

Findings support prior work demonstrating weak to null associations between ADHD and CDS symptoms and cognitive performance among adults.

Networks of Neuropsychological Functions in the Clinical Evaluation of Adult ADHD

This study applied network analysis to explore the relations between neuropsychological functions of individuals in the clinical evaluation of attention-deficit/hyperactivity disorder (ADHD) in adulthood. A total of 319 participants from an outpatient referral context, that is, 173 individuals with ADHD (ADHD group) and 146 individuals without ADHD (n-ADHD group), took part in this study and completed a comprehensive neuropsychological assessment. A denser network with stronger global connectivity was observed in the ADHD group compared to the n-ADHD group. The strongest connections were consistent in both networks, that is, the connections between selective attention and vigilance, and connections between processing speed, fluency, and flexibility. Further centrality estimation revealed attention-related variables to have the highest expected influence in both networks. The observed relationships between neuropsychological functions, and the high centrality of attention, may help identify neuropsychological profiles that are specific to ADHD and optimize neuropsychological assessment and treatment planning of individuals with cognitive impairment.

The effects of psychostimulants on cognitive functions in individuals with attention-deficit hyperactivity disorder: A systematic review

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with a broad range of deficits in cognitive functions which has significant implications for quality of life. Psychostimulants are demonstrated to improve symptoms of inattention and hyperactivity/impulsivity, however, their impact on cognition remains incompletely characterized. Herein, the aim of this systematic review is to synthesize the extant literature reporting on the effects of psychostimulants on cognitive function in individuals with ADHD.

METHOD

A systematic search of PubMed, Scopus, and Web of Science from inception to July 2021 was conducted. Additional studies were identified through Google Scholar and a manual search of the reference lists of relevant articles. Inclusion criteria were original studies that evaluated the cognitive function of individuals with ADHD taking psychostimulants drugs. We assessed the quality of the included papers using the Newcastle-Ottawa scale (NOS).

RESULTS

A total of 10 studies involving 753 subjects with ADHD and 194 healthy controls were identified and eligible for inclusion. Nine studies evaluated the impact of methylphenidate on cognitive function and one study investigated the use of lisdexamfetamine. Results indicated that attentional deficits such as memory, vigilance, divided attention, phasic and tonic alertness, and focused attention were improved in ADHD patients treated with psychostimulants. The efficacy of psychostimulants in improving other domains of cognition remains inconclusive due to conflicting evidence or insignificant findings (ie. academic performance and executive function). Overall, results indicate that psychostimulants may improve only select domains of cognition (ie. memory and attention).

CONCLUSION

Psychostimulants are reported to improve several disparate aspects of cognition among individuals with ADHD. Further research is needed to better understand the complex relationships between cognition and behavior in ADHD, as well as the impact of medication on these distinct aspects of functioning. Further research is also needed to determine whether the pro-cognitive effect of stimulants would be transferable to other mental disorders.

The impact of childhood deprivation on adult neuropsychological functioning is associated with ADHD symptom persistence

BACKGROUND

Institutional deprivation in early childhood is associated with neuropsychological deficits in adolescence. Using 20-year follow-up data from a unique natural experiment - the large-scale adoption of children exposed to extreme deprivation in Romanian institutions in the 1980s -we examined, for the first time, whether such deficits are still present in adulthood and whether they are associated with deprivation-related symptoms of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).

METHODS

Adult neuropsychological functioning was assessed across five domains (inhibitory control, emotion recognition, decision-making, prospective memory and IQ) in 70 previously institutionalized adoptees (mean age = 25.3, 50% female) and 22 non-deprived UK adoptees (comparison group, mean age = 24.6, 41% female). ADHD and ASD symptoms were assessed using parent-completed questionnaires.

RESULTS

Early institutionalization was associated with impaired performance on all tasks in adulthood. Prospective memory deficits persisted after controlling for IQ. ADHD and ASD symptoms were positively correlated. After controlling for ASD symptoms, ADHD symptoms remained associated with deficits in IQ, prospective memory, proactive inhibition, decision-making quality and emotion recognition. ASD symptoms were not independently associated with neuropsychological deficits when accounting for their overlap with ADHD symptoms. Multiple regression analysis revealed that the link between childhood deprivation and adult ADHD symptoms was statistically explained by deprivation-related differences in adult IQ and prospective memory.

CONCLUSIONS

These results represent some of the most compelling evidence to date of the enduring power of early, time-limited childhood adversity to impair long-term neuropsychological functioning across the lifespan - effects that are linked specifically to deprivation-related adult ADHD symptoms.

