Why Is Working Memory Performance Unstable? A Review of 21 Factors

Screen Time Exposure and Domain-Specific Working Memory in Young Adults

Introduction With technology advancing across all fields, the utility of digital screens is increasing among all age groups for various purposes. Research indicates that while digital technology presents clear advantages, prolonged exposure can have detrimental effects on various aspects of health, behavior, emotions, and cognitive functions like attention and working memory. A crucial cognitive process for learning and information processing which is working memory, can be affected by factors including screen time. Studies have found that the impact of screen time on working memory can be negative, positive, or show no discernible relationship. However, earlier investigations are limited to smartphone use as screen time exposure and further to only active screen time. As there is a dearth of studies in the Indian context and young adults are more exposed to screen time, it is important to investigate along these lines. Hence, the present study aimed to investigate the impact of active and passive screen time exposure on modality-specific working memory in young adults. Methods Seventy-seven neurotypical individuals aged between 18 and 22 years were recruited. The study utilized auditory and visual reverse digit span tasks and the Corsi-backward task to measure working memory span. Screen time data of the participants were collected through a self-administered 18-item questionnaire covering active and background screen time domains. Results and discussion The present study concluded that only active screen time has a significant effect on visual reverse digit span and supports the notion of the visual superiority effect against an auditory superior effect as suggested by earlier findings. The preliminary findings of correlation observed exclusively within the visual domain in this study could be attributed to the potential impact of screen time exposure (active screen time and textual content). Screen usage demands effective switching between various visual stimuli and ongoing updates of information in memory. Nonetheless, interpreting this explanation and generalization requires caution, given the low ecological validity of the task employed in the study. Future investigations should aim to collect screen time exposure data more objectively, perhaps through online tracking techniques. Furthermore, it would be prudent to expand the correlation analysis to include other cognitive processes and populations.

Aerobic exercise improves verbal working memory sub-processes in adolescents: behavioral evidence from an N-back task

Background

Studies on the effects of aerobic exercise on working memory (WM) have mainly concentrated on the overall effects, yet there is little knowledge on how moderate intensity aerobic exercise impacts the sub-processes of verbal WM (VWM) in adolescents. To address this gap, two experiments were conducted to explore the influence of aerobic exercise on the maintenance and updating sub-processes of VWM.

Methods

In Experiment 1, a mixed experimental design of 2 (exercise habit: high vs. low) × 3 (memory load: 0-back vs. 1-back vs. 2-back) was used to compare VWM and its sub-processes in 40 adolescents. In Experiment 2, a 2 (group: intervention vs. control) × 3 (time point: pretest vs. 1st post-test vs. 18th post-test) × 3 (memory load: 0-back vs. 1-back vs. 2-back) mixed experimental design was used to investigate the acute and long-term effects of moderate intensity aerobic exercise on VWM and its sub-processes in 24 adolescents with low exercise habits.

Results

The results of Experiment 1 showed that VWM performance and its sub-processes in the high exercise habit group were better than those in the low exercise habit group. The results of Experiment 2 showed that the effects of the long-term exercise intervention were superior to those of the acute exercise intervention, and both were superior to the pretest. Meanwhile, it was found that aerobic exercise intervention had a greater effect size on the updating sub-process of VWM.

Conclusion

In conclusion, the results indicated that moderate intensity aerobic exercise could enhance the performance of VWM and its sub-processes in adolescents, and long-term intervention showed greater improvement effects compared to acute intervention, especially in the updating sub-process of VWM.

Exploring the dynamic interplay between learning and working memory within various cognitive contexts

Introduction

The intertwined relationship between reinforcement learning and working memory in the brain is a complex subject, widely studied across various domains in neuroscience. Research efforts have focused on identifying the specific brain areas responsible for these functions, understanding their contributions in accomplishing the related tasks, and exploring their adaptability under conditions such as cognitive impairment or aging.

Methods

Numerous models have been introduced to formulate either these two subsystems of reinforcement learning and working memory separately or their combination and relationship in executing cognitive tasks. This study adopts the RLWM model as a computational framework to analyze the behavioral parameters of subjects with varying cognitive abilities due to age or cognitive status. A related RLWM task is employed to assess a group of subjects across different age groups and cognitive abilities, as measured by the Montreal Cognitive Assessment tool (MoCA).

