Cortical areas related to performance of WAIS Digit Symbol Test: a functional imaging study

Cognitive function based on theta-gamma coupling vs. clinical diagnosis in older adults with mild cognitive impairment with or without major depressive disorder

Whether individuals with mild cognitive impairment (MCI) and a history of major depressive disorder (MDD) are at a higher risk for cognitive decline than those with MCI alone is still not clear. Previous work suggests that a reduction in prefrontal cortical theta phase-gamma amplitude coupling (TGC) is an early marker of cognitive impairment. This study aimed to determine whether using a TGC cutoff is better at separating individuals with MCI or MCI with remitted MDD (MCI+rMDD) on cognitive performance than their clinical diagnosis. Our hypothesis was that global cognition would differ more between TGC-based groups than diagnostic groups. We analyzed data from 128 MCI (mean age: 71.8, SD: 7.3) and 85 MCI+rMDD (mean age: 70.9, SD: 4.7) participants. Participants completed a comprehensive neuropsychological battery; TGC was measured during the N-back task. An optimal TGC cutoff was determined during the performance of the 2-back. This TGC cutoff was used to classify participants into low vs. high-TGC groups. We then compared Cohen's d of the difference in global cognition between the high and low TGC groups to Cohen's d between the MCI and MCI+rMDD groups. We used bootstrapping to determine 95% confidence intervals for Cohen's d values using the whole sample. As hypothesized, Cohen's d for the difference in global cognition between the TGC groups was larger (0.64 [0.32, 0.88]) than between the diagnostic groups (0.10 [0.004, 0.37]) with a difference between these two Cohen's d's of 0.54 [0.10, 0.80]. Our findings suggest that TGC is a useful marker to identify individuals at high risk for cognitive decline, beyond clinical diagnosis. This could be due to TGC being a sensitive marker of prefrontal cortical dysfunction that would lead to an accelerated cognitive decline.

Assessing processing speed and its neural correlates in the three variants of primary progressive aphasia with a non-verbal tablet-based task

Prior research has revealed distinctive patterns of impaired language abilities across the three variants of Primary Progressive Aphasia (PPA): nonfluent/agrammatic (nfvPPA), logopenic (lvPPA) and semantic (svPPA). However, little is known about whether, and to what extent, non-verbal cognitive abilities, such as processing speed, are impacted in PPA patients. This is because neuropsychological tests typically contain linguistic stimuli and require spoken output, being therefore sensitive to verbal deficits in aphasic patients. The aim of this study is to investigate potential differences in processing speed between PPA patients and healthy controls, and among the three PPA variants, using a brief non-verbal tablet-based task (Match) modeled after the WAIS-III digit symbol coding test, and to determine its neural correlates. Here, we compared performance on the Match task between PPA patients (n = 61) and healthy controls (n = 59) and across the three PPA variants. We correlated performance on Match with voxelwise gray and white matter volumes. We found that lvPPA and nfvPPA patients performed significantly worse on Match than healthy controls and svPPA patients. Worse performance on Match across PPA patients was associated with reduced gray matter volume in specific parts of the left middle frontal gyrus, superior parietal lobule, and precuneus, and reduced white matter volume in the left parietal lobe. To conclude, our behavioral findings reveal that processing speed is differentially impacted across the three PPA variants and provide support for the potential clinical utility of a tabled-based task (Match) to assess non-verbal cognition. In addition, our neuroimaging findings confirm the importance of a set of fronto-parietal regions that previous research has associated with processing speed and executive control. Finally, our behavioral and neuroimaging findings combined indicate that differences in processing speed are largely explained by the unequal distribution of atrophy in these fronto-parietal regions across the three PPA variants.

Low thalamic activity during a digit-symbol substitution task is associated with symptoms of subjective cognitive decline

Introduction

Subjective cognitive decline (SCD) may represent the earliest preclinical stage of Alzheimer's Disease (AD) for some older adults. However, the underlying neurobiology of SCD is not completely understood. Since executive function may be affected earlier than memory function in the progression of AD, we aimed to characterize SCD symptoms in terms of fMRI brain activity during the computerized digit-symbol substitution task (DSST), an executive function task. We also explored associations of DSST task performance with brain activation, SCD severity, and amyloid-ß (Aß) load.

Methods

We analyzed data from 63 cognitively normal older individuals (mean age 73.6 ± 7.2) with varying degree of SCD symptoms. Participants completed a computerized version of DSST in the MR scanner and a Pittsburgh Compound-B (PiB)-PET scan to measure global cerebral Aß load.

Results

A voxel-wise analysis revealed that greater SCD severity was associated with lower dorsomedial thalamus activation. While task performance was not associated with brain activation nor Aß load, slower reaction time was associated with greater SCD severity.

Discussion

The observed lower dorsomedial thalamus activation may reflect declining familiarity-based working memory and the trans-thalamic executive function pathway in SCD. SCD symptoms may reflect altered neural function and subtle decline of executive function, while Aß load may have an indirect impact on neural function and performance. Self-perceived cognitive decline may serve as a psychological/subjective marker reflecting subtle brain changes.

Deconstructing delirium in the post anaesthesia care unit

The course of neuro-cognitive recovery following anaesthesia and surgery is distinctive and poorly understood. Our objective was to identify patterns of neuro-cognitive recovery of the domains routinely assessed for delirium diagnosis in the post anaesthesia care unit (PACU) and to compare them to the cognitive recovery patterns observed in other studies; thereby aiding in the identification of pathological (high risk) patterns of recovery in the PACU. We also compared which of the currently available tests (3D-CAM, CAM-ICU, and NuDESC) is the best to use in PACU. This was a post hoc secondary analysis of data from the Alpha Max study which involved 200 patients aged over 60 years, scheduled for elective surgery under general anaesthesia lasting more than 2 h. These patients were assessed for delirium at 30 min following arrival in the PACU, if they were adequately arousable (Richmond Agitation Sedation Score ≥ −2). All tests for delirium diagnosis (3D-CAM, CAM-ICU, and NuDESC) and the sub-domains assessed were compared to understand temporal recovery of neurocognitive domains. These data were also analysed to determine the best predictor of PACU delirium. We found the incidence of PACU delirium was 35% (3D-CAM). Individual cognitive domains were affected differently. Few individuals had vigilance deficits (6.5%, n = 10 CAM-ICU) or disorganized thinking (19% CAM-ICU, 27.5% 3D-CAM), in contrast attention deficits were common (72%, n = 144) and most of these patients (89.5%, n = 129) were not sedated (RASS ≥ −2). CAM-ICU (27%) and NuDESC (52.8%) detected fewer cases of PACU delirium compared to 3D-CAM. In conclusion, return of neurocognitive function is a stepwise process; Vigilance and Disorganized Thinking are the earliest cognitive functions to return to baseline and lingering deficits in these domains could indicate an abnormal cognitive recovery. Attention deficits are relatively common at 30 min in the PACU even in individuals who appear to be awake. The 3D CAM is a robust test to check for delirium in the PACU.

Acceptability of the Cognition Test Battery in Astronaut and Astronaut-Surrogate Populations

BACKGROUND

Sustained high levels of astronaut cognitive performance are a prerequisite for mission success. A neuropsychological battery of 10 brief cognitive tests (Cognition) covering a range of cognitive domains was specifically developed for high performing astronauts to objectively assess cognitive performance. Extended mission durations require repeated cognitive testing and thus high acceptability of the Cognition software to the astronaut population. The aim of this qualitative study was to evaluate acceptability of Cognition to astronauts and astronaut surrogate populations.

METHODS

Cognition was administered repeatedly to N=87 subjects (mean age ±SD 35.1 ±8.7 years, 52.8% male) on a laptop or iPad across five individual studies on the International Space Station or in space analog environments on Earth. Following completion of each study, participants were interviewed regarding their experience using Cognition in a semi-structured debrief. Participant comments were analyzed using a qualitative conventional content analysis approach.

RESULTS

The majority of participants' comments (86.1%) were coded as positive or neutral in valence, with most positive comments relating to software usability, engagement, and overall design. Among the 10 Cognition tests, subjects liked the Visual Object Learning Test most (28 likes, 32.2% of participants), while the Emotion Recognition Test was liked least (44 dislikes, 50.6% of participants). Some subjects (36.8%) were frustrated with the level of difficulty of some of the 10 Cognition tests, especially during early administrations, which was by design to avoid ceiling effects in repeated administrations of high-performers. Technical difficulties were rare (20.7% of participants), and most often observed in environments with restricted internet access. Most participants (82.3% of those who commented) liked the feedback provided by Cognition after each test, which includes a graph showing performance history.

CONCLUSION

Cognition was found to be acceptable to astronaut and astronaut-surrogate populations across a variety of settings and mission durations. Participant feedback provided was used to further improve Cognition and increase its acceptability during sustained space missions.

