Working Memory Reaction Time Research Articles

Acute Aerobic Exercise Intensity on Working Memory and Vigilance After Nap Deprivation: Effects of Low-Intensity Deserve Attention.

Napping deprivation in habitual nappers leads to cognitive impairment. The ameliorative effect of acute aerobic exercise has been demonstrated for this post-cognitive impairment. However, it is still unclear which intensity of aerobic exercise is the most effective and how long this improvement can be sustained. Fifty-eight healthy adults with a chronic napping habit were randomly assigned to four intervention groups after undergoing nap deprivation: a sedentary control group, a low-intensity exercise group (50-59% maximum heart rate, HRmax), a moderate-intensity exercise group (60-69% HRmax), and a high-intensity exercise group (70-79% HRmax). Working memory (N-back task), vigilance (Psychomotor Vigilance Task, PVT), and response inhibitory capacity (Go/NoGo task) were measured. Regression analyses showed a quadratic trend between exercise intensity and working memory reaction time and accuracy (F =3.297-5.769, p < 0.05, R2 =10.7-18.9%). The effects of exercise were optimal at low-intensity. There was a significant quadratic trend between exercise intensity and PVT lapse (F =4.314, p =0.042, R² =7.2%). The effect of exercise increased with higher intensity. Prolonged observation found that the effect of low-intensity exercise on working memory was maintained for 2 hours. The effect of low-intensity exercise might be underestimated. Low-intensity exercise significantly improved working memory performance, and the effects could be maintained throughout the afternoon. In contrast, the effects of high-intensity exercise were unlikely to be maintained and might even have negative effects. Future researchers can broaden the categories of participants to enhance the external validity and collect diverse physiological indicators to explore related physiological mechanisms.

Effects of aerobic exercise training on cerebral pulsatile hemodynamics in middle-aged adults with elevated blood pressure/stage 1 hypertension.

Mechanisms behind the protective effects of aerobic exercise on brain health remain elusive but may be vascular in origin and relate to cerebral pulsatility. This pilot study investigated the effects of 12-wk aerobic exercise training on cerebral pulsatility and its vascular contributors (large artery stiffness, characteristic impedance) in at-risk middle-aged adults. Twenty-eight inactive middle-aged adults with elevated blood pressure or stage 1 hypertension were assigned to either moderate/vigorous aerobic exercise training (AET) for 3 days/wk or no-exercise control (CON) group. Middle cerebral artery (MCA) pulsatility index (PI), large artery (i.e., aorta, carotid) stiffness, and characteristic impedance were assessed via Doppler and tonometry at baseline, 6, and 12 wk, whereas cardiorespiratory fitness (V̇o2peak) was assessed via incremental exercise test and cognitive function via computerized battery at baseline and 12 wk. V̇o2peak increased 6% in AET and decreased 4% in CON (P < 0.05). Proximal aortic compliance increased (P = 0.04, partial η2 = 0.14) and aortic characteristic impedance decreased (P = 0.02, partial η2 = 0.17) with AET but not CON. Cerebral pulsatility showed a medium-to-large effect size increase with AET, although not statistically significant (P = 0.07, partial η2 = 0.11) compared with CON. Working memory reaction time improved with AET but not CON (P = 0.02, partial η2 = 0.20). Our data suggest 12-wk AET elicited improvements in central vascular hemodynamics (e.g., proximal aortic compliance and characteristic impedance) along with apparent, paradoxical increases in cerebral pulsatile hemodynamics.NEW & NOTEWORTHY We identify differential central versus cerebrovascular responses to 12 wk of aerobic exercise training in middle-aged adults. Although proximal aortic compliance and characteristic impedance improved after 12 wk of exercise, cerebral pulsatility tended to unexpectedly increase. These data suggest short-term aerobic exercise training may lead to more immediate benefits in the central vasculature, whereas longer duration exercise training may be required for beneficial changes in pulsatility within the cerebrovasculature.