Results

Analysis reveals a decline in overall performance accuracy and speed with differing age groups (young vs. middle-aged). Significant differences are observed in model parameters such as learning rate, WM decay, and decision noise. Furthermore, among the middle-aged group, distinctions emerge between subjects categorized as normal vs. MCI based on MoCA scores, notably in speed, performance accuracy, and decision noise.

Stress, working memory, and academic performance: a neuroscience perspective

The relationship between stress and working memory (WM) is crucial in determining students' academic performance, but the interaction between these factors is not yet fully understood. WM is a key cognitive function that is important for learning academic skills, such as reading, comprehension, problem-solving, and math. Stress may negatively affect cognition, including WM, via various mechanisms; these include the deleterious effect of glucocorticoids and catecholamines on the structure and function of brain regions that are key for WM, such as the prefrontal cortex and hippocampus. This review explores the mechanisms underlying how stress impacts WM and how it can decrease academic performance. It highlights the importance of implementing effective stress-management strategies to protect WM function and improve academic performance.

State-level working memory and dysregulated eating in children and adolescents: An exploratory ecological momentary assessment study

BACKGROUND

Children with loss of control (LOC) eating and overweight/obesity have relative deficiencies in trait-level working memory (WM), which may limit adaptive responding to intra- and extra-personal cues related to eating. Understanding of how WM performance relates to eating behavior in real-time is currently limited.

METHODS

We studied 32 youth (ages 10-17 years) with LOC eating and overweight/obesity (LOC-OW; n = 9), overweight/obesity only (OW; n = 16), and non-overweight status (NW; n = 7). Youth completed spatial and numerical WM tasks requiring varying degrees of cognitive effort and reported on their eating behavior daily for 14 days via smartphone-based ecological momentary assessment. Linear mixed effects models estimated group-level differences in WM performance, as well as associations between contemporaneously completed measures of WM and dysregulated eating.

RESULTS

LOC-OW were less accurate on numerical WM tasks compared to OW and NW (ps < .01); groups did not differ on spatial task accuracy (p = .41). Adjusting for between-subject effects (reflecting differences between individuals in their mean WM performance and its association with eating behavior), within-subject effects (reflecting variations in moment-to-moment associations) revealed that more accurate responding on the less demanding numerical WM task, compared to one's own average, was associated with greater overeating severity across the full sample (p = .013). There were no associations between WM performance and LOC eating severity (ps > .05).

CONCLUSIONS

Youth with LOC eating and overweight/obesity demonstrated difficulties mentally retaining and manipulating numerical information in daily life, replicating prior laboratory-based research. Overeating may be related to improved WM, regardless of LOC status, but temporality and causality should be further explored.

PUBLIC SIGNIFICANCE STATEMENT

Our findings suggest that youth with loss of control eating and overweight/obesity may experience difficulties mentally retaining and manipulating numerical information in daily life relative to their peers with overweight/obesity and normal-weight status, which may contribute to the maintenance of dysregulated eating and/or elevated body weight. However, it is unclear whether these individual differences are related to eating behavior on a moment-to-moment basis.

The effects of caffeine and d-amphetamine on spatial span task in healthy participants

Studies that examined the effect of amphetamine or caffeine on spatial working memory (SWM) and verbal working memory (VWM) have used various tasks. However, there are no studies that have used spatial span tasks (SSTs) to assess the SWM effect of amphetamine and caffeine, although some studies have used digit span tasks (DST) to assess VWM. Previous reports also showed that increasing dopamine increases psychosis-like experiences (PLE, or schizotypy) scores which are in turn negatively associated with WM performance in people with high schizotypy and people with schizophrenia. Therefore, the present study aimed to examine the influence of d-amphetamine (0.45 mg/kg, PO), a dopamine releasing stimulant, on SST, DST, and on PLE in healthy volunteers. In a separate study, we examined the effect of caffeine, a nonspecific adenosine receptor antagonist with stimulant properties, on similar tasks.

METHODS

Healthy participants (N = 40) took part in two randomized, double-blind, counter-balanced placebo-controlled cross-over pilot studies: The first group (N = 20) with d-amphetamine (0.45 mg/kg, PO) and the second group (N = 20) with caffeine (200 mg, PO). Spatial span and digit span were examined under four delay conditions (0, 2, 4, 8 s). PLE were assessed using several scales measuring various aspects of psychosis and schizotypy.

