Vulnerability of the frontal and parietal regions in hypertensive patients during working memory task

Hypertension Impacts the Oscillatory Dynamics Serving the Encoding Phase of Verbal Working Memory

BACKGROUND

Chronic hypertension is known to be a major contributor to cognitive decline, with executive function and working memory being among the domains most commonly affected. Despite the growing literature on such dysfunction in patients with hypertension, the underlying neural processes are poorly understood.

METHODS

In this cross-sectional study, we examine these neural processes by having participants with controlled hypertension, uncontrolled hypertension, and healthy controls perform a verbal working memory task during magnetoencephalography. Neural oscillations associated with the encoding and maintenance components of the working memory task were imaged and statistically evaluated among the 3 groups.

RESULTS

Differences related to hypertension emerged during the encoding phase, where the hypertension groups exhibited weaker α-β oscillatory responses compared with controls in the left parietal cortices, whereas such oscillatory activity differed between the 2 hypertension groups in the right prefrontal regions. Importantly, these neural responses in the prefrontal and parietal cortices during encoding were also significantly associated with behavioral performance across all participants.

CONCLUSIONS

Overall, our data suggest that hypertension is associated with neurophysiological abnormalities during working memory encoding, whereas the neural processes serving maintenance seem to be preserved. The right hemispheric neural responses likely reflected compensatory processing, which patients with controlled hypertension may use to achieve verbal working memory function at the level of controls, as opposed to the uncontrolled hypertension group where diminished resources may have limited such additional recruitment.

Effects of exergame and bicycle exercise intervention on blood pressure and executive function in older adults with hypertension: A three-group randomized controlled study

Management of hypertension and prevention of cognitive decline are challenging public health problems. However, the effects of exergame intervention on blood pressure (BP) remain to be explored, and whether exergame intervention is an effective alternative to traditional physical exercise intervention for older adults with hypertension remains to be demonstrated. This study aimed to explore the effectiveness of moderate-intensity exergame intervention and bicycle exercise training on BP and executive function in older hypertensive patients. A total of 128 participants were randomly assigned to the exergame intervention group (n = 41), bicycle exercise intervention group (n = 44), and control group (n = 43). The intervention groups exercised for 60 min, 3 times per week, for 16 weeks, while the control group maintained their normal lifestyle. The results revealed that there were no significant differences between two intervention groups and control group in systolic BP and diastolic BP changes (ps > 0.05). Both intervention groups demonstrated significant improvements in working memory when compared with control group (exergame intervention group: -461.9 ms, p = 0.025; bicycle exercise intervention group: -470.1 ms, p = 0.021). There were no significant differences in systolic BP, diastolic BP, or working memory between the two intervention groups after 16 weeks of training (ps > 0.05). No difference in inhibition or cognitive flexibility was observed between the intervention and control groups (ps > 0.05). The current results showed that moderate-intensity exergame intervention did not produce significant benefits in reducing BP, but yielded similar beneficial effects in working memory to that of bicycle exercise intervention. More studies are needed on whether exergame intervention has the potential to be a promising supplemental therapeutic tool for older adults with hypertension.

Effects of hypertension and aging on brain function in spontaneously hypertensive rats: a longitudinal resting-state functional magnetic resonance imaging study

To investigate the dynamic evolution of brain function under the comorbidities of hypertension and aging. Resting-state functional magnetic resonance imaging scans were longitudinally acquired at 10, 24, and 52 weeks in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats. We computed the mean amplitude of low-frequency fluctuation (mALFF), mean regional homogeneity (mReHo), and functional connectivity (FC). There was no interaction between hypertension and aging on brain function. The main effect of aging reflects primarily the cumulative increase of brain activity, especially the increase of mALFF in amygdala and mReHo in cingulate cortex, accompanied by the decrease of brain activity. The main effect of hypertension reflects primarily decreased brain activity in default modal network, accompanied by increased brain activity. The main effect of aging shows reduced brain FC as early as 24 weeks, and the main effect of hypertension shows higher brain FC in SHRs. The novel discovery is that 1 brain FC network increased linearly with age in SHRs, in addition to the linearly decreasing FC. Hypertension and aging independently contribute to spatiotemporal alterations in brain function in SHRs following ongoing progression and compensation. This study provides new insight into the dynamic characteristics of brain function.