OUP accepted manuscript

Mutations of the mitochondrial DNA are an important cause of inherited diseases that can severely affect the tissue’s homeostasis and integrity. The m.3243A > G mutation is the most commonly observed across mitochondrial disorders and is linked to multisystemic complications, including cognitive deficits. In line with in vitro experiments demonstrating the m.3243A > G’s negative impact on neuronal energy production and integrity, m.3243A > G patients show cerebral grey matter tissue changes. However, its impact on the most neuron dense, and therefore energy-consuming brain structure—the cerebellum—remains elusive. In this work, we used high-resolution structural and functional data acquired using 7 T MRI to characterize the neurodegenerative and functional signatures of the cerebellar cortex in m.3243A > G patients. Our results reveal altered tissue integrity within distinct clusters across the cerebellar cortex, apparent by their significantly reduced volume and longitudinal relaxation rate compared with healthy controls, indicating macroscopic atrophy and microstructural pathology. Spatial characterization reveals that these changes occur especially in regions related to the frontoparietal brain network that is involved in information processing and selective attention. In addition, based on resting-state functional MRI data, these clusters exhibit reduced functional connectivity to frontal and parietal cortical regions, especially in patients characterized by (i) a severe disease phenotype and (ii) reduced information-processing speed and attention control. Combined with our previous work, these results provide insight into the neuropathological changes and a solid base to guide longitudinal studies aimed to track disease progression.

Distinct neuroanatomic subtypes in antipsychotic-treated patients with schizophrenia classified by the predefined classification in a never-treated sample

Background

Distinct neuroanatomic subtypes have been identified in never-treated patients with schizophrenia based on cerebral structural abnormalities, but whether antipsychotic-treated patients would be stratified under the guidance of such previously formed classification remains unclear.

Objective

The present study aimed to investigate alterations of brain structures in antipsychotic-treated patients with schizophrenia based on a predefined morphological classification and their relationships with cognitive performance.

Methods

Cortical thickness, surface area, and subcortical volume were extracted from 147 antipsychotic-treated patients with schizophrenia using structural magnetic resonance imaging for classification. The Brief Assessment of Cognition in Schizophrenia (BACS) and Positive and Negative Syndrome Scale (PANSS) were used to assess cognition and symptoms.

Results

Antipsychotic-treated patients were categorized into three subtypes with distinct patterns of brain morphological alterations. Subtypes 1 and 2 were characterized by widespread deficits in cortical thickness but relatively limited deficits in surface area. In contrast, subtype 3 demonstrated cortical thickening mainly in parietal-occipital regions and widespread deficits in surface area. All three subgroups demonstrated cognitive deficits compared with healthy controls. Significant associations between neuroanatomic and cognitive abnormalities were only observed in subtype 1, where cortical thinning in the left lingual gyrus was conversely related to symbol coding performance.

Conclusions

Similar to drug-naïve patients, neuroanatomic heterogeneity exists in antipsychotic-treated patients, with disparate associations with cognition. These findings promote our understanding of relationships between neuroanatomic abnormalities and cognitive performance in the context of heterogeneity. Moreover, these results suggest that neurobiological heterogeneity needs to be considered in cognitive research in schizophrenia.

Short-term ketone monoester supplementation improves cerebral blood flow and cognition in obesity: A randomized cross-over trial

Adults with obesity are at increased risk of neurocognitive impairments, partly as a result of reduced cerebral blood flow and brain-derived neurotrophic factor (BDNF). Ketone supplements containing β-hydroxybutyrate (β-OHB) are a purported therapeutic strategy for improving brain health in at-risk populations. We tested the hypothesis that short-term β-OHB supplementation will elevate cerebral blood flow and BDNF, as well as improve cognition in adults with obesity. In a placebo-controlled double-blind, cross-over design, 14 adults with obesity (10 females; aged 56 ± 12 years; body mass index = 33.8 ± 6.9 kg m^-2 ) consumed 30 mL (12 g) of β-OHB or placebo thrice-daily for 14 days. Blood flow (Q) and cerebrovascular conductance (CVC) were measured in the common carotid (CCA), internal carotid (ICA) and vertebral (VA) arteries by duplex ultrasound. BDNF was measured by an enzyme-linked immunosorbent assay. Cognition was assessed by the digit-symbol substitution (DSST), Stroop and task-switching tests. Following 14 days of ketone supplementation, we observed significant improvements in cerebrovascular outcomes including Q_CCA (+12%), Q_VA (+11%), VA_CVC (+12%) and VA shear rate (+10%). DSST performance significantly improved following ketone supplementation (+2.7 correct responses) and improved DSST performance was positively associated improvements in cerebrovascular outcomes including Q_CCA , CCA_CVC , Q_VA and VA_CVC . By contrast to one hypothesis, β-OHB did not impact fasting serum and plasma BDNF. β-OHB supplementation improved cognition in adults with obesity, which may be partly facilitated by improvements in cerebral blood flow. β-OHB supplementation was well-tolerated and appears to be safe for cerebrovascular health, suggesting potential therapeutic benefits of β-OHB in a population at risk of neurocognitive impairment. KEY POINTS: People with obesity are at increased risk of neurocognitive dysfunction, partly as a result of -induced reductions in cerebral blood flow (CBF) and brain-derived neurotrophic factor (BDNF). Ketone supplements containing β-hydroxybutyrate (β-OHB) reduce postprandial hyperglycaemia, which may increase CBF and BDNF, thereby protecting against obesity-related cognitive dysfunction. We show for the first time that 14 days of thrice-daily β-OHB supplementation improves aspects of cognition and increases cerebrovascular flow, conductance and shear rate in the extracranial arteries of adults with obesity. Our preliminary data indicate a significant positive relationship between elevated CBF and improved cognition following β-OHB supplementation. This trial provides a foundation for the potential non-pharmacological therapeutic application of β-OHB supplementation in patient groups at risk of hyperglycaemic cerebrovascular disease and cognitive dysfunction.

Interindividual differences in attentional vulnerability moderate cognitive performance during sleep restriction and subsequent recovery in healthy young men

We investigated whether interindividual attentional vulnerability moderates performance on domain-specific cognitive tasks during sleep restriction (SR) and subsequent recovery sleep. Fifteen healthy men (M ± SD, 22.3 ± 2.8 years) were exposed to three nights of baseline, five nights of 5-h time in bed SR, and two nights of recovery sleep. Participants completed tasks assessing working memory, visuospatial processing, and processing speed approximately every two hours during wake. Analyses examined performance across SR and recovery (linear predictor day or quadratic predictor day²) moderated by attentional vulnerability per participant (difference between mean psychomotor vigilance task lapses after the fifth SR night versus the last baseline night). For significant interactions between day/day² and vulnerability, we investigated the effect of day/day² at 1 SD below (less vulnerable level) and above (more vulnerable level) the mean of attentional vulnerability (N = 15 in all analyses). Working memory accuracy and speed on the Fractal 2-Back and visuospatial processing speed and efficiency on the Line Orientation Task improved across the entire study at the less vulnerable level (mean − 1SD) but not the more vulnerable level (mean + 1SD). Therefore, vulnerability to attentional lapses after SR is a marker of susceptibility to working memory and visuospatial processing impairment during SR and subsequent recovery.

Cognitive functioning in progressive myoclonus epilepsy type 1 (Unverricht-Lundborg Disease, EPM1)

OBJECTIVE

The aim of this neuropsychological study of a large cohort of patients with progressive myoclonus epilepsy type 1 (Unverricht-Lundborg disease, EPM1) was to characterize the cognitive function of EPM1 patients and to explore the association between the disability caused by the disease and cognitive performance.

METHOD

Sixty-eight genetically verified EPM1 patients homozygous for the expansion mutation in the CSTB gene (37 males and 31 females aged 35 ± 11) participated in a neuropsychological assessment of intellectual ability, verbal memory, and executive and psychomotor function. The clinical evaluation comprised administering (and video-recording) the unified myoclonus rating scale (UMRS) to assess the severity of each patient's myoclonus. Forty-six healthy volunteers (19 males and 27 females aged 32 ± 11) served as the control group for the neuropsychological tests.

RESULTS

The cognitive performance of the EPM1 patient group was impaired. Verbal Intelligence Quotient (VIQ) was below the average range (VIQ < 85) in 49% of the patients; further, Performance Intelligence Quotient (PIQ) was below average in 75% of the patients. The patients performed worse than the controls in both immediate and delayed story recall (p = 0.001); however, in the word list learning task, the patients performed only slightly worse than the controls. The one-hour delayed recall of the learned words was similar in both groups, and the percentage of retained words and story contents did not differ between the patients and controls. The patients were impaired in all of the executive function tests as well as in the psychomotor speed tests (p < 0.001 for all). Also, the patients' simple psychomotor speed in the tapping task was significantly slowed in comparison to controls (p < 0.001).