Neuropsychological functioning of individuals at clinical evaluation of adult ADHD

OBJECTIVES

Numerous studies showed that adults with attention deficit hyperactivity disorder (ADHD) suffer from impairments in a range of cognitive functions when compared to healthy controls. However, only little is known about the neuropsychological functions when compared to various clinical control groups and whether a distinct neuropsychological profile can be identified for adult ADHD.

METHOD

This retrospective study examined data of 199 outpatients referred for clinical evaluation of adult ADHD, allocated either to an ADHD group (n = 78) or to one of two clinical comparison groups, depending on whether they show indications (n = 71) or no indications (n = 50) for the presence of psychiatric disorders other than ADHD. All individuals performed a comprehensive neuropsychological test battery.

RESULTS

Data analysis revealed impairments in a range of cognitive functions in a substantial number of patients of all three groups. However, profiles of neuropsychological impairments were similar between groups. Furthermore, significant small- to medium-sized correlations between basic and higher-order cognitive functions were revealed in the ADHD group and the clinical comparison group with indications for psychiatric disorders other than ADHD.

CONCLUSION

Neuropsychological impairments are prominent in psychiatric outpatients seeking a clinical evaluation of adult ADHD but are not specific for ADHD. It is concluded that neuropsychological test performance may have limited incremental value to support the psychiatric differential diagnosis. Furthermore, a clinical trajectory may need to take into account that deficits in a range of higher-order cognitive functions can be substantially explained by deficits in basic cognitive functions.

Is Attention-Deficit/Hyperactivity Disorder a Risk Syndrome for Parkinson's Disease?

Recent epidemiological evidence indicates that diagnosis of attention-deficit/hyperactivity disorder (ADHD) is associated with increased risk for diseases of the basal ganglia and cerebellum, including Parkinson's disease (PD). The evidence reviewed here indicates that deficits in striatal dopamine are a shared component of the causal chains that produce these disorders. Neuropsychological studies of adult ADHD, prodromal PD, and early-stage PD reveal similar deficits in executive functions, memory, attention, and inhibition that are mediated by similar neural substrates. These and other findings are consistent with the possibility that ADHD may be part of the PD prodrome. The mechanisms that may mediate the association between PD and ADHD include neurotoxic effects of stimulants, other environmental exposures, and Lewy pathology. Understanding the nature of the association between PD and ADHD may provide insight into the etiology and pathogenesis of both disorders. The possible contribution of stimulants to this association may have important clinical and public health implications.

Cognitive characterization of adult attention deficit hyperactivity disorder by domains: a systematic review

Attention deficit hyperactivity disorder (ADHD) is reportedly the most frequent neurodevelopmental disorder diagnosed during childhood, and it is recognized as a common condition in adulthood. We review the evidence to help identify cognitive domains associated to deficits in adult ADHD. A systematic review with narrative synthesis was performed, assessing studies on adult ADHD, neuropsychology and research on involved cognitive domains in adults 18+ years old with an established diagnosis of ADHD, in seven electronic databases (PubMed, PsychInfo, WebOfScience, Embase, Scopus, OvidSPMedline, and Teseo), and Worldcat and OpenGrey grey literature databases. 93 studies were included for this review, encompassing findings from a total 5574 adults diagnosed only with ADHD, medication-naïve or non-medicated at the moment of the assessment and 4880 healthy controls. Adults diagnosed with ADHD may show, when compared to healthy controls, a cognitive profile characterized by deficits across all attention modalities, processing speed, executive function (mainly working memory and inhibition with emphasis on reward delay and interference control), verbal memory, reading skills, social cognition and arithmetic abilities. A cognitive characterization of adult ADHD by domains is established beyond the sole consideration of attention and executive function problems. Along with these, verbal memory, language (mainly reading), social cognition and arithmetic abilities may also contribute to a more comprehensive characterization of the cognitive profile in adult ADHD.

The effect of medication and question wording on self-reported symptoms and their accuracy in young adults with attention-deficit/hyperactivity disorder

OBJECTIVES

This study examined the effect of whether participants were on or off their medications and the effect of questionnaire wording on self-reported symptoms in young adults with ADHD. Additionally, this research evaluated the relationships between these self-reported symptoms and objective performance on measures of working memory.

DESIGN

This experimental study utilized a mixed factorial design with one between-subjects factor (whether participants were unmedicated or medicated at the time they completed their assessment) and one within-subjects factor (whether participants reported their on-medication or off-medication symptoms when describing their ADHD subjective symptomatology).

METHODS

Forty-five young adults with ADHD (ages 18-23) completed a brief neuropsychological evaluation and several self-report questionnaires.