Cerebral blood flow network differences correlated with cognitive impairment in mild traumatic brain injury

Purpose

To examine whether the cerebral blood flow (CBF) and CBF connectivity differences are sex-specific and whether these differences are correlated with cognitive impairment in mTBI.

Methods

Resting-state perfusion magnetic resonance imaging was performed in 40 patients with acute mTBI and 40 healthy controls by using pseudocontinuous arterial spin labeling within 14 days following injury. The differences in normalized CBF were first compared and CBF connectivity of the brain regions with significant CBF differences were compared next. The association between the normalized CBF and CBF connectivity differences and cognitive function were further investigated.

Results

Men patients had lower normalized CBF in the frontal gyrus, temporal gyrus and hippocampus and decreased negative CBF connectivity between brain regions including the hippocampus, temporal gyrus, postcentral gyrus and lenticular nucleus, putamen, compared with men controls. Women patients had lower normalized CBF in the frontal gyrus, however had higher normalized CBF in the temporal gyrus and hippocampus, compared with women controls. Additionally, women patients showed increased positive CBF connectivity between the seed region of interest (ROI) of the right inferior temporal gyrus and temporal gyrus and frontal gyrus, and had increased positive CBF connectivity between the seed ROI of the right hippocampus and the temporal gyrus. Furthermore, men patients had higher CBF in the right middle temporal gyrus and left precentral gyrus than women patients.

Conclusion

This study provides evidence of sex differences in both decreased and increased CBF and CBF connectivity and association with cognitive outcome in the acute stage after mTBI.

The Effect of APOE ɛ4 on the Functional Connectivity in Frontoparietal Network in Hypertensive Patients

Allele 4 of the apolipoprotein E gene (APOE ε4) and hypertension are considered risk factors for Alzheimer’s Disease (AD). The detection of differences in cognitive function and brain networks between hypertensive patients who are APOE ε4 carriers and non-carriers may help in understanding how hypertension and risk genes cumulatively impair brain function, which could provide critical insights into the genetic mechanism by which hypertension serves as a potential risk factor for cognitive decline and even AD. Using behavioral data from 233 elderly hypertensive patients and neuroimaging data from 38 of them from Beijing, China; the study aimed to assess the effects of APOE ε4 on cognition and to explore related changes in functional connectivity. Cognitively, the patients with APOE ε4 showed decreased executive function, memory and language. In the MRI sub-cohort, the frontoparietal networks in the APOE ε4 carrier group exhibited an altered pattern, mainly in the left precentral regions, inferior frontal lobe and angular gyrus. More importantly, the decline of cognitive function was correlated with abnormal FC in the left precentral regions in APOE ε4 carriers. APOE ε4 aggravated the dysfunction in frontal and parietal regions in hypertensive patients. This highlights the importance of brain protection in hypertensive patients, especially those with a genetic risk of AD.

Early prevention of cognitive impairment in the community population: The Beijing Aging Brain Rejuvenation Initiative

Facing considerable challenges associated with aging and dementia, China urgently needs an evidence-based health-care system for prevention and management of dementia. The Beijing Aging Brain Rejuvenation Initiative (BABRI) is a community-based cohort study initiated in 2008 that focuses on asymptomatic stages of dementia, aims to develop community-based prevention strategies for cognitive impairment, and provides a platform for scientific research and clinical trials. Thus far, BABRI has recruited 10,255 participants (aged 50 and over, 60.3% female), 2021 of whom have been followed up at least once at a 2- or 3-year interval. This article presents aims and study design of BABRI; summarizes preliminary behavioral and neuroimaging findings on mild cognitive impairment (MCI) and results of clinical trials on MCI; and discusses issues concerning early prevention in community, MCI diagnosis methods, and applications of database of aging and dementia. BABRI is proposed to build a systematic framework on brain health in old age.