CONCLUSION

The patients had impaired performance in the majority of the cognitive measures; they showed the highest level of impairment in all the executive function tests and in the psychomotor speed tests. The measures of these cognitive domains are timed-therefore, it is clear that severe myoclonus limits patients' performance. In contrast, verbal memory, especially delayed recall, was the least affected cognitive domain.

Recovery of consciousness and cognition after general anesthesia in humans

Understanding how the brain recovers from unconsciousness can inform neurobiological theories of consciousness and guide clinical investigation. To address this question, we conducted a multicenter study of 60 healthy humans, half of whom received general anesthesia for 3 hr and half of whom served as awake controls. We administered a battery of neurocognitive tests and recorded electroencephalography to assess cortical dynamics. We hypothesized that recovery of consciousness and cognition is an extended process, with differential recovery of cognitive functions that would commence with return of responsiveness and end with return of executive function, mediated by prefrontal cortex. We found that, just prior to the recovery of consciousness, frontal-parietal dynamics returned to baseline. Consistent with our hypothesis, cognitive reconstitution after anesthesia evolved over time. Contrary to our hypothesis, executive function returned first. Early engagement of prefrontal cortex in recovery of consciousness and cognition is consistent with global neuronal workspace theory.

Two-year neurocognitive responses to first occupational lead exposure

Objectives Lead exposure causes neurocognitive dysfunction in children, but its association with neurocognition in adults at current occupational exposure levels is uncertain mainly due to the lack of longitudinal studies. In the Study for Promotion of Health in Recycling Lead (NCT02243904), we assessed the two-year responses of neurocognitive function among workers without previous known occupational exposure newly hired at lead recycling plants. Methods Workers completed the digit-symbol test (DST) and Stroop test (ST) at baseline and annual follow-up visits. Blood lead (BL) was measured by inductively coupled plasma mass spectrometry (detection limit 0.5 µg/dL). Statistical methods included multivariable-adjusted mixed models with participants modelled as random effect. Results DST was administered to 260 participants (11.9% women; 46.9%/45.0% whites/Hispanics; mean age 29.4 years) and ST to 168 participants. Geometric means were 3.97 and 4.13 µg/dL for baseline BL, and 3.30 and 3.44 for the last-follow-up-to-baseline BL ratio in DST and ST cohorts, respectively. In partially adjusted models, a doubling of the BL ratio was associated with a 0.66% [95% confidence interval (CI) 0.03-1.30; P=0.040] increase in latency time (DST) and a 0.35% (95% CI ‑1.63-1.63; P=0.59) decrease in the inference effect (ST). In fully adjusted models, none of the associations of the changes in the DST and ST test results with the blood lead changes reached statistical significance (P≥0.12). Conclusions An over 3-fold increase in blood lead over two years of occupational exposure was not associated with a relevant decline in cognitive performance.

Continuous and Intermittent Artificial Gravity as a Countermeasure to the Cognitive Effects of 60 Days of Head-Down Tilt Bed Rest

Environmental and psychological stressors can adversely affect astronaut cognitive performance in space. This study used a 6° head-down tilt bed rest (HDBR) paradigm to simulate some of the physiologic changes induced by microgravity. Twenty-four participants (mean ± SD age 33.3 ± 9.2 years, N = 16 men) spent 60 consecutive days in strict HDBR. They were studied in three groups of eight subjects each. One group served as Control, whereas the other two groups received either a continuous or intermittent artificial gravity (AG) countermeasure of 30 min centrifugation daily (1 g acceleration at the center of mass and 2 g at the feet). Participants performed all 10 tests of NASA’s Cognition battery and a brief alertness and mood survey repeatedly before, during, and after the HDBR period. Test scores were adjusted for practice and stimulus set difficulty effects. A modest but statistically significant slowing across a range of cognitive domains was found in all three groups during HDBR compared to baseline, most consistently for sensorimotor speed, whereas accuracy was unaffected. These changes were observed early during HDBR and did not further worsen or improve with increasing time in HDBR, except for emotion recognition performance. With increasing time spent in HDBR, participants required longer time to decide which facial emotion was expressed. They were also more likely to select categories with negative valence over categories with neutral or positive valence. Except for workload, which was rated lower in the Control group, continuous or intermittent AG did not modify the effect of HDBR on cognitive performance or subjective responses. Participants expressed several negative survey responses during HDBR relative to baseline, and some of the responses further deteriorated during recovery, which highlights the importance of adequate medical and psychological support during extended duration HDBR studies. In conclusion, 60 days of HDBR were associated with moderate cognitive slowing and changes in emotion recognition performance, but these effects were not mitigated by either continuous or intermittent exposure to AG for 30 min daily.

Effects of head-down tilt bed rest plus elevated CO2 on cognitive performance

Microgravity and elevated CO₂ levels are two important environmental spaceflight stressors that can adversely affect astronaut cognitive performance and jeopardize mission success. This study investigated the effects of 6° head-down tilt bed rest (HDBR) with (n = 11 participants, 30-day HDBR) and without (n = 8 participants, 60-day HDBR) elevated ambient (3.73 mmHg) CO₂ concentrations on cognitive performance. Participants of both groups performed all 10 tests of NASA's Cognition battery and a brief alertness and mood survey repeatedly before, during, and after the HDBR period. Test scores were adjusted for practice and stimulus set effects. Concentrating on the first 30 days of HDBR, a modest but statistically significant slowing across a range of cognitive domains was found in both groups (controls: -0.37 SD; 95% CI -0.48, -0.27; adjusted P < 0.0001; CO₂: -0.25 SD; 95% CI -0.34, -0.16; adjusted P < 0.001), most prominently for sensorimotor speed. These changes were observed early during HDBR and did not further deteriorate or improve with increasing time in HDBR. The study found similar cognitive effects of HDBR irrespective of CO₂ levels, suggesting that elevated CO₂ neither ameliorated nor worsened the HDBR effects. In both groups, cognitive performance after 15 days of recovery was statistically indistinguishable from pre-HDBR performance. However, subjects undergoing 60 days of HDBR rated themselves as feeling more sleepy, tired, physically exhausted, stressed, and unhealthy during recovery compared to their 30-day counterparts.NEW AND NOTEWORTHY This study investigated the effects of prolonged head-down tilt bed rest with and without elevated (3.73 mmHg) levels of ambient CO₂ on cognitive performance across a range of cognitive domains and is one of the few studies investigating combined effects of environmental stressors prevalent in spaceflight. The study showed moderate declines in cognitive speed induced by head-down tilt bed rest and suggests that exposure to elevated levels of ambient CO₂ did not modify this effect.

Changes in Subjective Motivation and Effort During Sleep Restriction Moderate Interindividual Differences in Attentional Performance in Healthy Young Men

PURPOSE

The effects of sleep restriction on subjective alertness, motivation, and effort vary among individuals and may explain interindividual differences in attention during sleep restriction. We investigated whether individuals with a greater decrease in subjective alertness or motivation, or a greater increase in subjective effort (versus other participants), demonstrated poorer attention when sleep restricted.

PARTICIPANTS AND METHODS

Fifteen healthy men (M±SD, 22.3±2.8 years) completed a study with three nights of 10-hour time in bed (baseline), five nights of 5-hour time in bed (sleep restriction), and two nights of 10-hour time in bed (recovery). Participants completed a 10-minute psychomotor vigilance task (PVT) of sustained attention and rated alertness, motivation, and effort every two hours during wake (range: 3-9 administrations on a given day). Analyses examined performance across the study (first two days excluded) moderated by per-participant change in subjective alertness, motivation, or effort from baseline to sleep restriction. For significant interactions, we investigated the effect of study day² (day*day) on the outcome at low (mean-1 SD) and high (mean+1 SD) levels of the moderator (N = 15, all analyses).

RESULTS

False starts increased across sleep restriction in participants who reported lower (mean-1 SD) but not preserved (mean+1 SD) motivation during sleep restriction. Lapses increased across sleep restriction regardless of change in subjective motivation, with a more pronounced increase in participants who reported lower versus preserved motivation. Lapses increased across sleep restriction in participants who reported higher (mean+1 SD) but not preserved (mean-1 SD) effort during sleep restriction. Change in subjective alertness did not moderate the effects of sleep restriction on attention.

CONCLUSION

Vigilance declines during sleep restriction regardless of change in subjective alertness or motivation, but individuals with reduced motivation exhibit poorer inhibition. Individuals with preserved subjective alertness still perform poorly during sleep restriction, while those reporting additional effort demonstrate impaired vigilance.

