Executive function predictors of delayed memory deficits after mild traumatic brain injury

Delayed memory deficits are common for patients with mild traumatic brain injury (mTBI), according to a recent systematic review of meta-analyses (Karr et al., 2014). However, there has been little work to identify different cognitive processes that may be underpinning these delayed memory deficits for mTBI. Frontal cortex is important for delayed memory, and is implicated in the pathophysiology of mTBI; moreover, frontal lobes are typically considered the locus of executive abilities. To further explore these relationships, we sought to partly explain delayed memory deficits after mTBI by examining behavioral indicators of executive function. Results showed that sub-acute as well as chronic mTBI patients performed worse than controls on the delayed memory trial of the Hopkins Verbal Learning Test-Revised (Brandt & Benedict, 2001), recalling approximately 18% and 15% fewer words, respectively. Furthermore, worse delayed memory performance was associated with less use of the cognitive strategy of semantic clustering, and with lower scores for the executive function composite from a standardized neuropsychological battery (NIH EXAMINER; Kramer et al., 2014). In contrast, serial clustering, a memory organizational strategy thought to be less dependent on executive function, did not show strong relationships to clinical status or delayed memory performance. This exploratory work suggests novel hypotheses to be tested in future, confirmatory studies, including that general executive functions and/or semantic clustering will mediate delayed memory deficits following mTBI.

Neuropsychological assessment and cortisol levels in biofluids from early Alzheimer's disease patients

Cortisol dysregulation is proposed as a factor in the development of Alzheimer's disease (AD). AD patients can show high cortisol levels in prodromal phases of AD, early enough that neuropsychological alterations exist but activities of daily living remain unimpaired. Nevertheless, it is unknown if biofluid cortisol levels can have some AD predictive power together with neuropsychological assessment in prodromal stages in comparison with other cognitive disorders. In this work, an analytical method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was applied to determine the cortisol levels in different biofluids (urine, plasma, saliva, cerebrospinal fluid). Early AD patients and non-AD patients recruited at out-patient neurological unit were classified from the standard cerebrospinal fluid biomarkers levels (β-amyloid, tau, phosphorylated tau), and studied with an extensive neuropsychological assessment including global, neuropsychological, functional and affective scales. We used a logistic regression model to discriminate between the AD and non-AD groups. Higher plasma cortisol levels were found in the AD group than in the non-AD group (p < 0.001). Regarding neuropsychological evaluation, delayed memory was used as representative of the neuropsychological status, and lower scores were obtained in the AD group (p < 0.001). The prediction model, including plasma cortisol levels and delayed memory scores, achieved an AUC of 0.93, as well as a sensitivity of 97% and a specificity of 69.4%. In conclusion, plasma cortisol levels and delayed memory scores were specifically impaired in early AD, allowing the development of a new diagnostic model which could be employed as a very satisfactory screening system.

Altered brain activity in the bilateral frontal cortices and neural correlation with cognitive impairment in schizophrenia

Cognitive impairments are core aspects of schizophrenia and are highly related to poor outcomes. However, the effect of therapy on cognitive impairments remains unsatisfactory as its biological mechanisms are not fully understood. The purpose of this study was to investigate the disrupted intrinsic neural activity of the frontal areas and to further examine the functional connectivity of frontal areas related to cognitive impairments in schizophrenia. We collected brain imaging data using a 3T Siemens Prisma MRI system in 32 patients with schizophrenia and 34 age- and sex-matched healthy controls. The mean fractional amplitude of low-frequency fluctuation (mfALFF) in the frontal regions was calculated and analyzed to evaluate regional neural activity alterations in schizophrenia. Seed regions were generated from clusters showing significant changes in mfALFF in schizophrenia, and its resting-state functional connectivity (rs-FC) with other brain regions were estimated to detect possible aberrant rs-FC indicating cognitive impairments in schizophrenia. We found that mfALFF in the bilateral frontal cortices was increased in schizophrenia. mfALFF-based rs-FC revealed that decreased rs-FC between left middle frontal gyrus (MFG) and left medial superior frontal gyrus (MFSG) was associated with poor delayed memory (r = 0.566, Bonferroni-corrected p = 0.012). These findings demonstrate increased neural activity in the frontal cortices in schizophrenia. FC analysis revealed a diminished rs-FC pattern between the left MFG and left MSFG that was associated with cognitive impairments. These findings have provided deeper insight into the alterations in brain function related to specific domains of cognitive impairment and may provide evidence for precise interventions for cognitive deficits in schizophrenia.