Cognition after a 4-week high phenylalanine intake in adults with phenylketonuria – a randomized controlled trial

BackgroundPhenylketonuria (PKU) is an autosomal recessive metabolic disorder characterized by increased phenylalanine (Phe) concentrations in the blood and brain. Despite wide agreement on treatment during childhood, recommendations for adults are still controversial. ObjectiveTo assess the impact of a 4-week increase in Phe intake (simulating normal dietary Phe consumption) on cognition, mood, and depression in early-treated adults with PKU in a double-blind, randomized controlled trial (RCT). MethodsIn a single-site crossover trial, 30 adult patients with classical PKU diagnosed at birth were recruited. All patients underwent a 4-week period of oral Phe administration (1500–3000 mg Phe/d) and a 4-week placebo period in a randomly assigned order with age, sex, and place of usual medical care as stratification factors. Analyses were based on the intention-to-treat (ITT) and per protocol (PP) approach to claim noninferiority (noninferiority margin –4%), with working memory accuracy as the primary endpoint and additional cognitive domains, mood, and depression as secondary endpoints. ResultsFor the primary endpoint, a 4-week increase of Phe intake was noninferior to placebo with respect to working memory accuracy in both the ITT [point estimate 0.49; lower limit 95% confidence interval (CI): −1.99] and the PP analysis (point estimate −1.22; lower limit 95% CI: −2.60). Secondary outcomes (working memory reaction time, manual dexterity, mood, and depression) did not significantly differ between the Phe and placebo period, except for sustained attention (point estimate 31.0; lower limit 95% CI: 9.0). Adverse events were more frequent during the Phe than during the placebo period (95% CI: 1.03, 2.28, P = 0.037). ConclusionsIn early-treated adult patients with PKU, a 4-week high Phe intake was noninferior to continuing Phe restriction regarding working memory accuracy, and secondary outcomes did not differ except for sustained attention. Longer-term RCTs are required to determine whether low Phe levels need to be maintained throughout different periods of adulthood.This trial was registered at the clinicaltrials.gov as NCT03788343.

The Effects of Transcranial Direct Current Stimulation (tDCS) on the Cognitive Functions: A Systematic Review and Meta-analysis.

Previous studies have investigated the effect of transcranial direct current stimulation (tDCS) on cognitive functions. However, these studies reported inconsistent results due to differences in experiment design, measurements, and stimulation parameters. Nonetheless, there is a lack of meta-analyses and review studies on tDCS and its impact on cognitive functions, including working memory, inhibition, flexibility, and theory of mind. We performed a systematic review and meta-analysis of tDCS studies published from the earliest available data up to October 2021, including studies reporting the effects of tDCS on cognitive functionsin human populations. Therefore, these systematic review and meta-analysis aim to comprehensively analyze the effects of anodal and cathodal tDCS on cognitive functions by investigating 69 articles with a total of 5545 participants. Our study reveals significant anodal tDCS effects on various cognitive functions. Specifically, we observed improvements in working memory reaction time (RT), inhibition RT, flexibility RT, theory of mind RT, working memory accuracy, theory of mind accuracyand flexibility accuracy. Furthermore, our findings demonstrate noteworthy cathodal tDCS effects, enhancing working memory accuracy, inhibition accuracy, flexibility RT, flexibility accuracy, theory of mind RT, and theory of mind accuracy. Notably, regarding the influence of stimulation parameters of tDCS on cognitive functions, the results indicated significant differences across various aspects, including the timing of stimulation (online vs. offline studies), population type (clinical vs. healthy studies), stimulation duration (< 15 min vs. > 15 min), electrical current intensities (1-1.5 m.A vs. > 1.5 m.A), stimulation sites (right frontal vs. left frontal studies), age groups (young vs. older studies), and different cognitive tasks in each cognitive functioning aspect. In conclusion, our results demonstrate that tDCS can effectively enhance cognitive task performance, offering valuable insights into the potential benefits of this method for cognitive improvement.

The effect of tDCS electrode montage on attention and working memory

The effects of transcranial direct current stimulation (tDCS) for improving attention and working memory have been generally mixed and small, potentially due to variability between studies with montages, stimulus parameters and outcome measures. The tDCS montage is an important parameter which determines the degree and intensity of stimulation in targeted brain regions. This study aimed to examine the effects of using three different montages for modulating attention and working memory performance: Bi-frontal, Broad-frontal and Broad-parietal. Ninety-three healthy adults participated in a counterbalanced cross-over study. Participants received both active and sham tDCS with either the Bi-frontal, Broad-frontal or Broad-parietal montage during performance of both a 1- and 2-back task. TDCS montage moderated 2-back working memory reaction time performance, though not accuracy, with faster reaction times observed for active compared to sham tDCS with the Broad-frontal montage only (F (1,90) = 5.26, p = .024, η2 = 0.06). TDCS montage did not significantly moderate performance on the 1-back task. The cognitive effects of tDCS varied according to montage, task, and outcome measure. TDCS administered with the cathode placed extracephalically in a Broad-frontal montage may be beneficial for improving working memory.

