Cognitive Function In Healthy Adults Research Articles

Acute effects of mango leaf extract on cognitive function in healthy adults: a randomised, double-blind, placebo-controlled crossover study.

Extracts made from the leaves of the edible mango plant (Mangifera indica L., Anacardiaceae) have a long history of medicinal usage, most likely due to the presence of high levels of mangiferin, a polyphenol compound. Previous research has demonstrated that mango leaf extract (MLE) can beneficially modulate cognitive function in both animals and humans. This study aimed to assess the effects of an acute dose of 300 mg MLE (standardised to contain ≥60% mangiferin) on cognitive performance and mood in healthy adults. In this double-blind, placebo-controlled, crossover study, 114 healthy men and women (18-43 years) received either MLE or a matched placebo at each testing visit (separated by at least 7 days). Cognitive performance (including the cognitive demand battery) and mood were measured at 30, 180, and 300 min post-dose. The results showed that, compared to placebo, the group taking MLE displayed a significant increase in serial 3 s and serial 7 s subtraction errors overall. There were no other significant effects on cognitive performance. The results of the current study suggest that the consumption of 300 mg MLE in the absence of an observed multitasking psychological stressor does not improve cognitive performance or mood at up to 300 min post-dose. Due to the very limited nature of the effects and since they were observed among many analyses, these findings should be treated with caution.Clinical trial registration: http://ClinicalTrials.gov, identifier [NCT05182450].

The effects of insufficient sleep and adequate sleep on cognitive function in healthy adults

Study objectivesAlthough sleep affects a range of waking behaviors, the majority of studies have focused on sleep loss with relatively little attention on sustained periods of adequate sleep. The goal of this study was to use an experimental design to examine the effect of both of these sleep patterns on cognitive performance in healthy adults. MethodsThis study used a randomized crossover design. Participants who regularly slept 7-9 hours/night completed two 6-week intervention conditions, adequate sleep (maintenance of habitual bed/wake times) and insufficient sleep (reduction in sleep of 1.5 hours relative to adequate sleep), separated by a 2-6weeks (median=43days) washout period. Cognitive functioning was evaluated at baseline and endpoint of each intervention using the NIH Toolbox Cognition Battery. General linear models contrasted scores following each condition to the baseline of the first condition; the baseline of the second condition was included to evaluate practice effects. ResultsSixty-five participants (age 35.9 ± 4.9years, 89% women, 52% non-White race/ethnicity) completed study procedures. There was improvement in performance on the List Sorting Working Memory task after the adequate sleep condition that exceeded practice effects. Cognitive performance after insufficient sleep did not reach the level expected with practice and did not differ from baseline. A similar pattern was found on the Flanker Inhibitory Control and Attention task. ConclusionsThese findings contribute to our understanding of the complex interplay between sleep and cognition and demonstrate that consistent, stable sleep of at least 7 hours/night improves working memory and response inhibition in healthy adults. Clinical Trial RegistrationThe manuscript reports on data from two clinical trials: Impact of Sleep Restriction on Performance in Adults (URL: https://clinicaltrials.gov/ct2/show/NCT02960776, ID Number: NCT02960776) and Impact of Sleep Restriction in Women (URL: https://clinicaltrials.gov/ct2/show/NCT02835261, ID Number: NCT02835261).

The impact of sleep quality on cognitive function in healthy adults: A cross-sectional study

The impact of sleep quality on cognitive function in healthy adults: A cross-sectional study

Effects of chocolate on cognitive function in healthy adults: A systematic review and meta-analysis on clinical trials.

Cognitive function is defined as performance in objective tasks that need conscious mind effort. It has been shown that consuming foods rich in flavanols causes neurobiological effects and improves learning, memory, and global cognitive function. This study aimed to investigate the impact of chronic chocolate consumption on cognitive function in healthy adults based on published trials. The PICO strategy was applied to examine the research question in this study. Researchers searched the Web of Science, Science Direct, Pubmed, Scopus, Cochrane Library, and Google Scholar databases. Related articles of randomized controlled trials that evaluated the chronic effect of chocolate on cognitive function were selected (all published from their inception to February 2021). The difference in means of the last and first measurements was the main effect measure between the control and intervention groups. For quantitative data synthesis, weighted mean difference (WMD) and 95% confidence interval (CI) were performed in the random effect model. Of the initial 340 articles identified, seven trials met the eligibility criteria. Chronic chocolate intake significantly reduced executive function time (WMD: -11.77, 95% CI: -22.49, -1.05, p = 0.03) of the participants. Further, the language and executive function (WMD: 6.38, 95% CI: 5.97, 6.80, p < 0.001) was raised by 6.38 times after the intervention with chocolate. We could not perform subgroup analysis due to insufficient trials and significant heterogeneity in some studies. It is concluded that daily consumption of cocoa may provide short and middle-term effects on young adults and make them better cognitive performance in learning, memory, and attention.