Interplay of White Matter Hyperintensities, Cerebral Networks, and Cognitive Function in an Adult Population: Diffusion-Tensor Imaging in the Maastricht Study

Background Lesions of cerebral small vessel disease, such as white matter hyperintensities (WMHs) in individuals with cardiometabolic risk factors, interfere with the trajectories of the white matter and eventually contribute to cognitive decline. However, there is no consensus yet about the precise underlying topological mechanism. Purpose To examine whether WMH and cognitive function are associated and whether any such association is mediated or explained by structural connectivity measures in an adult population. In addition, to investigate underlying local abnormalities in white matter by assessing the tract-specific WMH volumes and their tract-specific association with cognitive function. Materials and Methods In the prospective type 2 diabetes-enriched population-based Maastricht Study, structural and diffusion-tensor MRI was performed (December 2013 to February 2017). Total and tract-specific WMH volumes; network measures; cognition scores; and demographic, cardiovascular, and lifestyle characteristics were determined. Multivariable linear regression and mediation analyses were used to investigate the association of WMH volume, tract-specific WMH volumes, and network measures with cognitive function. Associations were adjusted for age, sex, education, diabetes status, and cardiovascular risk factors. Results A total of 5083 participants (mean age, 59 years ± 9 [standard deviation]; 2592 men; 1027 with diabetes) were evaluated. Larger WMH volumes were associated with stronger local (standardized β coefficient, 0.065; P < .001), but not global, network efficiency and lower information processing speed (standardized β coefficient, -0.073; P < .001). Moreover, lower local efficiency (standardized β coefficient, -0.084; P < .001) was associated with lower information processing speed. In particular, the relationship between WMHs and information processing speed was mediated (percentage mediated, 7.2% [95% CI: 3.5, 10.9]; P < .05) by the local network efficiency. Finally, WMH load was larger in the white matter tracts important for information processing speed. Conclusion White matter hyperintensity volume, local network efficiency, and information processing speed scores are interrelated, and local network properties explain lower cognitive performance due to white matter network alterations. © RSNA, 2020 Online supplemental material is available for this article.

Cognition Test Battery Performance Is Associated with Simulated 6df Spacecraft Docking Performance

INTRODUCTION: Environmental and operational stressors commonly encountered in spaceflight can affect astronaut cognitive performance. It is currently unclear how performance decrements on test batteries that assess individual cognitive domains translate to complex operational performance.METHODS: N 30 healthy adults (mean SD age 33.5 7.1 yr, range 2548 yr; 16 men) with demographic characteristics similar to astronauts performed all 10 tests of the Cognition test battery as well as a simulated 6 degrees-of-freedom (6df) spacecraft docking task 15 times. Performance on 60 Cognition outcome variables was rank-correlated with 6df docking performance individually as well as in models containing up to 12 predictors after accounting for sex, age, and study design effects.RESULTS: Average response time on the Digit Symbol Substitution Test (DSST)a measure of processing speed requiring complex scanning, visual tracking, and working memorywas the best individual predictor of 6df docking performance (unadjusted r 0.550; semipartial cross-validated R² 0.244). Furthermore, higher levels of spatial orientation efficiency and vigilant attention, lower levels of impulsivity, and faster response speed were associated with higher 6df performance, while sensorimotor speed, memory, and risk decision making were less relevant. After semipartial cross-validation, a model with three Cognition outcomes (DSST average response time, Abstract Matching accuracy, and conservative response bias on the Fractal 2-Back test) explained 30% of the variance in 6df performance.CONCLUSIONS: This study demonstrates direct links between performance on tests designed to assess specific cognitive domains and complex operational docking performance.Basner M, Moore TM, Hermosillo E, Nasrini J, Dinges DF, Gur RC, Johannes B. Cognition test battery performance is associated with simulated 6df spacecraft docking performance. Aerosp Med Hum Perform. 2020; 91(11):861867.

The impact of BDNF Val66Met on cognitive skills in veterans with posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a trauma-induced disorder characterized with impaired cognitive function. BDNF modulates cognition and is involved in neuroprotection and neurocognitive processing. The BDNF Val66Met polymorphism was found to influence cognitive functions. In PTSD, carriers of the BDNF GG genotype had better spatial processing of navigation performance, and lower hyperarousal and startle reaction than A allele carriers. The hypothesis was that veterans with PTSD, carriers of the BDNF Val66Met A allele, will show reduced cognitive skills. The study included 315 male Caucasian combat veterans, with (N = 199) or without (N = 116) current and chronic PTSD. Cognition was assessed using the Rey-Osterrieth Complex Figure (ROCF) test that determines visual-spatial perception and short and long-term visual memory function. The results revealed that cognitive decline measured with ROCF test was associated with PTSD. Presence of the BDNF Val66Met GG genotype in veterans with PTSD, but not in veterans without PTSD, showed protective association with visual short-term memory and visual object manipulation after few seconds (executive function), assessed with the ROCF immediate recall test, compared to the A carriers with PTSD. In conclusion, this was the first study to confirm the association between BDNF Val66Met and memory and attention performed with ROCF in male veterans with PTSD. The results corroborated that the BDNF Val66Met A allele, compared to GG genotype, is associated with poorer short-term visual memory and attention linked with executive functions, in veterans with PTSD.

Cognition test battery: Adjusting for practice and stimulus set effects for varying administration intervals in high performing individuals

INTRODUCTION

Practice effects associated with the repeated administration of cognitive tests often confound true therapeutic or experimental effects. Alternate test forms help reduce practice effects, but generating stimulus sets with identical properties can be difficult. The main objective of this study was to disentangle practice and stimulus set effects for Cognition, a battery of 10 brief cognitive tests specifically designed for high-performing populations with 15 unique versions for repeated testing. A secondary objective was to investigate the effects of test-retest interval on practice effects.

METHODS

The 15 versions of Cognition were administered in three groups of 15-16 subjects (total N = 46, mean±SD age 32.5 ± 7.2 years, range 25-54 years, 23 male) in a randomized but balanced fashion with administration intervals of ≥10 days, ≤5 days, or 4 times per day. Mixed effect models were used to investigate linear and logarithmic trends across repeated administrations in key speed and accuracy outcomes, whether these trends differed significantly between administration interval groups, and whether stimulus sets differed significantly in difficulty.

RESULTS

Protracted, non-linear practice effects well beyond the second administration were observed for most of the 10 Cognition tests both in accuracy and speed, but test-retest administration interval significantly affected practice effects only for 3 out of the 10 tests and only in the speed domain. Stimulus set effects were observed for the 6 Cognition tests that use unique sets of stimuli. Factors were established that allow for correcting for both practice and stimulus set effects.

CONCLUSIONS

Practice effects are pronounced and probably under-appreciated in cognitive testing. The correction factors established in this study are a unique feature of the Cognition battery that can help avoid masking practice effects, address noise generated by differences in stimulus set difficulty, and facilitate interpretation of results from studies with repeated assessments.

Combined Scores from the EncephalApp Stroop Test, Number Connection Test B, and Serial Dotting Test Accurately Identify Patients With Covert Hepatic Encephalopathy

BACKGROUND & AIMS

The EncephalApp Stroop test is a high-sensitivity but low-specificity test that has been used to identify patients with covert hepatic encephalopathy (CHE). We aimed to develop a new strategy to detect CHE, combining EncephalApp Stroop test score with scores from subtests of the psychometric hepatic encephalopathy scoring system (PHES).

METHODS

We performed a survey of 569 adult volunteers (229 men) in 9 communities in Shanghai, China, administering the EncephalApp Stroop test to determine the range of scores in the general population. Data from the standard PHES, including the number connection test-A, number connection test-B (NCT-B), line tracing test, serial dotting test (SDT), and digit symbol test, were used as the reference standard for diagnosis of CHE. A combination of the EncephalApp Stroop with subtests of the PHES was used to establish a new strategy for CHE diagnosis. We validated our findings using data from 160 patients with cirrhosis from 5 centers China.

RESULTS

We determined the range of EncephalApp Stroop test scores for the volunteers of different decades of age, education levels, and sexes. Age, education level, and sex were independently associated with EncephalApp Stroop test scores. A combination of scores from the EncephalApp Stroop test, the NCT-B, and the SDT identified patients with CHE with the highest level of accuracy, when the standard PHES was used as the reference standard. A combination of scores of 187 sec for the EncephalApp Stroop test and below -1 for the NCT-B or below -1 for the SDT identified patients with CHE with an area under the curve (AUC) of 0.86, 81.0% sensitivity, and 91.9% specificity, and 87.5% accuracy. In the validation cohort, these cutoff scores identified patients with CHE with an AUC of 0.88, 97.1% sensitivity, 79.3% specificity, and 86.9% accuracy. The average time to calculate this score was 374±140 sec, compared 424±115 sec for the entire PHES.

CONCLUSION

Scores from the EncephalApp Stroop test, NCT-B, and SDT identify patients with CHE with approximately 87% accuracy, and in a much shorter time than the standard PHES. This score combination could be a valid and convenient method for identifying patients with CHE. chictr.org.cn number, ChiCTR-EDC-17012007, ChiCTR1800019954.