RESULTS

We failed to find an effect of d-amphetamine or caffeine on SWM or VWM, relative to placebo. However, d-amphetamine increased a composite score of psychosis-like experiences (p = 0.0005), specifically: Scores on Brief Psychiatric Rating Scale, Perceptual Aberrations Scale, and Magical Ideation Scale were increased following d-amphetamine. The degree of change in PLE following d-amphetamine negatively and significantly correlated with changes in SWM, mainly at the longest delay condition of 8 s (r = -0.58, p = 0.006).

CONCLUSION

The present results showed that moderate-high dose of d-amphetamine and moderate dose of caffeine do not directly affect performances on DST or SST. However, the results indicate that d-amphetamine indirectly influences SWM, through its effect on psychosis-like experiences.

TRIAL REGISTRATION

CLINICAL TRIAL REGISTRATION NUMBER

CT-2018-CTN-02561 (Therapeutic Goods Administration Clinical Trial Registry) and ACTRN12618001292268 (The Australian New Zealand Clinical Trials Registry) for caffeine study, and ACTRN12608000610336 for d-amphetamine study.

Everyday Cognitive Control and Emotion Dysregulation in Young Adults With and Without ADHD: An Ecological Momentary Assessment Study

OBJECTIVE

This study examined the contribution of the temporal dynamics of two cognitive control mechanisms-inhibitory control (IC) and working memory (WM)-to emotion dysregulation (ED) in attention-deficit/hyperactivity disorder (ADHD) in ecological settings.

METHOD

One hundred twenty-two participants (age 18-33 years; 60 with ADHD) reported their ED at baseline, followed by a 5-day ecological momentary assessment (EMA) study, with short behavioral IC and WM tasks performed five times/day.

RESULTS

For IC, mean and lability of performance over EMA significantly accounted for differences in ED but not baseline performance. For WM, both baseline and mean of EMA, but not EMA lability, accounted for ED variance. ADHD status further contributed to the explained variance of ED.

CONCLUSIONS

Our results support the contribution of dynamic IC processes to ED in ADHD, in addition to WM performance level, and highlight the importance of dynamic and ecological investigation of different cognitive control components.

Mediterranean diet, physical activity, and family characteristics associated with cognitive performance in Italian primary school children: analysis of the I-MOVE project

Working memory (WM) is a multicomponent system that supports cognitive functioning. It has been linked to a wide variety of outcomes including academic success and general well-being. The present study examined the relations between adherence to the Mediterranean diet (MD) and WM among Italian children, adjusting for important parent characteristics and children's lifestyle habits. Data for this study was obtained from 106 children attending primary school in Imola (Italy) who were part of the I-MOVE study emphasizing school-based physical activity. Children's adherence to the MD was calculated using the KIDMED index (KI) based on the ZOOM-8 questionnaire. Physical activity (PA) levels were assessed using an actigraph accelerometer and WM using the backward digit span test. Univariate regression was used to select significant child-level and family measures associated with WM, which were then tested in a single multivariate regression model. Older age is positively associated with higher WM (β = 0.36; 95% CI 0.25, 0.47). Dietary adherence (KI) (β = 0.07; 95% CI 0.01, 0.14) and engagement in organized PA outside school hours (β = 0.58; 95% CI 0.09, 1.10) are positively related to WM. Among the family measures, father's education was positively associated with WM for high school education and for university vs. middle school or lower, respectively.

CONCLUSION

Adherence to the MD was associated with better WM capacity in primary school children. These findings can be used to guide policymakers in designing health promotion programs and instituting policies emphasizing healthy nutrition to improve physical health and boost cognitive functioning.

WHAT IS KNOWN

• The development of working memory involves the entire childhood with a rapid spurt between 2 and 8 years of age. • Working memory plays a critical role in children's learning and academic performance and underlies higher-order cognitive abilities.

WHAT IS NEW

• Adherence to the Mediterranean Diet was associated with higher working memory capacity in primary school children. • Health promotion interventions based on PA and sound nutrition involving children benefit not only physical and mental health, but also cognitive health.