A map of evidence using transcranial direct current stimulation (tDCS) to improve cognition in adults with traumatic brain injury (TBI).

Cognition impairments often occur after a traumatic brain injury and occur at higher rates in military members. Cognitive symptoms impair daily function, including balance and life quality, years after the TBI. Current treatments to regain cognitive function after TBI, including medications and cognitive rehabilitation, have shown limited effectiveness. Transcranial direct current stimulation (tDCS) is a low-cost, non-invasive brain stimulation intervention that improves cognitive function in healthy adults and people with neuropsychologic diagnoses beyond current interventions. Despite the available evidence of the effectiveness of tDCS in improving cognition generally, only two small TBI trials have been conducted based on the most recent systematic review of tDCS effectiveness for cognition following neurological impairment. We found no tDCS studies that addressed TBI-related balance impairments. A scoping review using a peer-reviewed search of eight databases was completed in July 2022. Two assessors completed a multi-step review and completed data extraction on included studies using a priori items recommended in tDCS and TBI research guidelines. A total of 399 results were reviewed for inclusion and 12 met the criteria and had data extracted from them by two assessors using Google Forms. Consensus on combined data results included a third assessor when needed. No studies using tDCS for cognition-related balance were found. Guidelines and technology measures increase the identification of brain differences that alter tDCS effects on cognition. People with mild-severe and acute-chronic TBI tolerated and benefited from tDCS. TBI-related cognition is understudied, and systematic research that incorporates recommended data elements is needed to advance tDCS interventions to improve cognition after TBI weeks to years after injury.

The effects of fish oil supplementation on arterial stiffness and cognitive function in healthy adults: a pilot study

Introduction: Elevated aortic and carotid artery stiffness are associated with subclinical brain damage and cognitive impairment. Fish oil (FO) is a popular dietary supplement that lowers blood pressure and aortic stiffness. However, the hypothesis that FO supplementation reduces carotid artery stiffness and improves cognitive function in healthy adults requires further investigation. Our objective was to determine the effects of FO supplementation on arterial stiffness and cognitive function in healthy adults. We hypothesized that 6-weeks of FO supplementation would lower arterial stiffness and improve cognitive function. Methods: 25 healthy adults were enrolled in a randomized, double-blind, placebo-controlled, parallel-arms intervention to investigate the effects of 6-week FO supplementation (4g/day) on vascular and cognitive function. Aortic stiffness was measured using applanation tonometry and quantified as carotid-femoral pulse wave velocity (cfPWV) and beta-stiffness index (bstiff), and carotid artery stiffness was determined using ultrasonography. Cognitive function was assessed using NIH toolbox cognitive battery. A two-way analysis of variance was used to test differences in treatment groups over time. Results: The mean (± SD) baseline age, body mass index, systolic, and diastolic blood pressure was 40.4 ± 20.6 years, 23.7 ± 2.4 kg/m2, 120.9 ± 14.7 mmHg, and 74.9 ± 12.4 mmHg in the fish oil group and 33.3 ± 14.5 years, 25.3 ± 3.9 kg/m2, 120.8 ± 6.4 mmHg, and 71.9 ± 7.8 mmHg in the placebo group, respectively. Compared to the national averages, our participants scored slightly above average (within one standard deviation) on all tests within the NIH cognitive battery. Within-group comparison revealed no differences in central or peripheral blood pressure, aortic or carotid stiffness, and cognitive function after fish oil supplementation (all p&gt;0.05). Conclusion: Our preliminary data suggest that in healthy, cognitively normal adults, 6- weeks of FO supplementation does not impact indices of arterial stiffness or cognitive function. Further investigation with more participants and of longer duration is needed to confirm our findings regarding the effects of fish oil supplementation on carotid artery stiffness and cognitive function. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Effect of Cognitive Training with Neurofeedback on Cognitive Function in Healthy Adults: A Systematic Review and Meta-Analysis