Acute aerobic exercise impairs aspects of cognitive function at high altitude

Hypoxia-mediated cognitive dysfunction can be transiently mitigated by exercise in a laboratory-based setting. Whether this effect holds true in the context of high altitude hypoxia has not been determined. We investigated the effect of acute aerobic exercise on cognitive function (CF) at low (1400m) and high altitude (4240m). Fifteen volunteers (24.1±3.5yrs; 9 females) exercised for 20-min at 40-60% of their heart rate reserve at low and high altitude. CF was assessed before and 10-min after exercise using a tablet-based battery of executive function tests. A sea-level control group (n=13; 24.2±2.4 years; 9 females) performed time-matched CF tests to assess the contribution of a learning effects due to repeated testing. Measures of resting CF were unaffected by ascent to high altitude. Following high altitude exercise, performance significantly worsened on the digit symbol substitution task - a test of processing speed, working memory, and visuospatial attention (z=0.01 vs. -0.59, p=0.02, η²=0.35). No effect was found on other measures of CF following exercise. There was no association between changes in peripheral oxygen saturation and changes in CF following high altitude exercise (r=0.22, p=0.44), but higher hemoglobin concentration at high altitude was associated with a decline in CF following exercise at high altitude (r=-0.65, p=0.02). Acute aerobic exercise performed at high altitude impairs some aspects of CF, whereas other CF tests remain unchanged. The strong ecological validity of this study warrants attention and follow-up investigations are needed to better characterize selective impairment of CF with high altitude exercise.

The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight

To understand the health impact of long-duration spaceflight, one identical twin astronaut was monitored before, during, and after a 1-year mission onboard the International Space Station; his twin served as a genetically matched ground control. Longitudinal assessments identified spaceflight-specific changes, including decreased body mass, telomere elongation, genome instability, carotid artery distension and increased intima-media thickness, altered ocular structure, transcriptional and metabolic changes, DNA methylation changes in immune and oxidative stress-related pathways, gastrointestinal microbiota alterations, and some cognitive decline postflight. Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within 6 months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. These multiomic, molecular, physiological, and behavioral datasets provide a valuable roadmap of the putative health risks for future human spaceflight.

Neurocognition in PTSD: Treatment Insights and Implications

Post-traumatic stress disorder (PTSD) is classified as a traumatic stress-related condition and is most often discussed in terms of emotional dysfunction. However, given that cognitive and emotional processes are intricately intertwined, implemented by overlapping brain networks, and effectively integrated in at least some of the same regions (e.g., prefrontal cortex, for a review, see Crocker et al. 2013), an abundance of literature now highlights the key role that cognitive functioning plays in both the development and maintenance (or exacerbation) of PTSD symptoms (Aupperle et al. 2012a; Verfaellie et al. 2012). Findings from this body of work detail objective impairment in neuropsychological function in those with PTSD (Brandes et al. 2002; Hayes et al. 2012a; Koenen et al. 2001). Yet despite the impact of neurocognition on PTSD treatment engagement and success (e.g., Haaland et al. 2016; Nijdam et al. 2015) and conversely, the role of PTSD treatment in normalizing cognitive dysfunction, a much smaller literature exists on neurocognitive changes following treatment for PTSD. Even aside from its role in treatment, cognitive functioning in PTSD has significant implications for daily functioning for individuals with this disorder, as cognition is predictive of school achievement, obtaining and maintaining employment, job advancement, maintaining relationships, greater wealth, and better health and quality of life (e.g., Diamond and Ling 2016).

Effects of −12° head-down tilt with and without elevated levels of CO2 on cognitive performance: the SPACECOT study

Microgravity and elevated levels of CO2 are two common environmental stressors in spaceflight that may affect cognitive performance of astronauts. In this randomized, double-blind, crossover trial (SPACECOT), 6 healthy males (mean ± SD age: 41 ± 5 yr) were exposed to 0.04% (ambient air) and 0.5% CO2 concentrations during 26.5-h periods of −12° head-down tilt (HDT) bed rest with a 1-wk washout period between exposures. Subjects performed the 10 tests of the Cognition Test Battery before and on average 0.1, 5.2, and 21.0 h after the initiation of HDT bed rest. HDT in ambient air induced a change in response strategy, with increased response speed (+0.19 SD; P = 0.0254) at the expense of accuracy (−0.19 SD; P = 0.2867), resulting in comparable cognitive efficiency. The observed effects were small and statistically significant for cognitive speed only. However, even small declines in accuracy can potentially cause errors during mission-critical tasks in spaceflight. Unexpectedly, exposure to 0.5% CO2 reversed the response strategy changes observed under HDT in ambient air. This was possibly related to hypercapnia-induced cerebrovascular reactivity that favors cortical regions in general and the frontal cortex in particular, or to the CNS arousing properties of mildly to moderately increased CO2 levels. There were no statistically significant time-in-CO2 effects for any cognitive outcome. The small sample size and the small effect sizes are major limitations of this study and its findings. The results should not be generalized beyond the group of investigated subjects until they are confirmed by adequately powered follow-up studies.

NEW & NOTEWORTHY Simulating microgravity with exposure to 21 h of −12° head-down tilt bed rest caused a change in response strategy on a range of cognitive tests, with a statistically significant increase in response speed at the expense of accuracy. Cognitive efficiency was not affected. The observed speed-accuracy tradeoff was small but may nevertheless be important for mission-critical tasks in spaceflight. Importantly, the change in response strategy was reversed by increasing CO2 concentrations to 0.5%.

Effects of hypoglycaemia on working memory and regional cerebral blood flow in type 1 diabetes: a randomised, crossover trial

AIMS/HYPOTHESIS

The aim of this randomised, crossover trial was to compare cognitive functioning and associated brain activation patterns during hypoglycaemia (plasma glucose [PG] just below 3.1 mmol/l) and euglycaemia in individuals with type 1 diabetes mellitus.

METHODS

In this patient-blinded, crossover study, 26 participants with type 1 diabetes mellitus attended two randomised experimental visits: one hypoglycaemic clamp (PG 2.8 ± 0.2 mmol/l, approximate duration 55 min) and one euglycaemic clamp (PG 5.5 mmol/l ± 10%). PG levels were maintained by hyperinsulinaemic glucose clamping. Cognitive functioning was assessed during hypoglycaemia and euglycaemia conditions using a modified version of the digit symbol substitution test (mDSST) and control DSST (cDSST). Simultaneously, regional cerebral blood flow (rCBF) was measured in pre-specified brain regions by six H₂¹⁵O-positron emission tomographies (PET) per session.

RESULTS

Working memory was impaired during hypoglycaemia as indicated by a statistically significantly lower mDSST score (estimated treatment difference [ETD] -0.63 [95% CI -1.13, -0.14], p = 0.014) and a statistically significantly longer response time (ETD 2.86 s [7%] [95% CI 0.67, 5.05], p = 0.013) compared with euglycaemia. During hypoglycaemia, mDSST task performance was associated with increased activity in the frontal lobe regions, superior parietal lobe and thalamus, and decreased activity in the temporal lobe regions (p < 0.05). Working memory activation (mDSST - cDSST) statistically significantly increased blood flow in the striatum during hypoglycaemia (ETD 0.0374% [95% CI 0.0157, 0.0590], p = 0.002).

CONCLUSIONS/INTERPRETATION

During hypoglycaemia (mean PG 2.9 mmol/l), working memory performance was impaired. Altered performance was associated with significantly increased blood flow in the striatum, a part of the basal ganglia implicated in regulating motor functions, memory, language and emotion.

TRIAL REGISTRATION

NCT01789593, clinicaltrials.gov FUNDING: This study was funded by Novo Nordisk.

Cerebellar Contribution to Pattern Separation of Human Hippocampal Memory Circuits

The cerebellum is a crucial structure for cognitive function as well as motor control. Benign brain tumors such as schwannomas, meningiomas, and epidermoids tend to occur in the cerebellopontine angle cisterns and may cause compression of the posterior lateral cerebellum near the superior posterior fissure, where the eloquent area for cognitive function was recently identified. The present study examined cognitive impairment in patients with benign cerebellar tumors before and after surgical intervention in order to clarify the functional implications of this region in humans. Patients with cerebellar tumors showed deficits in psychomotor speed and working memory compared with healthy controls. Moreover, these impairments were more pronounced in patients with right cerebellar tumors. Functional magnetic resonance imaging during performance of a lure task also demonstrated that cerebellar tumors affected pattern separation or the ability to distinguish similar experiences of episodic memory or events with discrete, non-overlapping representations, which is one of the important cognitive functions related to the hippocampus. The present findings indicate that compression of the human posterior lateral cerebellum affects hippocampal memory function.