The effect of tDCS electrode montage on attention and working memory.

The effects of transcranial direct current stimulation (tDCS) for improving attention and working memory have been generally mixed and small, potentially due to variability between studies with montages, stimulus parameters and outcome measures. The tDCS montage is an important parameter which determines the degree and intensity of stimulation in targeted brain regions. This study aimed to examine the effects of using three different montages for modulating attention and working memory performance: Bi-frontal, Broad-frontal and Broad-parietal. Ninety-three healthy adults participated in a counterbalanced cross-over study. Participants received both active and sham tDCS with either the Bi-frontal, Broad-frontal or Broad-parietal montage during performance of both a 1- and 2-back task. TDCS montage moderated 2-back working memory reaction time performance, though not accuracy, with faster reaction times observed for active compared to sham tDCS with the Broad-frontal montage only (F (1,90)=5.26, p=.024, η2=0.06). TDCS montage did not significantly moderate performance on the 1-back task. The cognitive effects of tDCS varied according to montage, task, and outcome measure. TDCS administered with the cathode placed extracephalically in a Broad-frontal montage may be beneficial for improving working memory.

Working memory-related alterations in neural oscillations reveal the influence of in-vehicle toluene on cognition at low concentration.

Although toluene is a typical in-vehicle pollutant, the impacts of in-vehicle toluene exposure on cognitive functions remain unestablished. Therefore, this study aimed to investigate the effects of short-term toluene exposure in vehicles on working memory based on neural oscillations. In total, 24 healthy adults were recruited. Each subject was exposed to four different concentrations of toluene and divided into 0ppb, 17.5ppb, 35ppb, and 70ppb groups for self-control studies. After 4h of exposure to each concentration of toluene, a behavioral test of visual working memory was performed while 19-channel electroencephalogram (EEG) signals were collected. Meanwhile, the power spectral density (PSD) and spatial distribution of working memory encoding, maintenance, and extraction periods were calculated by short-time Fourier transform to clarify the characteristic frequency bands, major brain regions, and characteristic channels of each period. To compare the changes in the characteristic patterns of neural oscillations under the effect of different concentrations of toluene. There was no significant difference in working memory reaction time and correct rate between the groups at different toluene concentrations (p > 0.05). The characteristic frequency band of the working memory neural oscillations in each group was the theta frequency band; the PSD of the theta frequency band was predominantly concentrated in the frontal area, and the characteristic channel was the Fz channel. The whole brain (F = 3.817, p < 0.05; F = 4.758, p < 0.01; F = 3.694, p < 0.05), the frontal area (F = 2.505, p < 0.05; F = 2.839, p < 0.05; F = 6.068, p < 0.05), the Fz channel (F = 3.522, p < 0.05; F = 3.745, p < 0.05; F = 6.526, p < 0.05), and the PSD of working memory in the theta frequency band was significantly increased in the 70ppb group compared with the other three groups during the coding, maintenance, and retrieval phases of working memory. When the in-vehicle toluene exposure concentration was 70ppb, the PSD of the characteristic frequency bands of working memory was significantly increased in the whole brain, major brain regions, and characteristic channels.

Transcranial direct current stimulation modulates working memory and prefrontal-insula connectivity after mild-moderate traumatic brain injury.

