Aberrant frontostriatal connectivity in Alzheimer's disease with positive palmomental reflex

Primitive reflexes and dementia in older adults: a meta-analysis of observational and cohort studies

Primitive reflexes (PRs) are clinical signs that indicate diffuse cerebral dysfunction and frontal lesions. We aimed to present a comprehensive analysis of the prevalence and risk of PRs in patients with dementia. English-language articles published from January 1990 to April 2021 were searched in PubMed, ScienceDirect, Cochrane, and Web of Science with keywords. The titles and abstracts of the identified articles were screened to identify potentially relevant papers. Odds ratios and risk ratios were extracted with 95% confidence intervals and combined using the random-effects model after logarithmic transformation. The prevalence in dementia patients was also combined using the random-effects model. This meta-analysis involved 29 studies. The snout reflex (48% of cases) was the most prevalent. It was found that the risk of PRs in individuals with dementia was significantly elevated, ranging from 13.94 to 16.38 times higher than in healthy controls. The grasp reflex exhibited the highest risk for dementia. This meta-analysis showed that the prevalence and the risk of PRs is high in older patients with dementia. Therefore, PRs, especially the grasp reflex, should be carefully assessed as a part of routine physical examination in the diagnostic process for dementia.

Abnormal functional connectivity of the frontostriatal circuits in type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with an increased incidence of cognitive and emotional disorders. Previous studies have indicated that the frontostriatal circuits play a significant role in brain disorders. However, few studies have investigated functional connectivity (FC) abnormalities in the frontostriatal circuits in T2DM.

Objective

We aimed to investigate the abnormal functional connectivity (FC) of the frontostriatal circuits in patients with T2DM and to explore the relationship between abnormal FC and diabetes-related variables.

Methods

Twenty-seven patients with T2DM were selected as the patient group, and 27 healthy peoples were selected as the healthy controls (HCs). The two groups were matched for age and sex. In addition, all subjects underwent resting-state functional magnetic resonance imaging (rs-fMRI) and neuropsychological evaluation. Seed-based FC analyses were performed by placing six bilateral pairs of seeds within a priori defined subdivisions of the striatum. The functional connection strength of subdivisions of the striatum was compared between the two groups and correlated with each clinical variable.

Results

Patients with T2DM showed abnormalities in the FC of the frontostriatal circuits. Our findings show significantly reduced FC between the right caudate nucleus and left precentral gyrus (LPCG) in the patients with T2DM compared to the HCs. The FC between the prefrontal cortex (left inferior frontal gyrus, left frontal pole, right frontal pole, and right middle frontal gyrus) and the right caudate nucleus has a significant positive correlation with fasting blood glucose (FBG).

Conclusion

The results showed abnormal FC of the frontostriatal circuits in T2DM patients, which might provide a new direction to investigate the neuropathological mechanisms of T2DM.

Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders

We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to a developmental asynchrony and an unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.

Distinct profiles of functional connectivity density aberrance in Alzheimer's disease and mild cognitive impairment

INTRODUCTION

Investigating the neuroimaging changes from mild cognitive impairment (MCI) to Alzheimer's disease (AD) is of great significance. However, the details about the distinct functional characteristics of AD and MCI remain unknown.

METHODS

In this study, we investigated distinct profiles of functional connectivity density (FCD) differences between AD and MCI compared with the normal population, aiming to depict the progressive brain changes from MCI to AD. As a data-driven method, FCD measures the profiles of FC for the given voxel at different scales. Resting-state functional magnetic resonance imaging (fMRI) images were obtained from patients with AD and MCI and matched healthy controls (HCs). One-way ANCOVA was used to investigate (global, long-range, and local) FCD differences among the three groups followed by post-hoc analysis controlling age, sex, and head motion.

RESULTS

The three groups exhibited significant global FCD differences in the superior frontal gyrus. The post-hoc results further showed that patients with AD had a significant increase in global FCD values than those with MCI and HCs. Patients with MCI exhibited an increased trend compared with HCs. We further identified brain regions contributing to the observed global FCD differences by conducting seed-based FC analysis. We also identified that the observed global FCD differences were the additive effects of altered FC between the superior frontal gyrus and the posterior default model network.

DISCUSSION

These results depicted the global information communication capability impairment in AD and MCI providing a new insight into the progressive brain changes from MCI to AD.