Altered amplitude of low-frequency fluctuations and default mode network connectivity in high myopia: a resting-state fMRI study

AIM

To analyze changes in amplitude of low-frequency fluctuations (ALFFs) and default mode network (DMN) connectivity in the brain, using resting-state functional magnetic resonance imaging (rs-fMRI), in high myopia (HM) patients.

METHODS

Eleven patients with HM (HM group) and 15 age- and sex-matched non-HM controls (non-HM group) were recruited. ALFFs were calculated and compared between HM group and non-HM group. Independent component analysis (ICA) was conducted to identify DMN, and comparisons between DMNs of two groups were performed. Region-of-interest (ROI)-based analysis was performed to explore functional connectivity (FC) between DMN regions.

RESULTS

Significantly increased ALFFs in left inferior temporal gyrus (ITG), bilateral rectus gyrus (REC), bilateral middle temporal gyrus (MTG), left superior temporal gyrus (STG), and left angular gyrus (ANG) were detected in HM group compared with non-HM group (all P<0.01). HM group showed increased FC in the posterior cingulate gyrus (PCC)/precuneus (preCUN) and decreased FC in the left medial prefrontal cortex (mPFG) within DMN compared with non-HM group (all P<0.01). Compared with non-HM group, HM group showed higher FC between mPFG and bilateral middle frontal gyrus (MFG), ANG, and MTG (all P<0.01). In addition, HM patients showed higher FC between PCC/(preCUN) and the right cerebellum, superior frontal gyrus (SFG), left preCUN, superior frontal gyrus (SFG), and medial orbital of the superior frontal gyrus (ORB supmed; all P<0.01).

CONCLUSION

HM patients show different ALFFs and DMNs compared with non-HM subjects, which may imply the cognitive alterations related to HM.

Altered functional connectivity of brain regions based on a meta-analysis in patients with T2DM: A resting-state fMRI study

OBJECTIVE

To explore the neural mechanisms of brain impairment in type 2 diabetes mellitus (T2DM), abnormal changes to the functional connections between brain regions in the resting state were investigated based on a meta-analysis.

METHODS

Resting-state functional magnetic resonance imaging (fMRI) and neuropsychological assessment were performed on 38 patients with T2DM and 33 healthy controls (HCs). Functional connectivity between regions based on a meta-analysis and other voxels in the brain was calculated and compared between the two groups using a two-sample t test. A correlation analysis was conducted between clinical/cognitive variables and functional connection values from the regions with significant differences in the above comparison.

RESULTS

Patients in the T2DM group showed a significantly decreased functional connection between the right posterior cerebellum and the right middle/inferior occipital gyrus, left middle temporal gyrus, left superior frontal gyrus, left middle frontal gyrus, left insula, left precuneus, and right paracentral lobule/left precuneus when compared with HC group. The functional connection values between the right insula and left medial frontal gyrus, left supplementary motor area, and between the left lingual gyrus and right middle/inferior occipital gyrus in patients with T2DM were significantly decreased. Moreover, the functional connection values between the right posterior cerebellum and left middle frontal gyrus, and between the right posterior cerebellum and left precuneus were negatively correlated with HbA1c in the T2DM group (r = -.356, p = .03; r = -.334, p = .043).

CONCLUSIONS

Our study showed a wide range of cerebellar-cerebral circuit abnormalities in patients with T2DM, which provides a new direction to investigate the neuropathological mechanisms of T2DM from the perspective of the cerebellum.

Abnormal Neural Activity in Children With Diffuse Intrinsic Pontine Glioma Had Manifested Deficit in Behavioral Inhibition: A Resting-State Functional MRI Study

PURPOSE

The purpose of this study was to investigate whether alterations of regional neural function in children with diffuse intrinsic pontine glioma (DIPG) had manifested deficit in behavioral inhibition using resting-state functional MRI (rs-fMRI).

