Characterizing cognitive inhibitory deficits in mild cognitive impairment

Subjective Cognitive Impairment Can Be Detected from the Decline of Complex Cognition: Findings from the Examination of Remedes 4 Alzheimer's (R4Alz) Structural Validity

R4Alz is utilized for the early detection of minor neurocognitive disorders. It was designed to assess three main dimensions of cognitive-control abilities: working-memory capacity, attentional control, and executive functioning.

OBJECTIVES

To reveal the cognitive-control dimensions that can differentiate between adults and older adults with healthy cognition, people with subjective cognitive impairment, and people diagnosed with mild cognitive impairment by examining the factorial structure of the R4Alz tool.

METHODS

The study comprised 404 participants: (a) healthy adults (n = 192), (b) healthy older adults (n = 29), (c) people with SCI (n = 74), and (d) people diagnosed with MCI (n = 109). The R4Alz battery was administered to all participants, including tests that assess short-term memory storage, information processing, information updating in working memory, and selective, sustained and divided attention), task/rule-switching, inhibitory control, and cognitive flexibility.

RESULTS

A two-factorial structural model was confirmed for R4Alz, with the first factor representing "fluid intelligence (FI)" and the second factor reflecting "executive functions (EF)". Both FI and EFs discriminate among all groups.

CONCLUSIONS

The R4Alz battery presents sound construct validity, evaluating abilities in FI and EF. Both abilities can differentiate very early cognitive impairment (SCI) from healthy cognitive aging and MCI.

Sulcal Morphometry Predicts Mild Cognitive Impairment Conversion to Alzheimer's Disease

Background

Being able to differentiate mild cognitive impairment (MCI) patients who would eventually convert (MCIc) to Alzheimer's disease (AD) from those who would not (MCInc) is a key challenge for prognosis.

Objective

This study aimed to investigate the ability of sulcal morphometry to predict MCI progression to AD, dedicating special attention to an accurate identification of sulci.

Methods

Twenty-five AD patients, thirty-seven MCI and twenty-five healthy controls (HC) underwent a brain-MR protocol (1.5T scanner) including a high-resolution T1-weighted sequence. MCI patients underwent a neuropsychological assessment at baseline and were clinically re-evaluated after a mean of 2.3 years. At follow-up, 12 MCI were classified as MCInc and 25 as MCIc. Sulcal morphometry was investigated using the BrainVISA framework. Consistency of sulci across subjects was ensured by visual inspection and manual correction of the automatic labelling in each subject. Sulcal surface, depth, length, and width were retrieved from 106 sulci. Features were compared across groups and their classification accuracy in predicting MCI conversion was tested. Potential relationships between sulcal features and cognitive scores were explored using Spearman's correlation.

Results

The width of sulci in the temporo-occipital region strongly differentiated between each pair of groups. Comparing MCIc and MCInc, the width of several sulci in the bilateral temporo-occipital and left frontal areas was significantly altered. Higher width of frontal sulci was associated with worse performances in short-term verbal memory and phonemic fluency.

Conclusions

Sulcal morphometry emerged as a strong tool for differentiating HC, MCI, and AD, demonstrating its potential prognostic value for the MCI population.

A Log File Analysis on the Validity of Partial Solutions in Figural Matrices Tests

As a component of many intelligence test batteries, figural matrices tests are an effective way to assess reasoning, which is considered a core ability of intelligence. Traditionally, the sum of correct items is used as a performance indicator (total solution procedure). However, recent advances in the development of computer-based figural matrices tests allow additional indicators to be considered for scoring. In two studies, we focused on the added value of a partial solution procedure employing log file analyses from a computer-based figural matrices test. In the first study (n = 198), we explored the internal validity of this procedure by applying both an exploratory bottom-up approach (using sequence analyses) and a complementary top-down approach (using rule jumps, an indicator taken from relevant studies). Both approaches confirmed that higher scores in the partial solution procedure were associated with higher structuredness in participants' response behavior. In the second study (n = 169), we examined the external validity by correlating the partial solution procedure in addition to the total solution procedure with a Grade Point Average (GPA) criterion. The partial solution procedure showed an advantage over the total solution procedure in predicting GPA, especially at lower ability levels. The implications of the results and their applicability to other tests are discussed.

