Perceptual and motor inhibitory abilities in normal aging and Alzheimer disease (AD): a preliminary study

The Use of Digital Technology to Assess Cognitive Function in Tunisian Adults

Background: There has been increasing evidence and support for the use of digital technology in the cognitive health field. Despite the growing use of innovative digital technology to assess cognitive function, such technology remains scarce in Arabic countries, particularly in Tunisia. Objective: To investigate the effectiveness of a digitally delivered cognitive assessment battery in differentiating varying degrees of cognitive function in older Tunisian adults. Methods: One hundred fifty-five Tunisian older adults (age: 62.24±7.52 years) were assigned to one of four groups: healthy controls (HC), at-risk (AR), mild cognitive impairment (MCI), and Alzheimer’s disease (AD). Participants completed a translated version of the Neurotrack digital cognitive battery. Results: The AD group performed significantly lower on the associative learning (p = 0.01) and associative memory assessments (p = 0.002), than the HC and AR groups. The AD group also performed worse on the inhibition measure (p = 0.008) than the HC, AR, and MCI groups. For recognition memory, the was a significant difference between all four groups (p <  0.0005), with AD having the lowest scores followed by the MCI, AR, and HC groups, respectively. There were no significant differences observed on attention, executive function and processing speed performance between the four groups (p >  0.05). Conclusion: The use of digital technology appears to be a viable solution to current cognitive assessment challenges for assessing cognitive function in a Tunisian population. These findings provide further support for the use of digital technology in cognitive assessment, particularly in understudied populations.

Interactions Between Aging and Alzheimer's Disease on Structural Brain Networks

Normative aging and Alzheimer's disease (AD) propagation alter anatomical connections among brain parcels. However, the interaction between the trajectories of age- and AD-linked alterations in the topology of the structural brain network is not well understood. In this study, diffusion-weighted magnetic resonance imaging (MRI) datasets of 139 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database were used to document their structural brain networks. The 139 participants consist of 45 normal controls (NCs), 37 with early mild cognitive impairment (EMCI), 27 with late mild cognitive impairment (LMCI), and 30 AD patients. All subjects were further divided into three subgroups based on their age (56-65, 66-75, and 71-85 years). After the structural connectivity networks were built using anatomically-constrained deterministic tractography, their global and nodal topological properties were estimated, including network efficiency, characteristic path length, transitivity, modularity coefficient, clustering coefficient, and betweenness. Statistical analyses were then performed on these metrics using linear regression, and one- and two-way ANOVA testing to examine group differences and interactions between aging and AD propagation. No significant interactions were found between aging and AD propagation in the global topological metrics (network efficiency, characteristic path length, transitivity, and modularity coefficient). However, nodal metrics (clustering coefficient and betweenness centrality) of some cortical parcels exhibited significant interactions between aging and AD propagation, with affected parcels including left superior temporal, right pars triangularis, and right precentral. The results collectively confirm the age-related deterioration of structural networks in MCI and AD patients, providing novel insight into the cross effects of aging and AD disorder on brain structural networks. Some early symptoms of AD may also be due to age-associated anatomic vulnerability interacting with early anatomic changes associated with AD.

Perceptual Inhibition Associated with Sensory Integration for Balance in Older Adults

AIMS

Inhibition associated with perception has been implicated in sensory integration processes for balance when sensory conflict occurs. The current study examines the associations of three measures of inhibition (perceptual inhibition, motor inhibition, and Stroop interference) with standing balance under sensory conflict conditions in younger and older adults.

METHODS

Perceptual inhibition, motor inhibition, and Stroop interference were measured in younger and older subjects. Standing balance under conditions of sensory conflict was evaluated using a modified dynamic posturography protocol. Correlative analysis was performed to examine the associations between the inhibition measures and sway.

RESULTS

In older adults only, perceptual inhibition was correlated with sway when sensory conflict was present. Stroop interference and motor inhibition were not significantly correlated with sway under any posturography conditions.

CONCLUSION

Measures of perceptual inhibition are associated with reduced sensory integration capability for balance during sensory conflict conditions in older adults.

Executive Functions in Alzheimer Disease: A Systematic Review

Alzheimer's disease is a severe irreversible syndrome, characterized by a slow and progressive cognitive decline that interferes with the standard instrumental and essential functions of daily life. Promptly identifying the impairment of particular cognitive functions could be a fundamental condition to limit, through preventive or therapeutic interventions, the functional damages found in this degenerative dementia. This study aims to analyse, through a systematic review of the studies, the sensitivity of four experimental paradigms (Wisconsin Card Sorting Test, Stroop Task, Go/No-Go Task, and Flanker Task) considered as golden standard instruments for executive functions assessment in elderly subjects affected by Alzheimer dementia. This review was carried out according to the PRISMA method. Forty-five studies comparing the executive performance of patients with Alzheimer's dementia (diagnosed according to different classification criteria for dementia) and healthy elderly patients both over the age of sixty, were selected. For the research, PubMed, PsycINFO, PsycArticles databases were used. The study highlighted the importance of using standard protocols to evaluate executive dysfunction in Alzheimer's disease. The Stroop task allows discriminating better between healthy and pathological aging.

Modulating functional connectivity with non-invasive brain stimulation for the investigation and alleviation of age-associated declines in response inhibition: A narrative review

Response inhibition, the ability to withhold a dominant and prepotent response following a change in circumstance or sensory stimuli, declines with advancing age. While non-invasive brain stimulation (NiBS) has shown promise in alleviating some cognitive and motor functions in healthy older individuals, NiBS research focusing on response inhibition has mostly been conducted on younger adults. These extant studies have primarily focused on modulating the activity of distinct neural regions known to be critical for response inhibition, including the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (pre-SMA). However, given that changes in structural and functional connectivity have been associated with healthy aging, this review proposes that NiBS protocols aimed at modulating the functional connectivity between the rIFG and pre-SMA may be the most efficacious approach to investigate-and perhaps even alleviate-age-related deficits in inhibitory control.