Cognitive training aims to improve cognitive function through cognitive tasks or training games. Neurofeedback is a technique to monitor brain signals with either visual or auditory feedback. Previous studies suggest that a combination of cognitive training and neurofeedback has a superior effect on cognitive functions compared with cognitive training alone. However, no systematic reviews and meta-analyses of the benefits of cognitive training with neurofeedback (CTNF) exist. The purpose of this study was to examine the beneficial effects of CTNF in healthy adults using a systematic review and multilevel meta-analysis. PubMed, Scopus, PsychoINFO, and MEDLINE were searched for research papers reporting the results of interventions using CTNF. After an initial screening of 234 records, three studies using near-infrared spectroscopy (NIRS) and one study using electroencephalography were extracted from the database. We performed a multi-level meta-analysis with three NIRS studies including 166 participants (mean ages ranged from 21.43 to 65.96 years). A multi-level meta-analysis revealed that CTNF has a beneficial effect on the episodic, long-term, and working memory domains. Although three studies were included in the systematic review and meta-analysis, our results indicate that CTNF using NIRS would lead to improvements in memory functioning.

The relationship between spatiotemporal gait parameters and cognitive function in healthy adults: protocol for a cross-sectional study

BackgroundMotor dysfunctions, such as slower walking speed, precede the occurrence of dementia and mild cognitive impairment, suggesting that walking parameters are effective biomarkers for detecting early sub-clinical cognitive risk. It is often also concurrent with self-complained cognitive dysfunction, called motoric cognitive risk (MCR) syndrome. Our preliminary study found several walking parameters, obtained by a three-dimensional motion capture system, to be correlated with computer-based assessments of various cognitive function modalities, although the sample size was small. The Cognitive-Gait (CoGait) Database Project, described in the current protocol, aims to establish a database of multi-dimensional walking and cognitive performance data, collected from a large sample of healthy participants, crucial for detecting early sub-clinical cognitive risk.MethodsWe will recruit healthy volunteers, 20 years or older, without any neurological musculoskeletal or psychiatric disorders. The estimated sample size is 450 participants, including a 10% attrition rate. Using computer-based cognitive assessments, participants will perform six tasks: (i) the simple reaction time task, (ii) Go/No-Go task, (iii) Stroop Color–Word Test, (iv) N-back test, (v) Trail Making Test, and (vi) digit span test. We will also conduct paper-based cognitive assessments such as the Mini-Mental State Examination, Montreal Cognitive Assessment, and the Geriatric Depression Scale-15 for assessing MCR. Gait will be measured through joint kinematics and global positioning in participants’ lower legs while walking at a comfortable and faster pace, using pants with an inertial measurement unit-based three-dimensional motion capture system. Finally, we will establish a prediction model for various cognitive performance modalities based on walking performance.DiscussionThis will be the first study to reveal the relationship between walking and cognitive performance using multi-dimensional data collected from a large sample of healthy adults, from the general population. Despite certain methodological limitations such as the accuracy of measurements, the CoGait database is expected to be the standard value for both walking and cognitive functions, supporting the evaluation of psychomotor function in early sub-clinical cognitive risk identification, including motoric-cognitive risk syndrome.

Systematic Review on the Potential Effect of Berry Intake in the Cognitive Functions of Healthy People.

The increase in life expectancy poses health challenges, such as increasing the impairment of cognitive functions. Berries show a neuroprotective effect thanks to flavonoids, able to reduce neuroinflammatory and to increase neuronal connections. The aim of this systematic review is to explore the impact of berries supplementation on cognitive function in healthy adults and the elderly. Twelve studies were included for a total of 399 participants, aged 18–81 years (mean age: 41.8 ± 4.7 years). Six studies involved young adults (23.9 ± 3.7 years), and four studies involved the elderly (60.6 ± 6.4 years). Most studies investigated effects of a single berry product, but one used a mixture of 4 berries. Non-significant differences were detected across cognition domains and methodologies, but significant and positive effects were found for all cognitive domains (attention and concentration, executive functioning, memory, motor skills and construction, and processing speed), and in most cases they were present in more than one study and detected using different methodologies. Although some limitations should be taken into account to explain these results, the positive findings across studies and methodologies elicit further studies on this topic, to endorse the consumption of berries in healthy populations to prevent cognitive decline.