[Effect of Moxibustion on Delayed Memory and Expression of Hippocampal Nestin and Doublecortin Proteins in Dementia Rats]

OBJECTIVE

To observe the effect of "Huayu Tongluo"(Blood-stasis Dispersing and Meridian-collateral Dredging) moxibustion on the delayed memory and expression of Nestin and Doublecortin (DCX) proteins in the hippocampus in vascular dementia (VD) rats in the view of neurogenesis produced by intracerebral transplantation of neural stem cells (NSCs) and endothelial progenitor cells (EPCs).

METHODS

Healthy male Wistar rats were randomized into control group, VD model group,NSCs＋EPCs group and NSCs＋EPCs moxibustion group. The VD model was established by using a modified 2-vessels occlusion method, and neurogenesis was produced by transplantation of NSCs＋EPCs (2×10⁶cell/10 µL) into the lateral ventricle for rats of the NSCs＋EPCs groups 3 days after successful VD-modeling. Moxibustion was applied to "Dazhui" (GV 14), "Baihui" (GV 20) and "Shenting" (GV 24) once daily for 21 days with an interval of one day between every two 7 days. The Morris Water Maze was used to test the rat's delayed memory ability before and 24 h after the treatment. The expression of Nestin and DCX proteins in the hippocampus tissues was detected using double-labeled immunofluorescence technique.

RESULTS

Following modeling, Morris Water Maze tests showed that the average escape latency of location navigation task was significantly prolonged in VD rats(P<0.008)and the times of target platform crossing (spatial probing task) within 120 s were remarkably reduced in VD rats (P<0.008). Compared with pre-treatment in the same one group, the escape latency of NSCs＋EPCs and NSCs＋EPCs moxibustion groups were considerably reduced (P<0.05), and the average times of target platform crossing of the NSCs＋EPCs moxibustion group were markedly increased(P<0.05). The effect of NSCs＋EPCs moxibustion was evidently superior to that of simple NSCs＋EPCs in shortening the escape latency (P<0.008). The expression levels of Nestin protein were significantly higher in the NSCs＋EPCs moxibustion group after 1 and 3 period treatment than those in the NSCs＋EPCs group (P<0.05)．.

CONCLUSION

Moxibustion intervention is able to improve the delayed memory in VD rats, which may be related to its effect in up-regulating the expression of hippocampal Nestin and DCX proteins within 15 days via accelerating neurogenesis.

Understanding relational binding in early childhood: Interacting effects of overlap and delay

Episodic memories typically share overlapping elements in distinctive combinations, and to be valuable for future behavior they need to withstand delays. There is relatively little work on whether children have special difficulty with overlap or withstanding delay. However, Yim, Dennis, and Sloutsky (Psychological Science, 2013, Vol. 24, pp. 2163-2172) suggested that extensive overlap is more problematic for younger children, and Darby and Sloutsky (Psychological Science, 2015, Vol. 26, pp. 1937-1946) reported that a 48-h delay period actually improves children's memory for overlapping pairs of items. In the current study, we asked how children's episodic memory is affected by stimulus overlap, delay, and age using visual stimuli containing either overlapping or unique item pairs. Children aged 4 and 6 years were tested both immediately and after a 24-h delay. As expected, older children performed better than younger children, and both age groups performed worse on overlapping pairs. Surprisingly, the 24-h delay had only a marginal effect on overall accuracy. Although there were no interactions, when errors were examined, there was evidence that delay buffered memory for overlapping pairs against cross-contextual confusion for younger children.

Physiological and Cognitive Determinants of Gait Variability of Asian Population: The Yishun Study

INTRODUCTION

Gait variability is associated with frailty, dementia, and falls. Studies on the association of physiological and cognitive factors with gait variability have seldom included middle-aged adults, even though these adults already experienced loss of muscular strength and postural stability. This study aimed a) to examine and compare the trend of gait variability in men and women, across the adult age spectrum, and b) to identify and compare the contributions of physiological and cognitive factors to gait variability.

METHODS

This was a population-based cross-sectional study at a single center. A random sample of 507 community-dwelling, well-functioning adults aged 21-90 years were studied. Cognition was measured using the Repeatable Battery for the Assessment of Neuropsychological Status. Physiological factors examined included visual contrast sensitivity (VCS), postural sway, hand reaction time, handgrip strength (HGS), knee extensor strength, and gait variability (coefficient of variation [CoV]). Multivariable regression models were used to examine the association between physiological and cognitive performance with gait CoV.

RESULTS

Women walked with greater stride width CoV (p < 0.01) and double support time (DST) CoV (p < 0.01) than men. The stride width (p = 0.01) and DST variability (p = 0.03) were significantly higher in older men as compared to men in younger age-groups. Gait speed accounted for most of the gait CoV variances and attenuated the effects of physiological performance and/or attention cognition on most gait variability, except for CoV of DST and stride width. Adults with better VCS (β = -0.19), faster hand reaction (β = 0.12), and greater HGS (β = -0.15) had lower variability in step length.