Systematic reviews of the acute effects of amphetamine on working memory and other cognitive performances in healthy individuals, with a focus on the potential influence of personality traits

OBJECTIVES

This research aimed to systematically review the acute effects of amphetamine (AMP), a dopamine-releasing agent, on working memory (WM) and other cognitive performances. The investigation also aimed to review the impact of personality traits on the subjective and objective effects of AMP and possible links between personality traits and effects of AMP.

METHODS

Previous double-blind controlled studies assessing the main effects of AMP on WM and other cognitive performances in healthy volunteers were systematically reviewed. An electronic search was performed in the PUBMED and SCOPUS databases. Narrative reviews of the influence of personality traits on the subjective and objective effects of AMP were included.

RESULTS

Nineteen WM studies were included in the current review. Seven studies found effects of AMP on spatial WM, but only one study found the effect of AMP on verbal WM. Thirty-seven independent studies on other aspects of cognitive performance were identified. Twenty-two reported effects of AMP on cognitive functions. Studies also showed that personality traits are associated with the subjective effects of AMP. However, few studies reported the impacts of personality traits on the objective (such as WM) effects of AMP.

CONCLUSION

Overall, findings indicate that AMP has mixed-effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM. Although there are insufficient studies on objective measures, studies also indicated that the subjective effects of AMP administration are linked to between-person variations in personality traits.

Trajectories of Cognitive Impairment in Adults Bearing Vascular Risk Factors, with or without Diagnosis of Mild Cognitive Impairment: Findings from a Longitudinal Study Assessing Executive Functions, Memory, and Social Cognition

With the aging of the population, a key concern of both societies and health services is to keep the population cognitively healthy until the maximum age limit. It is a well-known fact that vascular aging has a negative effect on the cognitive skills of adults, putting them at greater risk of developing dementia. The present longitudinal study aimed to evaluate the main dimensions of cognition in two pathological groups with different health profiles: a group of adults with vascular risk factors (VRF) (n = 35) and a group of adults with vascular risk factors and mild cognitive impairment (VRF + MCI) (n = 35). The two groups were matched in age, education, and gender. They were assessed with extensive neuropsychological testing at three different times with a distance of about 8 months between them; the assessment regarded executive functions, memory capacity, and Theory of Mind abilities. The analyses carried out were (a) mixed-measures ANOVA, (b) repeated measures ANOVA, and (c) ANOVA. The findings showed that global cognitive status and short-term memory are the main cognitive abilities that decline in community dwelling people bearing VRF. Hence, this group of adults should be examined at least every 2 years for this decline. As regards people with both VRF and MCI, it seems that the assessment of Theory of Mind abilities can better capture their further impairment. Global cognitive status, task/rule switching function, and long-term memory (delayed verbal recall) were revealed as the abilities that clearly and steadily differentiate VRF people with and without MCI.

Does IQ Influence Association Between Working Memory and ADHD Symptoms in Young Adults?

OBJECTIVE

This study examined the association between WM and ADHD symptoms in young adults and whether IQ-score influenced this association.

METHOD

Data from the 1993 Pelotas (Brazil) Birth Cohort Study were analyzed (N = 2,845). Working memory and ADHD symptoms were collected at 22 years. IQ was examined at age 18. Poisson regression with robust variance was used to assess the associations between working memory and ADHD symptoms. We also evaluated whether IQ modified associations between working memory and ADHD symptoms.

RESULTS

Working memory was negatively associated with Inattention symptoms of ADHD. The association between working memory and hyperactivity-impulsivity symptoms of ADHD varied by IQ.

CONCLUSIONS

This study provides new insights to theories about the relationship between WM and ADHD symptoms as well as the development of interventions aimed at improving the performance of WM in ADHD.