Background: Persistent posttraumatic symptoms (PPS) may manifest after a mild-moderate traumatic brain injury (mmTBI) even when standard brain imaging appears normal. Transcranial direct current stimulation (tDCS) represents a promising treatment that may ameliorate pathophysiological processes contributing to PPS.Objective/Hypothesis: We hypothesized that in a mmTBI population, active tDCS combined with training would result in greater improvement in executive functions and post-TBI cognitive symptoms and increased resting state connectivity of the stimulated region, i.e., left dorsolateral prefrontal cortex (DLPFC) compared to control tDCS.Methods: Thirty-four subjects with mmTBI underwent baseline assessments of demographics, symptoms, and cognitive function as well as resting state functional magnetic resonance imaging (rsfMRI) in a subset of patients (n = 24). Primary outcome measures included NIH EXAMINER composite scores, and the Neurobehavioral Symptom Inventory (NSI). All participants received 10 daily sessions of 30 min of executive function training coupled with active or control tDCS (2 mA, anode F3, cathode right deltoid). Imaging and assessments were re-obtained after the final training session, and assessments were repeated after 1 month. Mixed-models linear regression and repeated measures analyses of variance were calculated for main effects and interactions.Results: Both active and control groups demonstrated improvements in executive function (EXAMINER composite: p < 0.001) and posttraumatic symptoms (NSI cognitive: p = 0.01) from baseline to 1 month. Active anodal tDCS was associated with greater improvements in working memory reaction time compared to control (p = 0.007). Reaction time improvement correlated significantly with the degree of connectivity change between the right DLPFC and the left anterior insula (p = 0.02).Conclusion: Anodal tDCS improved reaction time on an online working memory task in a mmTBI population, and decreased connectivity between executive network and salience network nodes. These findings generate important hypotheses for the mechanism of recovery from PPS after mild-moderate TBI.

The Use of Smartphone Serious Gaming Apps in the Treatment of Substance Use Disorders: Observational Study on Feasibility and Acceptability.

BackgroundAddiction is a worldwide problem with major health complications. Despite intensive treatment, relapse rates remain high. The prevalence of cognitive impairment is high in patients with substance use disorders (SUDs) and is associated with treatment dropout and relapse. Evidence indicates that cognitive function training in persons with SUDs may support treatment. Therefore, the use of web-based tools to test and train cognitive functions is of increasing interest.ObjectiveThe goal of this study was to determine the feasibility and acceptability of a serious gaming smartphone app to test and train cognitive functions in addition to the treatment of SUDs.MethodsA prospective observational study was conducted with 229 patients seeking addiction treatment. The patients were offered 2 smartphone apps in addition to regular care: MyCognition Quotient (MyCQ) assessed cognitive functions and AquaSnap trained these functions. The feasibility was determined based on acceptance rates. The acceptability of the smartphone apps was qualitatively analyzed based on the answers to a questionnaire. Patient characteristics were compared between patients who played and did not play smartphone games. Explorative correlation analyses were performed between the playing time and cognitive assessment scores.ResultsOf the 229 patients who were offered the apps, 110 completed the MyCQ assessment, and 59 started playing AquaSnap, yielding acceptance rates of 48.0% and 25.8%, respectively. The group that completed the MyCQ assessment was significantly more educated than the group that did not download the apps (χ22=7.3; P=.03). The education level did not differ significantly between the group that played AquaSnap and the group that did not (P=.06). There were relatively more women in the AquaSnap playing group than in the nonplaying group (χ21=6.5; P=.01). The groups did not differ in terms of age, substance use, treatment setting, mood, or quality of life. With respect to acceptability, 83% (38/46) of the patients who filled out the questionnaire enjoyed taking the MyCQ measurement, whereas 41% (14/34) enjoyed playing the AquaSnap game. Furthermore, 76% (35/46) and 68% (23/34) rated the apps MyCQ and AquaSnap, respectively, as easy. More playing minutes was associated with decreased working memory reaction time and executive functioning accuracy.ConclusionsOur study showed that the use of a smartphone app for cognitive assessment in patients with SUDs who are interested and highly educated is feasible and acceptable for the subgroup that was asked to fill out a perception questionnaire. However, the use of a smartphone app for cognitive training was less feasible for this group of patients. Improvement of the training application and enhancement of the motivation of clients are needed. Despite these limitations, the present results provide support for future research investigating the use of smartphone apps for cognitive assessment and training in relation to the treatment of SUDs.

Subcortical Volume Changes in Early Menopausal Women and Correlation With Neuropsychological Tests.