Effectiveness of Response Inhibition Training and Its Long-Term Effects in Healthy Adults: A Systematic Review and Meta-Analysis.

ObjectiveThis study aims to evaluate the effectiveness and long-term effects of response inhibition training as a therapeutic approach in healthy adults.MethodsThe PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang, and China Science and Technology Journal Database (VIP) were searched for studies. Data on the improvement of Cognitive function and its long-term effect were extracted by two authors independently. The pooled data were meta-analyzed using a random-effects model, and the quality of each eligible study was assessed by The Cochrane Collaboration’s tool.ResultsNine articles were included. 1 of the articles included 2 trials, so 10 eligible trials (response inhibition training group vs. control group) were identified. A total of 490 patients were included. Response inhibition training has beneficial effects on improving cognitive function in healthy adults compared to control treatment (SMD, −0.93; 95% CI, −1.56 to −0.30; Z = 2.88, P = 0.004), the subgroup analysis results showed that either GNG training alone (SMD, −2.27; 95% CI, −3.33 to −1.21; Z = 4.18, P < 0.0001) or the combination of both SST and GNG significantly improved cognitive function in healthy adults (SMD, −0.94; 95% CI, −1.33 to −0.56; Z = 4.80, P < 0.0001), whereas SST training alone did not have such an effect (SMD, −0.15; 95% CI, −0.76 to 0.47; Z = 0.47, P = 0.64). But its long-term effects are not significant (SMD, −0.29; 95% CI, −0.68 to 0.10; Z = 1.45, P = 0.15). The subgroup analysis results showed that neither GNG training alone (SMD, −0.25; 95% CI, −0.75 to 0.24; Z = 0.99, P = 0.32) nor SST training alone (SMD, 0.03; 95% CI, −0.42 to 0.48; Z = 0.14, P = 0.89) could improve the cognitive function of healthy adults in the long term. In contrast, the combination of both training (SMD, −0.95; 95% CI, −1.46 to −0.45; Z = 3.68, P = 0.0002) can have long-term effects on the improvement of cognitive function in healthy adults.ConclusionThe findings of our study indicate that response inhibition training can improve the cognitive function of healthy adults and that more RCTs need to be conducted to validate their usefulness in clinical cases.

Magnitude, timing and duration of mood state and cognitive effects of acute moderate exercise in major depressive disorder

BackgroundAcute exercise generally improves mood state and cognitive functioning in healthy adults. However, the impact of acute exercise on primary symptoms in adults with major depressive disorder (MDD) is poorly understood. The present randomized cross-over study evaluated the magnitude, timing, and duration of the psychological effects of 30 min of moderate-intensity cycling exercise compared to quiet rest in 30 adults (21 female) with MDD. MethodsDepressed mood state (Profile of Mood States Short Form-Depression; POMS-D), state anhedonia (anhedonia Visual Analog Scale [VAS], and Dimensional Anhedonia Rating Scale [DARS]), and cognition (inhibition via Stroop and working memory via the 2-back task) were assessed pre, mid, post, 25-, 50- and 75-min after each session. ResultsGeneralized estimating equations demonstrated significant session by time interactions for POMS-D and VAS indicating small-to-large improvements in mood state and anhedonia up to 75 min post-exercise (p < 0.05; Cohen’s d ranges: POMS [-0.69, -0.95]; DARS, [-0.02, 0.16]; VAS [0.33, 0.83]) with greater immediate effects that lessened somewhat across time. For cognition, Stroop reaction time improved during exercise, but was worse at 25- and 50-min post-exercise compared to quiet rest (p < 0.05); no differences were found for 2-back reaction time. LimitationsThe small sample and continued psychological effects at 75 min indicate a potentially longer-lasting response than was measured herein. ConclusionPerforming short bouts of moderate intensity exercise appears to be effective for management of key symptoms (anhedonia, depressed mood state) in adults with MDD. The time immediately post-exercise may be ideal for performing emotionally challenging tasks and/or tasks where a low symptom severity would be helpful (e.g., psychotherapy).