Working Memory Phenotypes in Early Multiple Sclerosis: Appraisal of Phenotype Frequency, Progression and Test Sensitivity

Working memory (WM) impairments are common and debilitating symptoms of multiple sclerosis (MS), often emerging early in the disease. Predominantly, WM impairments are considered in a binary manner, with patients considered either impaired or not based on a single test. However, WM is comprised of different activated subcomponents depending upon the type of information (auditory, visual) and integration requirements. As such, unique WM impairment phenotypes occur. We aimed to determine the most frequent WM phenotypes in early MS, how they progress and which WM test(s) provide the best measure of WM impairment. A total of 88 participants (63 early relapsing–remitting MS: RRMS, 25 healthy controls) completed five WM tests (visual–spatial, auditory, episodic, executive) as well as the symbol digit modalities test as a measure of processing speed. RRMS patients were followed-up for two years. Factors affecting WM (age/gender/intelligence/mood) and MS factors (disease duration/disability) were also evaluated. Some 61.9% of RRMS patients were impaired on at least one WM subcomponent. The most subcomponents impaired were visual,–spatial and auditory WM. The most common WM phenotypes were; (1) visual–spatial sketchpad + episodic buffer + phonological loop + central executive, (2) visual–spatial sketchpad + central executive. The test of visual–spatial WM provided the best diagnostic accuracy for detecting WM impairment and progression. The SDMT did not achieve diagnostic accuracy greater than chance. Although this may be unsurprising, given that the SDMT is a measure of cognitive processing speed in MS, this does highlight the limitation of the SDMT as a general screening tool for cognitive impairment in early MS.

Electronic Cigarette Vaping Did Not Enhance the Neural Process of Working Memory for Regular Cigarette Smokers

Background

Electronic cigarettes (e-cigs) as substitute devices for regular tobacco cigarettes (r-cigs) have been increasing in recent times. We investigated neuronal substrates of vaping e-cigs and smoking r-cigs from r-cig smokers.

Methods

Twenty-two r-cig smokers made two visits following overnight smoking cessation. Functional magnetic resonance imaging (fMRI) data were acquired while participants watched smoking images. Participants were then allowed to smoke either an e-cig or r-cig until satiated and fMRI data were acquired. Their craving levels and performance on the Montreal Imaging Stress Task and a 3-back alphabet/digit recognition task were obtained and analyzed using two-way repeated-measures analysis of variance. Regions-of-interest (ROIs) were identified by comparing the abstained and satiated conditions. Neuronal activation within ROIs was regressed on the craving and behavioral data separately.

Results

Craving was more substantially reduced by smoking r-cigs than by vaping e-cigs. The response time (RT) for the 3-back task was significantly shorter following smoking r-cigs than following vaping e-cigs (interaction: F (1, 17) = 5.3, p = 0.035). Neuronal activations of the right vermis (r = 0.43, p = 0.037, CI = [-0.05, 0.74]), right caudate (r = 0.51, p = 0.015, CI = [0.05, 0.79]), and right superior frontal gyrus (r = −0.70, p = 0.001, CI = [−0.88, −0.34]) were significantly correlated with the RT for the 3-back task only for smoking r-cigs.

Conclusion

Our findings suggest that insufficient satiety from vaping e-cigs for r-cigs smokers may be insignificant effect on working memory function.

Comparing the Effects of Two Cardiovascular Health Factors on Working Memory Capacity in Healthy Aging: Separate and Combined Effects of Arterial Elasticity and Physical Fitness

OBJECTIVES

Arterial elasticity and physical fitness are 2 important cardiovascular health factors that influence cognition in older adults. Working memory capacity (WMC), a core component underlying cognitive aging across many cognitive domains, may be affected by individual differences in cardiovascular health in older adults. This study aims to identify in older adults: (a) separate and combined effects of these 2 cardiovascular health factors on WMC and (b) which of the 2 factors is more critical in influencing WMC.

METHODS

WMC in 89 healthy older adults was assessed by 2 complex span tasks. Arterial elasticity was assessed by pulse pressure (PsP). Physical fitness was measured by an established proxy of VO2 max (MET). Effects of PsP and MET on WMC were evaluated via step-wise regressions.

RESULTS

After controlling for age, sex, and education, PsP and MET were separately predictive of WMC in older adults. Together, the combined effect of PsP and MET was more predictive of WMC than fitness alone, but not more than PsP alone. Mediation analysis indicates that the relationship between MET and WMC was completely mediated by PsP.

DISCUSSION

This study innovatively demonstrates that though arterial elasticity and physical fitness separately predict WMC, the former completely mediates the relationship between fitness and WMC. This suggests that biologically based cardiovascular health factors like arterial elasticity are crucial individual difference variables that should be measured and monitored in cognitive aging studies as well as in physical interventions that are designed to improve cognition in healthy aging.