RESULTS

Although being medicated or unmedicated while completing the questionnaires did not directly affect self-reported symptoms or their accuracy, questionnaire wording exerted a statistically significant effect on subjective symptomatology; participants described themselves as substantially more symptomatic at times when they are off than at times when they are on their medications. More importantly, their general self-perceptions (symptoms when medication state was not specified) of their Inattention/Memory Problems and their Hyperactivity/Restlessness aligned with their descriptions of their off-medication symptoms, whereas their general self-perceptions of their Impulsivity/Emotional Lability and Problems with Self-Concept related to both their self-reported off-medication and on-medication symptoms.

CONCLUSIONS

These results highlight the necessity of specifying medication state when asking patients to report their current symptomatology. Failing to do so risks an over-reporting of symptoms from patients who are typically on medications as they may describe the extent of their unmedicated, rather than medicated, symptomatology.

PRACTITIONER POINTS

Being medicated or unmedicated while completing questionnaires about subjective symptomatology did not directly affect self-reported symptoms of young adults with ADHD or the accuracy of these self-reports. When medication state was not specified on a questionnaire, young adults with ADHD reported symptoms similar to those they experience when they are not medicated. These results highlight the importance of specifying medication state when asking young adults with ADHD to report their current symptomatology. Failing to do so risks an over-reporting of symptoms from patients who are typically on medications. These findings open the door for further research with larger and more diverse and representative samples of adults with ADHD to evaluate the accuracy of their subjective symptomatology relative to their objective abilities. Future studies should also examine whether gender affects subjective symptoms, their accuracy, or the influence of question wording and medications on self-reported symptomatology of adults with ADHD, as the current study was unable to address this important issue.

Methylphenidate for attention problems in epilepsy patients: Safety and efficacy

Children with attention deficit hyperactivity disorder (ADHD) have an increased risk of seizures, and children with epilepsy have an increased prevalence of ADHD. Adults with epilepsy often have varying degrees of attentional dysfunction due to multiple factors, including anti-seizure medications, frequent seizures, interictal discharges, underlying lesions, and psychiatric comorbidities. Currently, there are no approved medications for the treatment of epilepsy-related attentional dysfunction. Methylphenidate (MPH) is a stimulant, FDA-approved for the treatment of ADHD, and often used for ADHD in the setting of pediatric epilepsy. Large database and registry studies indicate safety of MPH in children with ADHD and epilepsy, with no significant effect on seizure frequency. Small single-dose and open-label studies suggest efficacy of MPH in adults with epilepsy-related attention deficits. Methylphenidate represents a possible treatment for attentional dysfunction due to epilepsy, but large, randomized, placebo-controlled, double-blinded studies are needed.

Adult attention-deficit/hyperactivity disorder symptoms, cognitive dysfunction and quality of life in high-dose use of benzodiazepine and Z-drug

High-dose use of benzodiazepines (BZDs) and Z-drugs was found to be associated with adult attention deficit/hyperactivity disorder (ADHD) and multidomain cognitive deficits, but the interplay between these factors and its effect on quality of life (QoL) is unclear. We explored (a) whether cognitive dysfunction differs in high-dose BZD/Z-drug users with and without adult ADHD and (b) the impact of cognitive deficits and adult ADHD on QoL in this substance-use disorder (SUD). From January 2015 to December 2019, we recruited 207 high-dose BZD/Z-drug users seeking treatment. We assessed the presence of adult ADHD with a screening tool, which was validated in SUD patients, and collected demographic, clinical and QoL data from the 76 included patients. A neuropsychological battery explored five cognitive domains. We found that: (a) screening for adult ADHD was frequently positive; (b) Short Form-36 (SF-36), a self-administered QoL questionnaire, was worse than the general population and worse in patients positive (ADHD+) vs. those negative (ADHD−) to ADHD screening tool; (c) executive function was significantly worse in ADHD+ than ADHD− patients; (d) some SF-36 dimensions were negatively influenced by executive dysfunction; (e) multivariate analysis showed an interplay between adult ADHD and cognitive dysfunction in worsening QoL. We documented a complex interplay between adult ADHD, cognitive dysfunction and QoL in high-dose BZD/Z-drug users. Assessing adult ADHD, neuropsychological measures and QoL may offer a full scenario of these patients, who are frequently impaired in everyday activities. Future research should explore whether pharmacological treatment might improve cognitive dysfunction and QoL in this SUD.

Is Methylphenidate Beneficial and Safe in Pharmacological Cognitive Enhancement?

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.