Set-Shifting Deficits: A Possible Neurocognitive Endophenotype for Tourette Syndrome Without ADHD

OBJECTIVE

Tourette syndrome (TS) can be associated with cognitive dysfunction. We assessed a range of cognitive abilities in adults with TS without comorbid disorders.

METHOD

Participants completed tests of sustained attention, verbal and non-verbal reasoning, comprehension, verbal fluency, working memory, inhibition, and set-shifting. We compared patients' task performance with that of healthy controls, and evaluated relationships between cognitive abilities and symptoms of obsessive-compulsive disorder (OCD), ADHD, impulse control problems, and mood disorders.

RESULTS

Patients with TS exhibited impairments on four measures assessing response inhibition, fine motor control, set-shifting, and sustained attention. The Wisconsin Card Sorting Test (WCST) discriminated best between patients and controls. Patients' deficits were not correlated with tic severity or symptoms related to OCD, ADHD, or mood disorders.

CONCLUSION

Deficits on the WCST could constitute a neurocognitive endophenotype for TS, reflecting dysfunction within neural networks involving basal ganglia, pre-supplementary motor area, and inferior prefrontal regions.

Protocol for the Reconstructing Consciousness and Cognition (ReCCognition) Study

Important scientific and clinical questions persist about general anesthesia despite the ubiquitous clinical use of anesthetic drugs in humans since their discovery. For example, it is not known how the brain reconstitutes consciousness and cognition after the profound functional perturbation of the anesthetized state, nor has a specific pattern of functional recovery been characterized. To date, there has been a lack of detailed investigation into rates of recovery and the potential orderly return of attention, sensorimotor function, memory, reasoning and logic, abstract thinking, and processing speed. Moreover, whether such neurobehavioral functions display an invariant sequence of return across individuals is similarly unknown. To address these questions, we designed a study of healthy volunteers undergoing general anesthesia with electroencephalography and serial testing of cognitive functions (NCT01911195). The aims of this study are to characterize the temporal patterns of neurobehavioral recovery over the first several hours following termination of a deep inhaled isoflurane general anesthetic and to identify common patterns of cognitive function recovery. Additionally, we will conduct spectral analysis and reconstruct functional networks from electroencephalographic data to identify any neural correlates (e.g., connectivity patterns, graph-theoretical variables) of cognitive recovery after the perturbation of general anesthesia. To accomplish these objectives, we will enroll a total of 60 consenting adults aged 20-40 across the three participating sites. Half of the study subjects will receive general anesthesia slowly titrated to loss of consciousness (LOC) with an intravenous infusion of propofol and thereafter be maintained for 3 h with 1.3 age adjusted minimum alveolar concentration of isoflurane, while the other half of subjects serves as awake controls to gauge effects of repeated neurobehavioral testing, spontaneous fatigue and endogenous rest-activity patterns.

Cognitive decline associated with pathological burden in primary age-related tauopathy

INTRODUCTION

Primary age-related tauopathy (PART) is a neuropathological diagnosis characterized by tau neurofibrillary tangles (NFTs) in the absence of amyloid plaque pathology. Although most individuals over 50 years of age have evidence of NFTs, the clinical and cognitive consequences of PART are not known.

METHODS

We evaluated 226 neuropathologically confirmed PART cases from the National Alzheimer's Coordinating Center database who participated in a total of 846 longitudinal neuropsychological assessments from the Alzheimer's Disease Center program's Uniform Data Set. Mixed-effects statistical models tested whether cognitive decline was associated with Braak stage NFT burden.

RESULTS

Higher stages of NFT burden in PART, with no evidence or minimal evidence of amyloid pathology, were associated with more rapid decline on tasks involving episodic and semantic memory along with tests of processing speed and attention.

DISCUSSION

We conclude that PART has cognitive consequences that should be considered in the context of emerging tau-targeted therapies in age-associated neurodegenerative diseases.

Resting-State Magnetoencephalography Reveals Different Patterns of Aberrant Functional Connectivity in Combat-Related Mild Traumatic Brain Injury

Blast mild traumatic brain injury (mTBI) is a leading cause of sustained impairment in military service members and veterans. However, the mechanism of persistent disability is not fully understood. The present study investigated disturbances in brain functioning in mTBI participants using a source-imaging-based approach to analyze functional connectivity (FC) from resting-state magnetoencephalography (rs-MEG). Study participants included 26 active-duty service members or veterans who had blast mTBI with persistent post-concussive symptoms, and 22 healthy control active-duty service members or veterans. The source time courses from regions of interest (ROIs) were used to compute ROI to whole-brain (ROI-global) FC for different frequency bands using two different measures: 1) time-lagged cross-correlation and 2) phase-lock synchrony. Compared with the controls, blast mTBI participants showed increased ROI-global FC in beta, gamma, and low-frequency bands, but not in the alpha band. Sources of abnormally increased FC included the: 1) prefrontal cortex (right ventromedial prefrontal cortex [vmPFC], right rostral anterior cingulate cortex [rACC]), and left ventrolateral and dorsolateral prefrontal cortex; 2) medial temporal lobe (bilateral parahippocampus, hippocampus, and amygdala); and 3) right putamen and cerebellum. In contrast, the blast mTBI group also showed decreased FC of the right frontal pole. Group differences were highly consistent across the two different FC measures. FC of the left ventrolateral prefrontal cortex correlated with executive functioning and processing speed in mTBI participants. Altogether, our findings of increased and decreased regionalpatterns of FC suggest that disturbances in intrinsic brain connectivity may be the result of multiple mechanisms, and are associated with cognitive sequelae of the injury.

Cognitive impairments in first-episode drug-naive and chronic medicated schizophrenia: MATRICS consensus cognitive battery in a Chinese Han population

Cognitive deficits are a core feature of schizophrenia and we examined the cognitive profile of first-episode and chronic schizophrenia in a Chinese Han population using the MATRICS Consensus Cognitive Battery (MCCB). We recruited 79 first-episode drug-naïve (FEDN) schizophrenia, 132 chronic medicated schizophrenia inpatients and 124 healthy controls. We assessed patient psychopathology using the Positive and Negative Syndrome Scale (PANSS). MCCB total score (p<0.01) and index scores of category fluency, trail making A, digital sequence, Hopkins Verbal Learning Test (HVLT), mazes, and Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) were significantly higher in FEDN than in chronic patients (all p<0.05). FEDN exhibited relative weakness in continuous performance, whereas chronic patients exhibited relative weakness in mazes. Multiple regression analysis confirmed that in FEDN and chronic patients, total score and negative symptom of PANSS were independent contributors to MCCB total score, respectively. Our results not only demonstrate the applicability of the MCCB as a sensitive measure of cognitive impairment for schizophrenia patients in a Chinese Han population, but also suggest that the compromised cognition is present in the early stage of schizophrenia, some of which could be more severe in the chronic stage of illness.

Development and Validation of the Cognition Test Battery for Spaceflight

BACKGROUND

Sustained high-level cognitive performance is of paramount importance for the success of space missions, which involve environmental, physiological, and psychological stressors that may affect brain functions. Despite subjective symptom reports of cognitive fluctuations in spaceflight, the nature of neurobehavioral functioning in space has not been clarified.

METHODS

We developed a computerized cognitive test battery (Cognition) that has sensitivity to multiple cognitive domains and was specifically designed for the high-performing astronaut population. Cognition consists of 15 unique forms of 10 neuropsychological tests that cover a range of cognitive domains, including emotion processing, spatial orientation, and risk decision making. Cognition is based on tests known to engage specific brain regions as evidenced by functional neuroimaging. Here we describe the first normative and acute total sleep deprivation data on the Cognition test battery as well as several efforts underway to establish the validity, sensitivity, feasibility, and acceptability of Cognition.

RESULTS

Practice effects and test-retest variability differed substantially between the 10 Cognition tests, illustrating the importance of normative data that both reflect practice effects and differences in stimulus set difficulty in the population of interest. After one night without sleep, medium to large effect sizes were observed for 3 of the 10 tests addressing vigilant attention (Cohen's d = 1.00), cognitive throughput (d = 0.68), and abstract reasoning (d = 0.65).

CONCLUSIONS

In addition to providing neuroimaging-based novel information on the effects of spaceflight on a range of cognitive functions, Cognition will facilitate comparing the effects of ground-based analogues to spaceflight, increase consistency across projects, and thus enable meta-analyses.