Background: The aging process and declining estradiol levels are two important factors that cause structural brain alterations. Many prior studies have investigated these two elements and revealed controversial results in menopausal women. Here, a cross-sectional study was designed to individually evaluate estradiol-related structural changes in the brain.Methods: A total of 45 early menopausal women and 54 age-matched premenopausal controls were enrolled and subjected to magnetic resonance imaging (MRI) scans, blood biochemistry tests, and neuropsychological tests. MRI structural images were analyzed using FreeSurfer to detect changes in subcortical and cortical volumes as well as cortical thickness. Finally, structural brain data as well as clinical and neuropsychological data were used for Pearson’s correlation analyses to individually determine estradiol-related structural and functional changes in the brains of early menopausal women.Results: Compared with the premenopausal controls, the early menopausal women showed significant subcortical volumetric loss in the left amygdala and right amygdala, higher serum follicle-stimulating hormone (FSH) levels, more recognizable climacteric and depressive symptoms, decreased quality of sleep, and decreased working memory and executive functions. Simultaneously, FSH levels were related to lower working memory accuracy and longer working memory reaction time. Decreased subcortical volume in the bilateral amygdala was also related to lower working memory accuracy and longer executive reaction time in early menopausal women.Conclusion: The data suggest that estradiol deficiency in early menopausal women can lead to subcortical volume and functional brain changes, which may contribute to further understanding the neurobiological role of declined estradiol levels in early menopausal women.

Examining Working Memory Performance in Adult Psychosomatic Inpatients.

BackgroundThere is cumulating evidence that working memory (WM) processing is impaired in individuals suffering from a psychosomatic and a psychological disorder. However, it is unclear how repetitive negative thinking (RNT), depressive symptoms, and patient characteristics (i.e., age and incapability to work) contribute to WM impairments. The present study examines how these factors affect WM performance in highly distressed adult psychosomatic inpatients.MethodsSeventy-six inpatients (Mage = 52.7, SD = 8.4) from a psychosomatic rehabilitation clinic performed a two-block WM updating task, with accuracy and reaction time as indicators of WM functioning.ResultsMultivariate mixed effect model results show that accuracy and reaction time significantly decreased from WM Block 1 to WM Block 2. Higher levels of RNT, more severe depressive symptoms and higher age were associated with worse WM accuracy in Block 1. None of these variables were significantly associated with WM reaction time (in Block 1).ConclusionFrom a clinical perspective, the results suggest that screening for the presence of high RNT levels, severe depressive symptoms or higher age may help to identify patients with impaired WM functioning and to intervene on these important patient characteristics early in the rehabilitation process.

Cognitive Dysfunction in Insomnia Phenotypes: Further Evidence for Different Disorders.

Study Objectives: To determine cognitive profiles in individuals with short sleep duration insomnia (SSDI) and normal sleep duration insomnia (NSDI; also, paradoxical insomnia), compared to healthy sleepers.Method: Polysomnographic (PSG) and neuropsychological data were analysed from 902 community-based Raine Study participants aged 22 ± 0.6 years of whom 124 met criteria for insomnia (53 with NSDI and 71 with or SSDI) and 246 were classified as healthy with normal sleep (i.e., without insomnia or other sleep disorders). Measurements of self- report (attention and memory) and laboratory-assessed (attention, episodic memory, working memory, learning, and psychomotor function) cognition and mood, and PSG-based sleep stages (% total sleep time; %TST) were compared between these 3 groups.Results: In comparison to the healthy sleeper group, both insomnia groups had poorer self-reported attention, memory, mood, and sleep, and poorer laboratory-assessed attention (inconsistency). The NSDI group had less consistent working memory reaction time than healthy-sleepers or those with SSDI. The SSDI group had more inconsistency in executive function (shifting), and showed greater %TST in stage N1 and N3, and less REM sleep than either healthy-sleepers or those with NSDI.Conclusions: Individuals with NSDI demonstrated greater working memory inconsistency, despite no laboratory assessed sleep problems, implicating early signs of pathophysiology other than disturbed sleep. Those with SSDI demonstrated different sleep architecture, poorer attention (inconsistency), and greater executive function (inconsistency) compared to healthy-sleepers and those with NSDI, implicating sleep disturbance in the disease process of this phenotype.

The Effects of Low-Intensity Multimodal Proprioceptive Exercise on Cognitive Function in Older Adults.