CONCLUSION

The trends of stride width CoV and DST CoV across adult age spectrum were different between men and women. Greater stride width variability was partly attributed to greater HGS, possibly to better control lateral stability during walking. Physiological factors outweigh cognition in regulating most of the gait CoV in this study. They are modifiable and potential targets for healthy aging program.

Influence of social activities on delayed memory in older adults: A cross-cultural study

This study investigated the impact of social activities on delayed memory among older adults, framed within Social Support Theory and Social Gerontology. By comparing Chinese and American populations, we aim to fill a gap in the cross-cultural research on this topic. Using data from the China Health and Retirement Longitudinal Study and the U.S. Health and Retirement Study, we employed quantitative analysis with Stata 18.0. We discovered that social activities like internet use, card games, and volunteer work significantly enhance delayed memory across both cultures. However, cultural differences influence the types of social activities that are more prevalent in each context and affect the degree of their impact on cognitive health. In China, card games had a stronger effect on delayed memory, while in the United States, volunteer work and internet use exerted a more pronounced impact. These findings highlight the importance of culturally tailored interventions and the combined role of family and community support systems in promoting cognitive health among older adults.

Independent and interactive effect of type 2 diabetes and hypertension on memory functions in middle aged adults

BACKGROUND

The study distinguishes the effect of type 2 diabetes and hypertension on cognitive functions when the two diseases are alone or when they occur together, compared to healthy individuals.

METHODS

A total of 143 middle-aged adults were screened using the Wechsler Memory Scale - Revised psychometric test (verbal memory, visual memory, attention/concentration and delayed memory). Participants were divided into four groups based on their diseases: patients with type 2 diabetes (36), patients with hypertension (30), patients having both diseases (33), and healthy controls (44).

RESULTS

This study found no differences among investigated groups in verbal and visual memory, however, hypertension and both-disease group performed unfavorably compared to patients with diabetes and to healthy individuals in attention/concentration and delayed memory.

CONCLUSIONS

The findings of this study suggest that there is a relationship between hypertension and cognitive dysfunction, whereas type 2 diabetes without consequences was not proved to have an association with cognitive decline in middle-aged people.

Choline kinase alpha genotype is related to hippocampal brain volume and cognition in postmenopausal women

This study examined how single nucleotide polymorphisms (SNPs) related to choline synthesis and metabolism, processes largely regulated by estrogen, influenced hippocampal volume and neuropsychological function following menopause. We investigated the effect of choline kinase alpha (CHKA) genotype on brain volume and neuropsychological performance in postmenopausal women. The effect alleles of certain CHKA SNPs (rs6591331 T, rs10791957 A) are associated with varied responses to choline deficiency and delegation of choline to physiological pathways. The presence of these alleles was hypothesized to correlate with worse cognitive performance in women after menopause. Results from structural MRI scans revealed larger right hippocampal volumes in subjects with a T/T CHKA rs6591331 genotype compared to A/A subjects. Delayed memory scores from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) were lower in subjects with T/T genotypes compared to those with the A/T genotype and the A/A genotype. Based on these findings, we proposed a CHKA-dependent mechanism present within the brain to compensate for the decreased estrogen and biosynthesized choline associated with menopause.

Association between the HHEX polymorphism and delayed memory in first-episode schizophrenic patients

The hematopoietically-expressed homeobox gene (HHEX) played a critical role in regulating the immune system that the abnormality of which was involved in the psychopathology and cognitive deficits of psychiatric disorders. The aim of this study was to investigate the effect of HHEX rs1111875 polymorphism on the susceptibility and cognitive deficits of first-episode schizophrenic patients (FSP). We assessed cognitive function in 239 first-episode patients meeting DSM-IV for schizophrenia, and 368 healthy controls using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The HHEX rs1111875 polymorphism was genotyped. Our results showed that the allelic and genotypic frequencies of HHEX rs1111875 polymorphism didn't differ between FSP and healthy controls (both p > 0.05) after adjusting for sex and age. Cognitive test scores in FSP were significantly lower than those in healthy controls on all scales (all p < 0.001) except for the visuospatial/constructional score (p > 0.05) after adjusting for covariates. There was a significant genotype (p < 0.05) rather than genotype × diagnosis (p > 0.05) effect on the delayed memory score after adjusting for covariates. The HHEX rs1111875 polymorphism was significantly associated with the delayed memory score in FSP (p < 0.05), but not in healthy controls (p > 0.05) after adjusting for covariates. Our findings supported that the HHEX rs1111875 polymorphism did not contribute to the susceptibility to FSP. However, this polymorphism might influence the delayed memory in FSP. Moreover, FSP had poorer cognitive function than healthy controls except for the visuospatial/constructional domain.