The Relationship between Processing Speed and Regional White Matter Volume in Healthy Young People

Processing speed is considered a key cognitive resource and it has a crucial role in all types of cognitive performance. Some researchers have hypothesised the importance of white matter integrity in the brain for processing speed; however, the relationship at the whole-brain level between white matter volume (WMV) and processing speed relevant to the modality or problem used in the task has never been clearly evaluated in healthy people. In this study, we used various tests of processing speed and Voxel-Based Morphometry (VBM) analyses, it is involves a voxel-wise comparison of the local volume of gray and white, to assess the relationship between processing speed and regional WMV (rWMV). We examined the association between processing speed and WMV in 887 healthy young adults (504 men and 383 women; mean age, 20.7 years, SD, 1.85). We performed three different multiple regression analyses: we evaluated rWMV associated with individual differences in the simple processing speed task, word-colour and colour-word tasks (processing speed tasks with words) and the simple arithmetic task, after adjusting for age and sex. The results showed a positive relationship at the whole-brain level between rWMV and processing speed performance. In contrast, the processing speed performance did not correlate with rWMV in any of the regions examined. Our results support the idea that WMV is associated globally with processing speed performance regardless of the type of processing speed task.

Making cognitive latent variables manifest: distinct neural networks for fluid reasoning and processing speed

Cognitive psychologists posit several specific cognitive abilities that are measured with sets of cognitive tasks. Tasks that purportedly tap a specific underlying cognitive ability are strongly correlated with one another, whereas performances on tasks that tap different cognitive abilities are less strongly correlated. For these reasons, latent variables are often considered optimal for describing individual differences in cognitive abilities. Although latent variables cannot be directly observed, all cognitive tasks representing a specific latent ability should have a common neural underpinning. Here, we show that cognitive tasks representing one ability (i.e., either perceptual speed or fluid reasoning) had a neural activation pattern distinct from that of tasks in the other ability. One hundred six participants between the ages of 20 and 77 years were imaged in an fMRI scanner while performing six cognitive tasks, three representing each cognitive ability. Consistent with prior research, behavioral performance on these six tasks clustered into the two abilities based on their patterns of individual differences and tasks postulated to represent one ability showed higher similarity across individuals than tasks postulated to represent a different ability. This finding was extended in the current report to the spatial resemblance of the task-related activation patterns: The topographic similarity of the mean activation maps for tasks postulated to reflect the same reference ability was higher than for tasks postulated to reflect a different reference ability. Furthermore, for any task pairing, behavioral and topographic similarities of underlying activation patterns are strongly linked. These findings suggest that differences in the strengths of correlations between various cognitive tasks may be because of the degree of overlap in the neural structures that are active when the tasks are being performed. Thus, the latent variable postulated to account for correlations at a behavioral level may reflect topographic similarities in the neural activation across different brain regions.

Associations between birth weight, preeclampsia and cognitive functions in middle-aged adults

Both reductions in birth weight and preeclampsia (PE) have been associated with decrements in scores on tests of intelligence in children and adolescents. We examined whether these decrements persist into middle adulthood and expand into other domains of cognitive functioning. Using data from the Early Determinants of Adult Health project and from the ancillary project, Fetal Antecedents of Major Depression and Cardiovascular Disease, we selected term same-sex sibling sets or singletons from these sets, from the New England Family Study (NEFS) and the Child Health and Development Studies (CHDS), discordant on either fetal growth or PE, to test the hypotheses that prenatal exposure to inflammation was associated with decrements in attention, learning and executive function 40 years later. Exposure was defined as a continuous measure of percentile birth weight for gestational age, reduced fetal growth (<20th percentile of birth weight for gestational age) or maternal PE. Given that the sample was comprised, in part, of sibling sets, the analyses were performed using mixed models to account for the inter-sibling correlations. Analyses were performed separately by study site (i.e. NEFS and CHDS). We found few statistically significant associations (suggesting a possible type II error) consistent with previous literature, suggesting that the associations with low birth weight do not persist into midlife. We discuss the possible reasons for the lack of associations, which include the possible mediating effects of the postnatal environment.

Does neurocognitive function affect cognitive bias toward an emotional stimulus? Association between general attentional ability and attentional bias toward threat

BACKGROUND

Although poorer cognitive performance has been found to be associated with anxiety, it remains unclear whether neurocognitive function affects biased cognitive processing toward emotional information. We investigated whether general cognitive function evaluated with a standard neuropsychological test predicts biased cognition, focusing on attentional bias toward threat.

METHODS

One hundred and five healthy young adults completed a dot-probe task measuring attentional bias and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) measuring general cognitive function, which consists of five domains: immediate memory, visuospatial/constructional, language, attention, and delayed memory. Stepwise multiple regression analysis was performed to examine the relationship between attentional bias and cognitive function.

RESULTS

The attentional domain was the best predictor of attentional bias toward threat (β = -0.26, p = 0.006). Within the attentional domain, digit symbol coding was negatively correlated with attentional bias (r = -0.28, p = 0.005).

CONCLUSIONS

The present study provides the first evidence that general attentional ability, which was assessed with a standard neuropsychological test, affects attentional bias toward threatening information. Individual cognitive profiles might be important for the measurement and modification of cognitive biases.

Effects of VRK2 (rs2312147) on white matter connectivity in patients with schizophrenia

Recent genome-wide association studies of schizophrenia reported a novel risk variant, rs2312147 at vaccinia-related kinase 2 gene (VRK2), in multiple Asian and European samples. However, its effect on the brain structure in schizophrenia is little known. We analyzed the brain structure of 36 schizophrenia patients and 18 healthy subjects with regard to rs2312147 genotype groups. Brain magnetic resonance scans for gray matter (GM) and white matter (WM) analysis, and genotype analysis for VRK2 rs2312147, were conducted. The Positive and Negative Syndrome Scale and the Digit Symbol Test were assessed for schizophrenia patients. There was no significant difference in either GM volume or WM connectivity with regard to rs2312147 genotype in healthy subjects. In contrast, we found significant differences in the WM connectivity between rs2312147 CC and CT/TT genotype groups of schizophrenia patients. The related brain areas included the splenium of corpus callosum, the left occipital lobe WM, the internal capsule (left anterior limb and right retrolenticular part), the bilateral temporal lobe WM, the left fornix/stria terminalis, the left cingulate gyrus WM, and the left parietal lobe WM. Voxelwise correlation analysis revealed that the Digit Symbol Test scores (age corrected) correlated with the fractional anisotropy in WM tracts that previously showed significant group differences between the CT/TT and CC genotypes in the rs2312147 CT/TT genotype group, while no significant correlation was found in the CC genotype group. Our data may provide evidence for the effect of VRK2 on WM connectivity in patients with schizophrenia.

Meta-analysis of functional neuroimaging studies indicates that an increase of cognitive difficulty during executive tasks engages brain regions associated with time perception

OBJECTIVES

We hypothesize that time perception and executive functions are interrelated and share neuroanatomical basis, and that fluctuations in levels of cognitive effort play a role in mediating that relation. The main goal of this study was to identify brain structures activated both by increases in cognitive activity and during time perception tasks.

METHODS

We performed a multimodal meta-analysis to identify common brain regions in the findings of (a) an SDM meta-analysis of neuroimaging studies assessing the brain response to increasing levels of cognitive difficulty, and (b) an ALE meta-analysis on neuroimaging of time perception (Ortuño, Guillén-Grima, López-García, Gómez, & Pla, 2011. Schizophr. Res., 125(2-3), 129-35).

RESULTS AND CONCLUSIONS

Consistent with results of previous, separate meta-analyses, the current study supports the hypothesis that there exists a group of brain regions engaged both in time perception tasks and during tasks requiring cognitive effort. Thus, brain regions associated with working memory and executive functions were found to be engaged during time estimation tasks, and regions associated with time perception were found to be engaged by an increase in the difficulty of non-temporal tasks. The implication is that temporal perception and cognitive processes demanding cognitive control become interlinked when there is an increase in the level of cognitive effort demanded.

Visual system integrity and cognition in early Huntington's disease

Posterior cortical volume changes and abnormal visuomotor performance are present in patients with Huntington's disease (HD). However, it is unclear whether posterior cortical volume loss contributes to abnormal neural activity, and whether activity changes predict cognitive dysfunction. Using magnetic resonance imaging (MRI), we investigated brain structure and visual network activity at rest in patients with early HD (n = 20) and healthy controls (n = 20). The symbol digit modalities test (SDMT) and subtests of the Visual Object and Space Perception Battery were completed offline. For functional MRI data, a group independent component analysis was used. Voxel-based morphometry was employed to assess regional brain atrophy, and 'biological parametric mapping' analyses were included to investigate the impact of atrophy on neural activity. Patients showed significantly worse visuomotor and visual object performance than controls. Structural analyses confirmed occipitotemporal atrophy. In patients and controls, two spatiotemporally distinct visual systems were identified. Patients showed decreased activity in the left fusiform cortex, and increased left cerebellar activity. These findings remained stable after correction for brain atrophy. Lower fusiform cortex activity was associated with lower SDMT performance and with higher disease burden scores. These associations were absent when cerebellar function was related to task performance and disease burden. The results of this study suggest that regionally specific functional abnormalities of the visual system can account for the worse visuomotor cognition in HD patients. However, occipital volume changes cannot sufficiently explain abnormal neural function in these patients.