Can dog-assisted and relaxation interventions boost spatial ability in children with and without special educational needs? A longitudinal, randomized controlled trial

Children's spatial cognition abilities are a vital part of their learning and cognitive development, and important for their problem-solving capabilities, the development of mathematical skills and progress in Science, Technology, Engineering and Maths (STEM) topics. As many children have difficulties with STEM topic areas, and as these topics have suffered a decline in uptake in students, it is worthwhile to find out how learning and performance can be enhanced at an early age. The current study is the first to investigate if dog-assisted and relaxation interventions can improve spatial abilities in school children. It makes a novel contribution to empirical research by measuring longitudinally if an Animal-Assisted Intervention (AAI) or relaxation intervention can boost children's development of spatial abilities. Randomized controlled trials were employed over time including dog intervention, relaxation intervention and no treatment control groups. Interventions were carried out over 4 weeks, twice a week for 20 min. Children were tested in mainstream schools (N = 105) and in special educational needs (SEN) schools (N = 64) before and after interventions, after 6 weeks, 6 months and 1 year. To assess intervention type and to provide advice for subsequent best practice recommendations, dog-assisted interventions were run as individual or small group interventions. Overall, children's spatial abilities improved over the year with highest increases in the first 4 months. In Study 1, typically developing children showed higher scores and more continuous learning overall compared to children with special educational needs. Children in the dog intervention group showed higher spatial ability scores immediately after interventions and after a further 6 weeks (short-term). Children in the relaxation group also showed improved scores short-term after relaxation intervention. In contrast, the no treatment control group did not improve significantly. No long-term effects were observed. Interestingly, no gender differences could be observed in mainstream school children's spatial skills. In study 2, children in SEN schools saw immediate improvements in spatial abilities after relaxation intervention sessions. No changes were seen after dog interventions or in the no treatment control group. Participants' pet ownership status did not have an effect in either cohort. These are the first findings showing that AAI and relaxation interventions benefit children's spatial abilities in varied educational settings. This research represents an original contribution to Developmental Psychology and to the field of Human-Animal Interaction (HAI) and is an important step towards further in-depth investigation of how AAI and relaxation interventions can help children achieve their learning potential, both in mainstream schools and in schools for SEN.

Screen time and working memory in adolescents: A longitudinal study

Little is known about the effects of excessive screen time on Working Memory (WM) in adolescents. The aim of this study was to investigate the association between measures of screen time in adolescence and Working Memory. Data from the 1993 Pelotas (Brazil) Birth Cohort Study were analyzed (N = 3625). Self-reported screen time was collected at ages 11, 15 and 18. Working Memory performance (Digit Span backward score) was examined at age 22. Multiple linear regression was used to assess the associations between three screen time measures (television, video game and computer time) for each age and WM at age 22. We also evaluated the direct and indirect effect by mediation analysis, using the intelligence quotient (IQ) at 18 years as mediator. In men, television and video game time at 11 years and computer at ages 11 and 15 years had a positive effect on WM. Also, these effects were mediated through IQ. In women there was no significant association between screen time measures at ages 11, 15, and 18 and WM. This study provides new insights about the relationship between television, videogame, and computer time with WM in adolescents, by exploring the paths of these associations and considering the important mediating role of IQ.

Spatial working memory in young adolescents with different childhood trajectories of internalizing, conduct and hyperactivity/inattention problems

BACKGROUND

In children, internalizing and externalizing problems impact on learning. However, there is limited research on the specific impact of such problems on spatial working memory (SWM), strongly related to cognitive ability and children's learning.

AIMS

We explored distinct trajectories of internalizing problems and externalizing problems (conduct problems and hyperactivity/inattention) in a large general-population sample of children followed from age 3 to age 11 years. We then assessed their role in SWM performance at age 11 years.

SAMPLE

Data were drawn from the UK's Millennium Cohort Study. Our analytic sample was children with data on SWM at age 11 years (N = 12,589).

METHODS

There were two stages of data analysis. Trajectory group membership was firstly estimated by group-based trajectory modelling for internalizing problems, conduct problems, and hyperactivity/inattention at ages 3-11 years. Multiple regression then assessed the relationship between SWM at age 11 years and trajectory group membership after accounting for confounders.