Effects of transdermal nicotine delivery on cognitive outcomes: A meta-analysis.

By the association of nicotinic acetylcholine receptors in the brain, nicotine in the therapeutic window lowers neuronal damage and raises protective factors. These data, however, are contradicted by other findings. Here, we assessed the effects of transdermal nicotine administration on cognitive functions in healthy non-smoker adults by systematic review and meta-analysis of clinical trials. We included reports of clinical trials comparing the effects of nicotine patches with placebo in healthy non-smoking adults. The main outcome was the impact of nicotine patches on overall cognitive function with a focus on attention and memory. Standard meta-analytic and statistical methods measured the effect of transdermal nicotine compared with placebo patches. We included 31 publications involving 978 subjects. Nicotine patches boosted cognitive function in healthy adults (0.233 SMD, 95%CI, 0.111-0.355, p<.001). Overall heterogeneity of the studies was found to be modest (ϰ2 =68.24, T2 =0.07, I2 =50.17%, p<.001). Also, nicotine patches improved attention (0.231 SMD, 95%CI, 0.106-0.356, p<.001). We found the inter-study heterogeneity to be low (ϰ2 =40.95, T2 =0.03, I2 =34.07%, p=.042). Further, the enhancement of memory by transdermal nicotine did not reach statistical significance in normal subjects (0.270 SMD, 95% CI, -0.293-0.833, p=.347). Also, high inter-study heterogeneity was found among studies (ϰ2 =27.25, T2 =0.43, I2 =77.98%, p<.001). The meta-analysis showed that transdermal nicotine had statistically significant positive effects on attention, and non-significant effects on memory, in healthy non-smoking adults. The results encourage further studies of the therapeutic potential of nicotine patches in disorders of cognition.

β-Lactolin Enhances Neural Activity, Indicated by Event-Related P300 Amplitude, in Healthy Adults: A Randomized Controlled Trial.

Background:Epidemiological studies have shown that dairy product consumption is beneficial for cognitive function in elderly individuals. β-lactolin is a Gly–Thr–Trp–Tyr lacto-tetrapeptide rich in fermented dairy products that improves memory retrieval, attention, and executive function in older adults with subjective cognitive decline and prevents the pathology of Alzheimer’s disease in rodents. There has been no study on the effects of β-lactolin on neural activity in humans.Objective:We investigated the effects of β-lactolin on neural activity and cognitive function in healthy adults.Methods:In this randomized, double-blind, placebo-controlled study, 30 participants (45–64 years old) consumed β-lactolin or placebo for 6 weeks. Neural activity during auditory and language tasks was measured through 64-channel electroencephalography. Moreover, verbal fluency tests were performed at baseline and after 6 weeks.Results:The β-lactolin group had a significantly higher P300 amplitude at the Cp2 site (a part of the parietal lobe near the center of brain, p = 0.011), and C4 site (the area between the frontal and parietal lobe, p = 0.02) during the auditory tasks after 6 weeks than the placebo group. Thus, β-lactolin supplementation promoted neural activity in the parietal area, which increases concentration and attention during auditory cognitive tasks. Compared with the placebo group, the β-lactolin group also showed significant changes in the scores of verbal fluency test after 6 weeks (p = 0.033).Conclusion:Our findings provide insight into the mechanisms underlying the effects of β-lactolin on attention in healthy adults.

Effect of Repeated Anodal HD-tDCS on Executive Functions: Evidence From a Pilot and Single-Blinded fNIRS Study.

Executive functions are of vital importance in the process of active cognition, which is thought to be associated with the dorsolateral prefrontal cortex (DLPFC). As a valid brain stimulation technology, high-definition transcranial direct current stimulation (HD-tDCS) has been used to optimize cognitive function in healthy adults. Substantial evidence indicates that short-term or single anodal tDCS sessions over the left DLPFC will enhance the performance of executive functions. However, the changes in performance and cortical activation of executive functions after modulation by repeated anodal HD-tDCS is as yet unexplored. This study aims to examine changes in three core components of executive functions (inhibitory control, working memory, and cognitive flexibility) produced by nine HD-tDCS sessions (1.5 mA, over left DLPFC, 20 min per session), and to use functional near-infrared spectroscopy (fNIRS) to bilaterally record DLPFC neural activity. A total of 43 participants were divided randomly into two study groups (anodal group vs. sham group) to complete nine interventions. Our results demonstrate that the enhancement of cognitive flexibility in the anodal group was significantly better than that in the sham group. Additionally, a Stroop effect-related decrease in oxygenated hemoglobin (HbO) concentration in the DLPFC was observed in the anodal group but not the sham group. In conclusion, our study found that repeated anodal HD-tDCS sessions can significantly promote cognitive flexibility, one of the core components of executive function, and that alterations in DLPFC activation can enhance our understanding of the neuroplastic modifications modulated by HD-tDCS.