SMARTfit Dual-Task Exercise Improves Cognition and Physical Function in Older Adults With Mild Cognitive Impairment: Results of a Community-Based Pilot Study

Mild cognitive impairment is an intermediate state between the cognitive decline often experienced in normal aging and dementia that affects 15% of Americans over 65 years of age. Our communities have an opportunity to support the development and adoption of evidence-based programs to help older adults preserve cognition and physical function. In partnership with a local urban YMCA in an underserved, predominantly minority neighborhood, we tested the appeal and therapeutic benefits of SMARTfit training among older adults with mild cognitive impairment. The participants reported a positive training experience. After 12 weeks of dual-task training, Trail-Making Test and Stroop Color-Word Interference Test scores improved, as did scores on the Short Physical Performance Battery. Results of our SMARTfit dual-task training intervention are encouraging. Larger randomized controlled trials must further investigate the development, implementation, and therapeutic impacts of SMARTfit dual-task training on cognitive and physical function in aging.

The Ability to Use Contextual Information in Object and Scene Recognition in Patients with Mild Cognitive Impairment

BACKGROUND

The ability to understand and make use of object-scene relationships are critical for object and scene recognition.

OBJECTIVE

The current study assessed whether patients with mild cognitive impairment (MCI), possibly in the preclinical phase of Alzheimer's disease, exhibited impairment in processing contextual information in scene and object recognition.

METHODS

In Experiment 1, subjects viewed images of foreground objects in either semantic consistent or inconsistent scenes under no time pressure, and they verbally reported the names of foreground objects and backgrounds. Experiment 2 replicated Experiment 1, except that subjects were required to name scene first. Experiment 3 examined object and scene recognition accuracy baselines, recognition difficulty, familiarity with objects/scenes, and object-scene consistency judgements.

RESULTS

There were contextual consistency effects on scene recognition for MCI and healthy subjects, regardless of response sequence. Scenes were recognized more accurately under the consistent condition than the inconsistent condition. Additionally, MCI patients were more susceptible to incongruent contextual information, possibly due to inhibitory deficits or over-dependence on semantic knowledge. However, no significant differences between MCI and healthy subjects were observed in consistency judgement, recognition accuracy, recognition difficulty and familiarity rating, suggesting no significant impairment in object and scene knowledge among MCI subjects.

CONCLUSIONS

The study indicates that MCI patients retain relatively intact contextual processing ability but may exhibit inhibitory deficits or over-reliance on semantic knowledge.

Higher-Level Executive Functions in Healthy Elderly and Mild Cognitive Impairment: A Systematic Review

Mild Cognitive Impairment (MCI) is a clinical syndrome characterized by a moderate decline in one or more cognitive functions with a preserved autonomy in daily life activities. MCI exhibits cognitive, behavioral, psychological symptoms. The executive functions (EFs) are key functions for everyday life and physical and mental health and allow for the behavior to adapt to external changes. Higher-level executive functions develop from basic EFs (inhibition, working memory, attentional control, and cognitive flexibility). They are planning, reasoning, problem solving, and fluid intelligence (Gf). This systematic review investigates the relationship between higher-level executive functions and healthy and pathological aging, assuming the role of executive functions deficits as a predictor of cognitive decline. The systematic review was conducted according to the PRISMA Statement. A total of 73 studies were identified. The results indicate that 65.8% of the studies confirm significant EFs alterations in MCI (56.8% planning, 50% reasoning, 100% problem solving, 71.4% fluid intelligence). These results seem to highlight a strong prevalence of higher-level executive functions deficits in MCI elderly than in healthy elderly.