RESULTS

Trajectories of internalizing, conduct, and hyperactivity/inattention symptoms across ages 3 to 11 years were related to SWM at age 11 years, even after controlling for confounding variables. For each of the three symptom domains, poor SWM was most consistently found in children with chronically high levels of symptoms.

CONCLUSIONS

In general, atypical patterns of internalizing problems, conduct problems, and hyperactivity/inattention in childhood were related to poorer SWM in early adolescence.

Controlled sleep deprivation as an experimental medicine model of schizophrenia: An update

In recent years there has been a surge of interest and corresponding accumulation of knowledge about the role of sleep disturbance in schizophrenia. In this review, we provide an update on the current status of experimentally controlled sleep deprivation (SD) as an experimental medicine model of psychosis, and also consider, given the complexity and heterogeneity of schizophrenia, whether this (state) model can be usefully combined with other state or trait model systems to more powerfully model the pathophysiology of psychosis. We present evidence of dose-dependent aberrations that qualitatively resemble positive, negative and cognitive symptoms of schizophrenia as well as deficits in a range of translational biomarkers for schizophrenia, including prepulse inhibition, smooth pursuit and antisaccades, following experimentally controlled SD, relative to standard sleep, in healthy volunteers. Studies examining the combination of SD and schizotypy, a trait model of schizophrenia, revealed only occasional, task-dependent superiority of the combination model, relative to either of the two models alone. Overall, we argue that experimentally controlled SD is a valuable experimental medicine model of schizophrenia to advance our understanding of the pathophysiology of the clinical disorder and discovery of more effective or novel treatments. Future studies are needed to test its utility in combination with other, especially state, model systems of psychosis such as ketamine.

Older Adults Who Meditate Regularly Perform Better on Neuropsychological Functioning and Visual Working Memory Tests: A Three-month Waitlist Control Design Study with a Cohort of Seniors in Assisted Living Facilities

Background: Neuropsychological functioning and visual working memory are vulnerable to age-related decline. This investigation examines the impact of meditation on the said outcomes for older adults in assisted living facilities. Older adults (N = 136) from four assisted living facilities in Mumbai and Pretoria were randomized into intervention and waitlist control groups.Method: The Repeatable Battery for Assessment of Neuropsychological Status (RBANS) was used as a screening instrument for recruitment (cutoff total index score = 86 ± 4). RBANS, the Simple Object Span Test (SOST), and the Picture Span Test (PST) were used to assess the outcomes. The intervention group underwent a 90-day meditation training complemented with self-practice.Results: Posttest scores of the intervention group were higher. Older adult men, with college degree, middle class, widowed, in fair health, with no diagnosed psychiatric conditions, who attended at least 70 (out of 90) meditation lessons and who self-practiced at least 70 times, gained more from the meditation intervention. Intervention compliance had the strongest effect on posttest outcomes as well as sex and psychiatric morbidities.Conclusion: Meditation intervention needs some refinements for older adult women, with high school education, upper class, currently married, in poor health, with diagnosed anxiety/depression/drug dependence, who attended fewer meditation lessons and self-practiced infrequently.

Effect of ageing on verbal and visuo-spatial working memory: Evidence from 880 individuals

It is well-known that ageing is associated with a decrease in working memory abilities. It is not so clear at what age the decline begins and if there are differences in the decline of verbal and visuo-spatial working memory. This study investigates the effect of ageing on verbal and visuo-spatial working memory by comparing the performance of 880 subjects aged between 15- and 80-year old who were subdivided into five groups. The results show that age is negatively correlated with performance on both verbal and visuo-spatial working memory tasks. Specifically, we observed a gradual deterioration in performance with increasing age starting at 36-year old. Comparing the performance of the five groups, it is possible to observe a clear decline in both verbal and visuo-spatial working memory domains in subjects over 66-year old. However, in the next youngest age group, it is possible to notice differences in performance depending on the type of material being processed and the cognitive load required. This variability is discussed by analyzing the factors that may have influenced test performance.