Physical activity provides a number of physical and psychological benefits. Multimodal proprioceptive exercise represents a useful balance-based exercise with the potential to reduce falls in older adults. Previous research has also indicated cognitive benefits following multimodal proprioceptive exercise in young and older adults. This study aimed to assess cognition and mood following 2 types of physical activity (multimodal proprioception vs yoga) compared with control (classroom-based) in healthy older adults. Nineteen older adults (Mage = 65, sex = 9 males) participated in this randomized controlled crossover trial. Participants completed a 20-minute multimodal proprioceptive exercise class, 20-minute yoga session, and 20-minute classroom-based control. Numeric working memory and mood were assessed before and immediately following each of the interventions. The multimodal proprioceptive intervention significantly reduced numeric working memory reaction time versus the yoga (P = .043) and control (P = .023) group. There were no differences found for accuracy or mood. These results indicate that multimodal proprioceptive exercise is worthy of further investigation as an alternative mode of exercise alongside the more traditional aerobic and strength-based exercise for healthy older adults.

318 - Does one size fit all? Evaluating individual temporal associations between affect and cognitive function in older adults using a single-subject design

IntroductionDepression and cognitive impairments often co-occur in older adults and account for a high disease burden. Insight into how affect and cognitive function influence one another on a daily basis could be helpful in the diagnostic process and treatment decisions for individual patients. However, little is known about the daily associations between affect and cognitive function in older adults and it is unknown whether these associations differ per person. Therefore, the objective of this study was to get insight into the temporal associations between affect and cognitive function within individual older adults.Materials &amp; MethodsFor this single-subject study eight older adults with depression and cognitive impairments filled in electronic diaries for 63 consecutive days in their home environment. The diaries included a questionnaire evaluating positive affect (PA), negative affect (NA) and a computerized cognitive test battery assessing working memory reaction time (WMRT) and visual learning accuracy (VLA). Time-series analyses using Vector Autoregressive (VAR) modelling were conducted for each individual separately. Granger causality tests were used to determine the temporal direction of the individual associations. Cumulative Orthogonalized Impulse Response Function (COIRF) analyses were performed in order to determine the cumulative effect size over a 10-day period. The contemporaneous associations were derived from the correlation between the residuals in the VAR model.ResultsFor one out of eight participants higher NA was associated with better WMRT the next day (cumulative effect size=0.345; p=0.005). For another participant higher NA and lower PA were associated with worse WMRT at the same time (r=-0.369; p=0.003 and r=0.352; p=0.005, respectively). For a third participant better VLA was associated with lower NA (cumulative effect size=-0.569; p&lt;0.001) and higher PA the next day (cumulative effect size=0.223; p=0.001). The other five participants showed no contemporaneous or lagged association between affect and cognitive function.ConclusionFor the majority of individuals we found no contemporaneous or temporal association between affect and cognitive functioning. For the others, the associations differed in direction, sign and size. This highlights heterogeneity even in a small and relatively homogeneous sample. Future studies should evaluate how individual data can be used in personalizing diagnoses and treatments.

Contributions of Cognitive Aging Models to the Explanation of Source Memory Decline across the Adult Lifespan

ABSTRACTBackground: A number of cognitive aging models have been proposed to explain the age-related decline in several cognitive functions, but these models have rarely been examined together. We analyzed the contributions of four main models – processing resources, speed of processing, cognitive reserve and knowledge – to source memory decay related to the aging process.Methods: A total of 1554 healthy adults between 21 and 80 years old participated in the study. Structural equation modeling was conducted on data from the whole sample and separately in the data from young, middle-aged and older adult age groups. To estimate each cognitive model, we measured working memory discrimination levels (processing resources), working memory reaction times (speed of processing), education (cognitive reserve) and vocabulary (knowledge).Results: Processing resources mediate the effects of age on source memory across the adult lifespan, whereas speed of processing mediates these effects only in young adults, cognitive reserve only in middle-aged adults and knowledge only in older adults.Conclusions: Processing resources was the cognitive model that most contributes to explaining source memory decay. The fact that the other models are relevant to specific age groups provides useful information to exploit their benefits to preserve source memory in specific life stages.