A comprehensive neuropsychological mapping battery for functional magnetic resonance imaging

Existing batteries for FMRI do not precisely meet the criteria for comprehensive mapping of cognitive functions within minimum data acquisition times using standard scanners and head coils. The goal was to develop a battery of neuropsychological paradigms for FMRI that can also be used in other brain imaging techniques and behavioural research. Participants were 61 healthy, young adult volunteers (48 females and 13 males, mean age: 22.25 ± 3.39 years) from the university community. The battery included 8 paradigms for basic (visual, auditory, sensory-motor, emotional arousal) and complex (language, working memory, inhibition/interference control, learning) cognitive functions. Imaging was performed using standard functional imaging capabilities (1.5-T MR scanner, standard head coil). Structural and functional data series were analysed using Brain Voyager QX2.9 and Statistical Parametric Mapping-8. For basic processes, activation centres for individuals were within a distance of 3-11 mm of the group centres of the target regions and for complex cognitive processes, between 7 mm and 15 mm. Based on fixed-effect and random-effects analyses, the distance between the activation centres was 0-4 mm. There was spatial variability between individual cases; however, as shown by the distances between the centres found with fixed-effect and random-effects analyses, the coordinates for individual cases can be used to represent those of the group. The findings show that the neuropsychological brain mapping battery described here can be used in basic science studies that investigate the relationship of the brain to the mind and also as functional localiser in clinical studies for diagnosis, follow-up and pre-surgical mapping.

Brain training game boosts executive functions, working memory and processing speed in the young adults: a randomized controlled trial

BACKGROUND

Do brain training games work? The beneficial effects of brain training games are expected to transfer to other cognitive functions. Yet in all honesty, beneficial transfer effects of the commercial brain training games in young adults have little scientific basis. Here we investigated the impact of the brain training game (Brain Age) on a wide range of cognitive functions in young adults.

METHODS

We conducted a double-blind (de facto masking) randomized controlled trial using a popular brain training game (Brain Age) and a popular puzzle game (Tetris). Thirty-two volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into eight categories (fluid intelligence, executive function, working memory, short-term memory, attention, processing speed, visual ability, and reading ability).

RESULTS AND DISCUSSION

Our results showed that commercial brain training game improves executive functions, working memory, and processing speed in young adults. Moreover, the popular puzzle game can engender improvement attention and visuo-spatial ability compared to playing the brain training game. The present study showed the scientific evidence which the brain training game had the beneficial effects on cognitive functions (executive functions, working memory and processing speed) in the healthy young adults.

CONCLUSIONS

Our results do not indicate that everyone should play brain training games. However, the commercial brain training game might be a simple and convenient means to improve some cognitive functions. We believe that our findings are highly relevant to applications in educational and clinical fields.

TRIAL REGISTRATION

UMIN Clinical Trial Registry 000005618.

Carnosine treatment for gulf war illness: a randomized controlled trial

About 25% of 1990-1991 Persian Gulf War veterans experience disabling fatigue, widespread pain, and cognitive dysfunction termed Gulf War illness (GWI) or Chronic Multisymptom Illness (CMI). A leading theory proposes that wartime exposures initiated prolonged production of reactive oxygen species (ROS) and central nervous system injury. The endogenous antioxidant L-carnosine (β-alanyl-L-histidine) is a potential treatment since it is a free radical scavenger in nervous tissue. To determine if nutritional supplementation with L-carnosine would significantly improve pain, cognition and fatigue in GWI, a randomized double blind placebo controlled 12 week dose escalation study involving 25 GWI subjects was employed. L-carnosine was given as 500, 1000, and 1500 mg increasing at 4 week intervals. Outcomes included subjective fatigue, pain and psychosocial questionnaires, and instantaneous fatigue and activity levels recorded by ActiWatch Score devices. Cognitive function was evaluated by WAIS-R digit symbol substitution test. Carnosine had 2 potentially beneficial effects: WAIS-R scores increased significantly, and there was a decrease in diarrhea associated with irritable bowel syndrome. No other significant incremental changes were found. Therefore, 12 weeks of carnosine (1500 mg) may have beneficial cognitive effects in GWI. Fatigue, pain, hyperalgesia, activity and other outcomes were resistant to treatment.

Thinking through postoperative cognitive dysfunction: How to bridge the gap between clinical and pre-clinical perspectives

Following surgery, patients may experience cognitive decline, which can seriously reduce quality of life. This postoperative cognitive dysfunction (POCD) is mainly seen in the elderly and is thought to be mediated by surgery-induced inflammatory reactions. Clinical studies tend to define POCD as a persisting, generalised decline in cognition, without specifying which cognitive functions are impaired. Pre-clinical research mainly describes early hippocampal dysfunction as a consequence of surgery-induced neuroinflammation. These different approaches to study POCD impede translation between clinical and pre-clinical research outcomes and may hamper the development of appropriate interventions. This article analyses which cognitive domains deteriorate after surgery and which brain areas might be involved. The most important outcomes are: (1) POCD encompasses a wide range of cognitive impairments; (2) POCD affects larger areas of the brain; and (3) individual variation in the vulnerability of neuronal networks to neuroinflammatory mechanisms may determine if and how POCD manifests itself. We argue that, for pre-clinical and clinical research of POCD to advance, the effects of surgery on various cognitive functions and brain areas should be studied. Moreover, in addition to general characteristics, research should take inter-relationships between cognitive complaints and physical and mental characteristics into account.

Experimental strategy for translational studies of organophosphorus pesticide neurotoxicity based on real-world occupational exposures to chlorpyrifos

Translational research is needed to understand and predict the neurotoxic consequences associated with repeated occupational exposures to organophosphorus pesticides (OPs). In this report, we describe a research strategy for identifying biomarkers of OP neurotoxicity, and we characterize pesticide application workers in Egypt's Menoufia Governorate who serve as our anchor human population for developing a parallel animal model with similar exposures and behavioral deficits and for examining the influence of human polymorphisms in cytochrome P450 (CYP) and paraoxonase 1 (PON1) enzymes on OP metabolism and toxicity. This population has previously been shown to have high occupational exposures and to exhibit a broad range of neurobehavioral deficits. In addition to observational studies of work practices in the field, questionnaires on demographics, lifestyle and work practices were administered to 146 Egyptian pesticide application workers applying pesticides to the cotton crop. Survey results indicated that the application workforce uses standard operating procedures and standardized equipment provided by Egypt's Ministry of Agriculture, which provides a workforce with a stable work history. We also found that few workers report using personal protective equipment (PPE), which likely contributes to the relatively high exposures reported in these application workers. In summary, this population provides a unique opportunity for identifying biomarkers of OP-induced neurotoxicity associated with occupational exposure.

The effect of regular walks on various health aspects in older people with dementia: protocol of a randomized-controlled trial

BACKGROUND

Physical activity has proven to be beneficial for physical functioning, cognition, depression, anxiety, rest-activity rhythm, quality of life (QoL), activities of daily living (ADL) and pain in older people. The aim of this study is to investigate the effect of walking regularly on physical functioning, the progressive cognitive decline, level of depression, anxiety, rest-activity rhythm, QoL, ADL and pain in older people with dementia.

METHODS/DESIGN

This study is a longitudinal randomized controlled, single blind study. Ambulatory older people with dementia, who are regular visitors of daily care or living in a home for the elderly or nursing home in the Netherlands, will be randomly allocated to the experimental or control condition. Participants of the experimental group make supervised walks of 30 minutes a day, 5 days a week, as part of their daily nursing care. Participants of the control group will come together three times a week for tea or other sedentary activities to control for possible positive effects of social interaction. All dependent variables will be assessed at baseline and after 6 weeks, and 3, 6, 9, 12 and 18 months of intervention. The dependent variables include neuropsychological tests to assess cognition, physical tests to determine physical functioning, questionnaires to assess ADL, QoL, level of depression and anxiety, actigraphy to assess rest-activity rhythm and pain scales to determine pain levels. Potential moderating variables at baseline are: socio-demographic characteristics, body mass index, subtype of dementia, apolipoprotein E (ApoE) genotype, medication use and comorbidities.

DISCUSSION

This study evaluates the effect of regular walking as a treatment for older people with dementia. The strength of this study is that 1) it has a longitudinal design with multiple repeated measurements, 2) we assess many different health aspects, 3) the intervention is not performed by research staff, but by nursing staff which enables it to become a routine in usual care. Possible limitations of the study are that 1) only active minded institutions are willing to participate creating a selection bias, 2) the drop-out rate will be high in this population, 3) not all participants will be able to perform/understand all tests.

TRIAL REGISTRATION

NTR1482.