Changes in Working Memory Performance Over an Academic Semester in Student Pharmacists

Objective. To preliminarily assess changes in Doctor of Pharmacy students' working memory performance over the course of an academic semester and to determine whether any observed changes were associated with fluctuations in stress and fatigue. Methods. Twenty-three PharmD students were recruited for this pilot study. At baseline, data were collected on students' personality, stress, fatigue, and working memory performance using two measures, the operation span and the symmetry span. Approximately every four weeks throughout the semester students' fatigue and stress levels were reassessed and they completed the two measures of working memory. A repeated measures analysis of variance was used to assess trends over time, and correlation analysis was used to assess potential relationships between working memory and other variables. Results. The operation span, a measure of general working memory resources, showed a significant quadratic trend over time. Irrespective of time, some associations between working memory performance and fatigue were seen. Significant correlations between fatigue and the extraversion personality trait were identified. The symmetry span, a measure of visuospatial resources, did not show trends over time nor did it correlate with fatigue, stress, or personality factors. Conclusion. Pharmacy students' working memory performance may fluctuate over the course of a semester, but more research is needed to identify factors that may influence this fluctuation.

Physical Activity versus Psychological Stress: Effects on Salivary Cortisol and Working Memory Performance

Background and Objective: The present study was designed to investigate whether acute physical activity and psychological stress produce different effects on cortisol release and working memory performance. Materials and Methods: Male subjects (N = 12; 18–35 years) were recruited and scheduled to come four times to our lab (within-subject design). For each counterbalanced visit, they performed one of the following four protocols: control, moderate physical activity (MOD), vigorous physical activity (VIG), and acute stress. Heart rate was monitored during every protocol. MOD and VIG were performed for 15 min and were defined as 40–50% and 70–80%, respectively, of their maximum heart rate. Acute stress was imposed via the Trier Social Stress Test (TSST). Salivary samples were collected before and after every protocol to assess cortisol concentrations. Working memory (WM) performance was evaluated through the 2N-Back task right after ending the protocol (early WM) and after a delay of 35 min (late WM). Results: VIG and stress, but not MOD, increased salivary cortisol concentrations. However, the increases of cortisol produced by VIG and stress were not significantly different. Also, there were no significant differences in working memory performance (late and early) in any of the experimental protocols tested. Conclusions: These results show that exercise (VIG) and stress produce similar effects on cortisol release and do not support the hypothesis that working memory capacity is influenced by elevated cortisol levels, either from varying exercise intensities or psychological stress.

Decreased Information Replacement of Working Memory After Sleep Deprivation: Evidence From an Event-Related Potential Study

Working memory (WM) components are altered after total sleep deprivation (TSD), both with respect to information replacement and result judgment. However, the electrophysiological mechanisms of WM alterations following sleep restriction remain largely unknown. To identify such mechanisms, event-related potentials were recorded during the n-back WM task, before and after 36 h sleep deprivation. Thirty-one young volunteers participated in this study and performed a two-back WM task with simultaneous electroencephalography (EEG) recording before and after TSD and after 8 h time in bed for recovery (TIBR). Repeated measures analysis of variance revealed that, compared to resting wakefulness, sleep deprivation induced a decrease in the P200 amplitude and induced longer reaction times. ERP-component scalp topographies results indicated that such decrease primarily occurred in the frontal cortex. The N200 and P300 amplitudes also decreased after TSD. Our results suggest that decreased information replacement of WM occurs after 36 h of TSD and that 8 h TIBR after a long period of TSD leads to partial restoration of WM functions. The present findings represent the EEG profile of WM during mental fatigue.

Does mindfulness training help working memory 'work' better?

There has been a proliferation of mindfulness training (MT) programs offered across a multitude of settings, including military, business, sports, education, and medicine. As such, ascertaining training effectiveness and determining best practices for program delivery are of the utmost importance. MT is often introduced to promote an array of desired effects from better mood, better leadership and management skills, to improved workplace or academic performance. Despite the diversity of factors motivating adoption of MTs, it can be argued from a cognitive training perspective that there should be uniformity in the core cognitive processes strengthened via repeated and systematic engagement in MT exercises. Herein, we explore the hypothesis that MT promotes salutary changes in the brain's working memory (WM) system. We review prior research and highlight aspects of MT programs that may be critical for achieving beneficial WM effects. Further, we suggest that given the centrality of WM in core processes such as emotion regulation, problem solving, and learning, MT programs capable of achieving WM benefits may be best positioned to promote other desired outcomes (e.g. reductions in negative mood). For these reasons, we recommend that more studies include WM metrics in their evaluation of MT programs.