25-hydroxyvitamin D Levels are Associated with Cognitive Dysfunction in Type 2 Diabetes and the Metabolic Syndrome: A Preliminary Examination

Background: Type 2 diabetes (T2DM) and metabolic syndrome are linked to pathological changes in the brain and increased likelihood of cognitive impairment. Vitamin D insufficiency is commonly found in this population and is associated with cognitive dysfunction in other patient groups. The present study aims to demonstrate the presence of cognitive deficit in individuals with T2DM and metabolic syndrome, and determine if level of vitamin D is associated with cognitive deficit in this population. Methods: Twenty individuals with T2DM and metabolic syndrome (n = 20, aged 45 to 72) were recruited for this cross-sectional study from a subspecialty diabetes center. All completed computerized cognitive testing and clinical evaluation, including assessment of circulating vitamin D values. Pearson correlations determined the association between vitamin D value and test performance. Results: Cognitive dysfunction was prevalent, particularly in domains of executive function (e.g., Verbal Interference-Color Word, 47%) and attention (e.g., Working Memory Reaction Time, 50%; Digit Span, 30%). Lower vitamin D values were associated with poorer executive function test performance (Switching of Attention-Letters/Numbers, r = 0.64; Maze Errors, r = 0.47). Conclusions: Cognitive dysfunction was prevalent, and lower vitamin D values were associated with poorer executive function test performance. It is unclear if vitamin D directly affects cognition in this population, or if it serves as a proxy for another mechanism affecting cognition, such as poorer glycemic control or sedentary lifestyle. Prospective studies involving vitamin D supplementation may be of benefit in addressing the possible causal role of vitamin D in cognition for this population.

Adolescent cannabis use and brain systems supporting adult working memory encoding, maintenance, and retrieval

Given prior reports of adverse effects of cannabis use on working memory, an executive function with a protracted developmental course during adolescence, we examined associations between developmental patterns of cannabis use and adult working memory (WM) processes. Seventy-five adults with longitudinal assessments of cannabis use (60 with reported use, 15 with no reported use) and prenatal drug exposure assessment completed a spatial WM task during fMRI at age 28. All subjects passed a multi-drug urine screen on the day of testing and denied recreational drug use in the past week. A fast event-related design with partial trials was used to separate the BOLD response associated with encoding, maintenance, and retrieval periods of the WM task. Behavioral results showed that subjects who began using cannabis earlier in adolescence had longer reaction times (RT) than those with later initiation. Cannabis age of onset was further associated with reduced posterior parietal cortex (PPC) encoding BOLD activation, which significantly mediated age of onset WM RT associations. However, cannabis age of onset brain-behavior associations did not differ between groups with a single reported use and those with repeated use, suggesting age of onset effects may reflect substance use risk characteristics rather than a developmentally-timed cannabis exposure effect. Within repeated cannabis users, greater levels of total cannabis use were associated with performance-related increases in dorsolateral prefrontal cortex (DLPFC) activation during maintenance. This pattern of significant results remained unchanged with inclusion of demographic and prenatal measures as covariates. Surprisingly, however, at the group level, cannabis users generally performed better than participants who reported never using cannabis (faster RT, higher accuracy). We extend previous investigations by identifying that WM associations with cannabis age of onset may be primary to PPC stimulus encoding activity, while the amount of cannabis use is associated with DLPFC maintenance processes. Poorer performance of participants who reported never using cannabis and the consistency of cannabis age of onset associations across single and repeated users limit interpretation of direct developmental effects of cannabis on WM in adulthood.

Responders to rTMS for depression show increased fronto-midline theta and theta connectivity compared to non-responders

BackgroundRepetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression, but only some individuals respond. Predicting response could reduce patient and clinical burden. Neural activity related to working memory (WM) has been related to mood improvements, so may represent a biomarker for response prediction. Primary hypothesesWe expected higher theta and alpha activity in responders compared to non-responders to rTMS. MethodsFifty patients with treatment resistant depression and twenty controls performed a WM task while electroencephalography (EEG) was recorded. Patients underwent 5–8 weeks of rTMS treatment, repeating the EEG at week 1 (W1). Of the 39 participants with valid WM-related EEG data from baseline and W1, 10 were responders. Comparisons between responders and non-responders were made at baseline and W1 for measures of theta (4–8 Hz), upper alpha (10–12.5 Hz), and gamma (30–45 Hz) power, connectivity, and theta-gamma coupling. The control group's measures were compared to the depression group's baseline measures separately. ResultsResponders showed higher levels of WM-related fronto-midline theta power and theta connectivity compared to non-responders at baseline and W1. Responder's fronto-midline theta power and connectivity was similar to controls. Responders also showed an increase in gamma connectivity from baseline to W1, with a concurrent improvement in mood and WM reaction times. An unbiased combination of all measures provided mean sensitivity of 0.90 at predicting responders and specificity of 0.92 in a predictive machine learning algorithm. ConclusionBaseline and W1 fronto-midline theta power and theta connectivity show good potential for predicting response to rTMS treatment for depression.