METHODS

There were 17 participants with DIPG who took part in the study. Eight children were with deficit in behavioral inhibition, whereas the other 9 children did not obtain deficit in behavioral inhibition. Five healthy children with age, sex, and education matched to the study group also participated as the control group. These 3 groups underwent rs-fMRI, and the results were then converted to amplitude of low-frequency fluctuation (ALFF) data. Amplitude of low-frequency fluctuation data were further analyzed by single-factor analysis of variance comparing among 3 groups based on the whole brain levels. Amplitude of low-frequency fluctuation results were subjected to t test of voxel-wised comparison to derive the rs-fMRI brain function differences between the 2 DIPG groups. The Pearson correlation between ALFF values of abnormal regions found in 3 groups and the scores obtained according to the Child Behavior Checklist were analyzed.

RESULTS

The 3 groups had shown significant differences in terms of the ALFF results, with the ALFF increased in several brain regions (P < 0.05, corrected with AlphaSim, clusters >59 voxels), which include left supramarginal gyrus, left dorsolateral superior frontal gyrus, right precentral gyrus, and right middle frontal gyrus. Participants with deficit in behavioral inhibition had shown significant differences (ALFF decreased) in several brain regions, including left dorsolateral superior frontal gyrus and right fusiform gyrus (P < 0.05, corrected with AlphaSim, clusters >123 voxels), whereas other brain regions had shown ALFF increased, including left supramarginal gyrus, left middle frontal gyrus, and right medial superior frontal gyrus (P < 0.05, corrected with AlphaSim, clusters >123 voxels). There was no significant correlation between ALFF values and Child Behavior Checklist scores (P > 0.05).

CONCLUSIONS

These findings of focal spontaneous hyperfunction and hypofunction, which correlate with deficit in behavioral inhibition processing, and the abnormal brain regions are considered to be inefficient (in regions of the brain that may relate to compensatory brain and behavioral functioning, and it may be that the brain region needs to exert extra energy to perform a task to the same degree as the control group) or inability (inability in a certain region, or underpowered), pointing to a pathophysiologic process in executive dysfunction.

Effects of Acute Aerobic Exercise on Cognition and Constructs of Decision-Making in Adults With and Without Hypertension

Hypertension accelerates brain aging, resulting in cognitive dysfunction with advancing age. Exercise is widely recommended for adults with hypertension to attenuate cognitive dysfunction. Whether acute exercise benefits cognitive function in this at-risk population is unknown. The purpose of this study was to compare the effects of acute aerobic exercise on cognitive function in 30 middle-aged hypertensive (HTN) and 30 age, sex, and body mass index (BMI)-matched non-HTN adults (56 ± 6 years, BMI 28.2 ± 2.9 kg/m²; 32 men). Subjects underwent cognitive testing pre/post 30-min cycling (≈55% peak oxygen consumption). Cognition was assessed using standard metrics of accuracy and reaction time (RT) across memory recognition, 2-back, and Flanker tasks. Behavioral data was further analyzed using drift-diffusion modeling to examine underlying components of decision-making (strength of evidence, caution, bias) and RT (non-decision time). Exercise elicited similar changes in cognitive function in both HTN and non-HTN groups (p > 0.05). Accuracy was unaltered for Flanker and 2-back tasks, while hits and false alarms increased for memory recognition post-exercise (p < 0.05). Modeling results indicated changes in memory hits/false alarms were due to significant changes in stimulus bias post-exercise. RT decreased for Flanker and memory recognition tasks and was driven by reductions in post-exercise non-decision time (p < 0.05). Our data indicate acute exercise resulted in similar, beneficial cognitive responses in both middle-age HTN and non-HTN adults, marked by unaltered task accuracy, and accelerated RT post-exercise. Additionally, drift-diffusion modeling revealed that beneficial acceleration of cognitive processing post-exercise (RT) is driven by changes in non-decision components (encoding/motor response) rather than the decision-making process itself.