The female side of pharmacotherapy for ADHD-A systematic literature review

OBJECTIVE

This comprehensive review examined sex differences in prescription rates and efficacy or effectiveness of pharmacotherapy treatment in girls and women with attention deficit hyperactivity disorder (ADHD), while identifying gaps in the scientific knowledge on this topic.

METHOD

A rigorous electronic database search was carried out in order to identify all published studies on female-specific effects of stimulants and non-stimulants in the treatment of ADHD. In total, 2672 studies were screened of which 21 studies (seven on prescription rates, 14 on effects of pharmacotherapy) met the inclusion criteria and were included for analysis.

RESULTS

In all seven studies on ADHD prescription rates, girls received significantly less prescriptions than boys, a difference however no longer seen in adults with the exception of one study. Each of the 14 studies on effectiveness / efficacy found at least one sex-difference in the effects of ADHD pharmacotherapy.

CONCLUSION

Several sex-differences are demonstrated in the prescription, usage and efficacy /effectiveness of both stimulant and non-stimulant ADHD pharmacotherapy. A single daily use of MPH may possibly not be optimal for girls with ADHD and ATX may be a promising medication for girls and women with ADHD. The robustness of this result requires further investigation.

Methylphenidate treatment of adult ADHD patients improves the degree of ADHD severity under routine conditions

Attention-deficit hyperactivity disorder (ADHD) is associated with substantial personal and social impairments. Besides psychosocial interventions, current guidelines recommend a therapy with methylphenidate (MPH). This prospective, non-interventional study aims to investigate the efficacy and tolerability of MPH treatment of adult ADHD patients in a real-world setting. 468 adult patients with newly diagnosed ADHD were observed for 12–14 weeks. Primary efficacy endpoint was the clinical global impression (CGI) by the physician. Secondary endpoints comprise patient evaluation (Wender–Reimherr self-report, WR-SR), safety, tolerability, and dosage of MPH. With a mean daily dose of 35.8 (±17.0) mg MPH, the population of patients being severely/most extremely ill or markedly ill decreased by 64% and 61%, respectively. According to physicians’ assessment (CGI), 74.5% of patients were identified as treatment responders. The total score of patient-based assessment (WR-SR) improved by 23.5% (50.1 ± 40.3 points) with the most profound improvement in attention deficit (−30.0%), disorganization (−26.6%), and hyperactivity / unrest (−23.3%). Self-evaluation revealed a responder rate of 35.4%. In summary, MPH treatment improves the degree of ADHD severity under routine conditions. In addition, activities of daily living were facilitated when taking MPH. The rather poor responder rates determined by patient assessment as well as the comparatively low applied mean daily dose of 35.8 mg (median 40 mg) indicate sub-optimal dosing under routine conditions, not exploiting the full beneficial therapeutic potential of MPH.

A comparison of efficacy between cognitive behavioral therapy (CBT) and CBT combined with medication in adults with attention-deficit/hyperactivity disorder (ADHD)

The study aimed to explore whether cognitive behavioral therapy (CBT) combined with medication is superior to CBT alone in core symptoms, emotional symptoms, self-esteem as well as social and cognitive functions of adult attention-deficit/hyperactivity disorder (ADHD) patients. Samples from a previous RCT study and outpatient participants were all included. A total of 124 patients received 12 weeks of manualized CBT sessions, either with (n = 57) or without (n = 67) medication. Efficacy variables were evaluated at baseline and each week. Mixed linear models (MLM) were used to compare differences between the two groups in all of the above domains. Within-group comparisons showed that both groups had robust improvements in core ADHD symptoms, emotional symptoms and social functional outcomes. The CBT + M group presented more domains of improvement in executive functions than the CBT group. However, comparisons between groups didn't indicate the superiority of CBT + M in core symptoms, emotional symptoms and self-esteem. Instead, the CBT group showed a greater improvement in the physical domain of the WHOQOL-BREF than the CBT + M group. This study further indicated that CBT is an effective treatment for adults with ADHD. A combination of CBT and medication presented broader improvements in executive functions, but not in clinical symptoms, than CBT alone.