Time-Dependent Effects of Acute Exercise on University Students’ Cognitive Performance in Temperate and Cold Environments

Background: Few studies have examined the acute exercise-induced changes in cognitive performance in different thermal environments and the time course effects.Objective: Investigate the time-dependent effects of acute exercise on university students’ processing speed, working memory and cognitive flexibility in temperate and cold environments.Method: Twenty male university students (age 23.5 ± 2.0 years) with moderate physical activity level participated in a repeated-measures within-subjects design. Processing speed, working memory and cognitive flexibility were assessed using CogState test battery at baseline (BASE), followed by a 45-min rest (REST), immediately after (EX) and 30 min after (POST-EX) 30-min moderate-intensity treadmill running in both temperate (TEMP; 25°C) and cold (COLD; 10°C) environments. Mean skin temperature (MST) and thermal sensation (TS) were also recorded. Two-way repeated measures ANOVA was performed to analyze each variable. Spearman’s rho was used to identify the correlations between MST, TS and cognitive performance.Results: Reaction time (RT) of processing speed and working memory decreased immediately after exercise in both conditions (processing speed: p = 0.003; working memory: p = 0.007). The facilitating effects on processing speed disappeared within 30 min after exercise in TEMP (p = 0.163) and COLD (p = 0.667), while improvements on working memory remained 30 min after exercise in TEMP (p = 0.047), but not in COLD (p = 0.663). Though RT of cognitive flexibility reduced in both conditions (p = 0.003), no significance was found between EX and REST (p = 0.135). Increased MST and TS were significantly associated with reductions in processing speed RT (MST: r = -0.341, p < 0.001; TS: r = -0.262, p = 0.001) and working memory RT (MST: r = -0.282, p < 0.001; TS: r = -0.2229, p = 0.005), and improvements in working memory accuracy (MST: r = 0.249, p = 0.002; TS: r = 0.255, p = 0.001).Conclusion: The results demonstrate different time-dependent effects of acute exercise on cognition in TEMP and COLD. Our study reveals facilitating effects of exercise on university students’ processing speed and working memory in both environments. However, in contrast to TEMP, effects on working memory in COLD are transient.

Adolescents newly diagnosed with eating disorders have structural differences in brain regions linked with eating disorder symptoms

Background: Adults with eating disorders (ED) show brain volume reductions in the frontal, insular, cingulate, and parietal cortices, as well as differences in subcortical regions associated with reward processing. However, little is known about the structural differences in adolescents with behavioural indications of early stage ED.Aim: This is the first study to investigate structural brain changes in adolescents newly diagnosed with ED compared to healthy controls (HC), and to study whether ED cognitions correlate with structural changes in adolescents with ED of short duration.Methods: Fifteen adolescent females recently diagnosed with ED, and 28 age-matched HC individuals, were scanned with structural magnetic resonance imaging (MRI). Whole-brain and region-of-interest analyses were conducted using voxel-based morphometry (VBM). ED cognitions were measured with self-report questionnaires and working memory performance was measured with a neuropsychological computerized test.Results and conclusions: The left superior temporal gyrus had a smaller volume in adolescents with ED than in HC, which correlated with ED cognitions (concerns about eating, weight, and shape). Working memory reaction time correlated positively with insula volumes in ED participants, but not HC. In ED, measurements of restraint and obsession was negatively correlated with temporal gyrus volumes, and positively correlated with cerebellar and striatal volumes. Thus, adolescents with a recent diagnosis of ED had volumetric variations in brain areas linked to ED cognitions, obsessions, and working memory. The findings emphasize the importance of early identification of illness, before potential long-term effects on structure and behaviour occur.