Cognitive complaint and objective cognition during the post-acute period after mild traumatic brain injury in pre-morbidly healthy adults

ABSTRACT Primary Objective: The most widely used proxies of cognitive complaint after mTBI are post-concussion syndrome (PCS) symptom checklists, which do not have a clear relationship with cognition. This study investigated whether an mTBI-specific cognitive complaint measure would have clearer associations with objective cognition than a widely used PCS symptom checklist. Research Design: An observational design was used. A sample of 109 participants (52 mTBI and 57 healthy controls) completed a PCS symptom checklist, a cognitive complaint measure, and measures of information processing speed, attention, memory, executive function, depression and anxiety. Main Outcomes and Results: In the healthy control group, cognitive complaint was significantly associated with objective cognitive performance and was not associated with psychological status. In contrast, PCS endorsement was unrelated to objective cognition but was associated with psychological status. For the mTBI group, neither PCS endorsement nor cognitive complaint was associated with cognitive performance, but both measures were associated with psychological status. Conclusions: This study indicates that neither cognitive nor PCS symptom measures are reliable indicators of underlying cognitive function in the post-acute period after mTBI. Further, suffering an mTBI may affect the linear relationship that exists between cognitive symptom endorsement and cognitive function in healthy adults.

The effect of one-night sleep deprivation on cognitive functions in healthy young adults.

IntroductionThe effects of acute sleep deprivation on cognitive function have not been clearly elucidated. The purpose of this study was to evaluate changes in cognitive function in healthy adults after one night of sleep deprivation.Material and MethodsTwenty-one healthy young adults (aged 18-30 years) underwent assessment of cognitive functions before and after one night of total sleep deprivation and an age- and gender-matched control group was assessed before and after a normal night sleep. Cognitive functions were assessed using the Montreal cognitive assessment (MOCA) and trail making test (TMT) parts A and B.ResultsGeneral linear model repeated measures demonstrated an insignificant effect for time × group (sleep deprivation) interaction for MOCA, TMT Part A, and TMT Part B scores after one-night sleep deprivation (p>.05 for all).ConclusionA single night of sleep deprivation, which can be inevitable in modern society, had no significant effect on cognitive performance in healthy adults.

Effects of a single dose of tablets containing lactononadecapeptide on cognitive function in healthy adults: a randomized, double-blind, cross-over, placebo-controlled trial.

Lactononadecapeptide (LNDP; NIPPLTQTPVVVPPFLQPE) is a memory-improving peptide. The current study aimed to determine the effects of a single dose of tablets containing LNDP on cognitive function in healthy Japanese men aged 30-59 years. A randomized, double-blind, cross-over, placebo-controlled trial was conducted in participants randomly assigned to receive LNDP or placebo tablets. The Uchida-Kraepelin test was used to induce cognitive load in participants as a model of work load. Cognitive function was evaluated using the Japanese version of the CNS Vital Signs. Composite memory and verbal memory were significantly higher following consumption of LNDP than placebo tablets. Carryover effects were observed in attention and concentration domains so that period 1 data was analyzed. LNDP consumption led to higher processing speed, executive function, and cognitive flexibility than placebo. Thus, supplementation with a single dose of LNDP tablets may improve cognitive functions including memory, attention, concentration, and information processing in daily life.

The Modulation of Cognitive Performance with Transcranial Alternating Current Stimulation: A Systematic Review of Frequency-Specific Effects.

Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that allows the manipulation of intrinsic brain oscillations. Numerous studies have applied tACS in the laboratory to enhance cognitive performance. With this systematic review, we aim to provide an overview of frequency-specific tACS effects on a range of cognitive functions in healthy adults. This may help to transfer stimulation protocols to real-world applications. We conducted a systematic literature search on PubMed and Cochrane databases and considered tACS studies in healthy adults (age > 18 years) that focused on cognitive performance. The search yielded n = 109 studies, of which n = 57 met the inclusion criteria. The results indicate that theta-tACS was beneficial for several cognitive functions, including working memory, executive functions, and declarative memory. Gamma-tACS enhanced performance in both auditory and visual perception but it did not change performance in tasks of executive functions. For attention, the results were less consistent but point to an improvement in performance with alpha- or gamma-tACS. We discuss these findings and point to important considerations that would precede a transfer to real-world applications.

Oral administration of porcine liver decomposition product for 4weeks enhances visual memory and delayed recall in healthy adults over 40years of age: A randomized, double-blind, placebo-controlled study.

Porcine liver decomposition product (PLDP) contains neurofunctional phospholipids. We previously reported that PLDP enhances cognitive function in healthy adult humans, based on clinical evaluations using Hasegawa's Dementia Scale-Revised. In this study, we evaluated the effect of PLDP on memory indicators of the Wechsler Memory Scale-Revised (WMS-R), an internationally recognized battery for memory assessment. We conducted a double-blind parallel-group placebo-controlled trial to evaluate the effect of PLDP on memory. Fifty-eight participants competed the trial: 28 participants were in the PLDP group and 30 participants were in the placebo group. Each group was administered PLDP (4 capsules) or a placebo (4 capsules) for 4 continuous weeks. WMS-R was administered before and 4weeks after PLDP or placebo intake. The data were also subdivided by age for participants under 40years (N=15 in PLDP; N=15 in placebo) and over 40years (N=13 in PLDP, N=15 in placebo). Changes in Verbal Memory, Visual Memory, Attention/Concentration, and Delayed Recall were analyzed. No significant differences were found in any memory indicators between the PLDP group and the placebo group in pooled participants and in participants under 40years of age. However, for participants over 40years of age, PLDP administration resulted in a significant enhancement than placebo administration in Delayed Recall (14.1±7.1 points vs. 7.1±6.8 points) (P<0.05), Visual Recall I (20.1±23.1 percentile vs 1.9±22.8 percentile) (P<0.05), and Visual Recall II (24.2±25.8 percentile vs 6.7±19.0 percentile) (P<0.05), respectively. The composition ratio of men to women in each group was imbalanced but no significant difference existed between the two groups. A modest sample size, single-center design, and a fairly short follow-up period. PLDP enhanced Visual Memory and Delayed Recall in healthy adults over 40years of age but not in healthy adults under 40years of age. Therefore, PLDP may represent a promising nutraceutical that could improve cognitive function in healthy adults over 40years of age. Further studies are required to evaluate if long term PLDP administration can prevent or delay cognitive dysfunction in healthy adults over 40years of age.

The Postural Stability Measures Most Related to Aging, Physical Performance, and Cognitive Function in Healthy Adults.

Background Different measures have been used to quantify body balance; some of which use technology to measure postural sway, others are physical performance or self-reported. However, there is little information on the best postural sway measures associated with aging, physical performance, and cognitive function measures. Objective To evaluate the relationship between postural sway measures and aging, physical performance, and cognitive function measures. Methods A total of 51 subjects (53% female, mean age 53.2 ± 21 years) participated in this cross-sectional study. The participants completed the Activities-specific Balance Confidence (ABC) Scale questionnaire, the Functional Gait Assessment (FGA), the Montreal Cognitive Assessment (MoCA) test, and gait speed. Afterward, the participants performed 8 balance exercises, and their postural sway was measured using a force plate. Spearman's rank correlation coefficient was used to examine the relationship between the study variables. Results Age was negatively associated with cognitive function, gait speed, ABC scores, and FGA scores. In addition, cognitive ability was associated positively with ABC scores (r = 0.38, p ≤ 0.01). Age, FGA scores, and gait speed were significantly associated with the postural sway of the AP direction in some exercises and in all exercises in the ML directions (p < 0.05). The cognitive function and ABC scores were significantly associated with only postural sway measures in the ML direction (p < 0.05). Conclusion The postural sway measures in the lateral direction had more and stronger associations with age, physical performance, and cognitive function measures compared to those in the AP direction.