Basic processes as foundations of cognitive impairment in adult ADHD

Attention deficit hyperactivity disorder (ADHD) in adulthood is associated with impairment of multiple aspects of cognition which adversely affect the individual's everyday functioning. However, little is known about how these impairments are intertwined. This study explores whether impairments in basic processes (processing speed and distractibility) in adults with ADHD explain impairments in higher order functions, namely executive functions, memory, and complex attention. Furthermore, it is explored whether pharmacological treatment with methylphenidate (MPH) affects basic processes and higher order functions. A between-subjects design compared patients with ADHD without stimulant drug treatment (N = 55) and patients with ADHD treated with MPH (N = 31) with a healthy control group (N = 80). A neuropsychological test battery assessing basic processes and higher order functions was administered. Hierarchical logistic regression analyses were performed to evaluate the contribution of basic processes to impairments in higher order functions. Patients with ADHD not treated with MPH showed impairments in basic processes and higher order functions compared to controls. The impairments in basic processes explained 41-43% of impairments in executive functions, 27-29% in memory, and 56-74% in complex attention. In patients with ADHD treated with MPH, basic processes were not impaired and did not contribute significantly to impairments of higher order functions. Basic processes may constitute part of the foundation of cognitive impairments in adult ADHD. MPH may improve cognitive performance, presumably through improving basic processes. Applying this information could optimize neuropsychological assessments and inform treatment strategies by targeting basic processes.

Systematic review and meta-analysis of the behavioral effects of methylphenidate in the spontaneously hypertensive rat model of attention-deficit/hyperactivity disorder

The spontaneously hypertensive rats (SHR) are the most widely used model for ADHD. While face and construct validity are consolidated, questions remain about the predictive validity of the SHR model. We aim at summarizing the evidence for the predictive validity of SHR by evaluating its ability to respond to methylphenidate (MPH), the most well documented treatment for ADHD. A systematic review was carried out to identify studies evaluating MPH effects on SHR behavior. Studies (n=36) were grouped into locomotion, attention, impulsivity or memory, and a meta-analysis was performed. Meta-regression, sensitivity, heterogeneity, and publication bias analyses were also conducted. MPH increased attentional and mnemonic performances in the SHR model and decreased impulsivity in a dose-dependent manner. However, MPH did not reduce hyperactivity in low and medium doses, while increased locomotor activity in high doses. Thus, since the paradoxical effect of stimulant in reducing hyperactivity was not observed in the SHR model, our study does not fully support the predictive validity of SHR, questioning their validity as an animal model for ADHD.

Production Effect in Adults With ADHD With and Without Methylphenidate (MPH): Vocalization Improves Verbal Learning

OBJECTIVES

Reading aloud (vocal production) enhances memory relative to reading silently, the Production Effect (PE) in memory. Thus, vocalization has been suggested as a mnemonic device. The current study tested the PE in a sample of adults with ADHD and in a control sample, evaluating verbal learning.

METHODS

Twenty adults with ADHD and 21 controls learned a list of words, half by reading aloud and half by reading silently. Free recall test followed. The participants with ADHD performed the task twice (in two different sessions in a counterbalanced order), before self-administration of a single dose of methylphenidate (MPH) and 60-min after dosage.

RESULTS

PEs were found for all groups. Memory was better for the controls than for the ADHD group (with or without MPH). In the ADHD group, recall rates and the PE were higher with than without MPH.

CONCLUSIONS

These results suggest that vocalization yields a larger memory gain with MPH. Possibly, MPH enables the ADHD participants to better shift their attention to the aloud words, enhancing their retrieval rates. Theoretically, these findings stress the role of attention in the PE. (JINS, 2019, 25, 230-235).

A single dose of cocaine enhances prospective memory performance

BACKGROUND

Prospective memory is the ability to recall intended actions or events at the right time or in the right context. While cannabis is known to impair prospective memory, the acute effect of cocaine is unknown. In addition, it is not clear whether changes in prospective memory represent specific alterations in memory processing or result from more general effects on cognition that spread across multiple domains such as arousal and attention.

AIMS

The main objective of the study was, therefore, to determine whether drug-induced changes in prospective memory are memory specific or associated with more general drug-induced changes in attention and arousal.

METHODS

A placebo-controlled, three-way, cross-over study including 15 regular poly-drug users was set up to test the influence of oral cocaine (300 mg) and vaporised cannabis (300+150 'booster' µg/kg bodyweight) on an event-based prospective memory task. Attentional performance was assessed using a divided attention task and subjective arousal was assessed with the Profile of Mood States questionnaire.

RESULTS

Results showed that cocaine enhanced prospective memory, attention and arousal. Mean performance of prospective memory and attention, as well as levels of arousal were lowest during treatment with cannabis as compared with placebo and cocaine as evinced by a significantly increased trend across treatment conditions. Prospective memory performance was only weakly positively associated to measures of attention and arousal.

CONCLUSION

Together, these results indicate that cocaine enhancement of prospective memory performance cannot be fully explained by parallel changes in arousal and attention levels, and is likely to represent a direct change in the neural network underlying prospective memory.