Decline in the integration of top-down and bottom-up attentional control in older adults with mild cognitive impairment

Individuals with mild cognitive impairment (MCI) have deficits in goal-directed top-down and stimulus-driven bottom-up attentional control. However, it remains unclear whether and how the interaction between the two processes is altered in individuals with MCI. We collected electroencephalography (EEG) data from 30 older adults with MCI and 30 demographically matched healthy controls (HCs) when they were performing a perceptual decision-making task, in which we manipulated the cognitive load involved in task-relevant top-down processing and the surprise level involved in task-irrelevant bottom-up processing. We found the significant group difference in the interaction between top-down and bottom-up processes. HCs showed enlarged P3 and strengthened event-related microstate C on high (vs. low) surprise level trials under high cognitive load, while there was no such surprise effect suggesting distraction under low cognitive load. In contrast, participants with MCI showed increased P2 and P3 amplitudes and strengthened microstates C and D on high (vs. low) surprise level trials under low cognitive load yet no surprise effect under high load. These results suggested that participants with MCI were distracted by task-irrelevant information under low cognitive load, while under high load, they might experience a passive inhibition on the task-irrelevant bottom-up processing because of the exhaustion of attentional resources; in addition, this altered interaction observed in the MCI group occurred at the stages of selective attention and uncertainty reduction.

Reaction time intra-individual variability reveals inhibitory deficits in single- and multiple-domain amnestic mild cognitive impairment

OBJECTIVES

Amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimer's disease and other dementias, is characterized by episodic memory impairment. Recent evidence has shown inhibitory control deficits in aMCI, but the extent of these deficits across inhibitory domains (i.e., response inhibition and interference control) and aMCI subtypes (i.e., single- versus multiple-domain) remains unclear. Few studies have included response time intra-individual variability (RT IIV) in these efforts. The aim of this study was to compare response inhibition and interference control between aMCI subtypes using measures of accuracy, mean RT, and RT IIV.

METHOD

We report data from 34 individuals with single-domain aMCI (sdaMCI, 66-86 years), 20 individuals with multiple-domain aMCI (mdaMCI, 68-88 years), and 52 healthy controls (64-88 years) who completed tasks of response inhibition (Go-NoGo) and interference control (Flanker). Group differences in accuracy, mean RT, and RT IIV were examined for both tasks.

RESULTS

Individuals with mdaMCI had higher RT IIV than the other groups on both tasks. In RT IIV, we observed an interference control deficit in mdaMCI and sdaMCI relative to healthy controls, a finding not observed through accuracy or mean RT.

DISCUSSION

RT IIV may detect subtle differences in inhibition deficits between aMCI subtypes that may not be evident with conventional behavioral measures. Findings support the supplementary use of RT IIV when assessing early executive function deficits.

Effects of Candesartan vs Lisinopril on Neurocognitive Function in Older Adults With Executive Mild Cognitive Impairment: A Randomized Clinical Trial

IMPORTANCE

Observational studies have suggested that angiotensin receptor blockers are associated with a unique cognitive protection. It is unclear if this is due to reduced blood pressure (BP) or angiotensin receptors type 1 blockade.

OBJECTIVE

To determine neurocognitive effects of candesartan vs lisinopril in older adults with mild cognitive impairment (MCI).

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial included participants aged 55 years or older with MCI and hypertension. Individuals were withdrawn from prior antihypertensive therapy and randomized in a 1 to 1 ratio to candesartan or lisinopril from June 2014 to December 2018. Participants underwent cognitive assessments at baseline and at 6 and 12 months. Brain magnetic resonance images were obtained at baseline and 12 months. This intent-to-treat study was double-blind and powered for a sample size accounting for 20% dropout. Data were analyzed from May to October 2019.

INTERVENTIONS

Escalating doses of oral candesartan (up to 32 mg) or lisinopril (up to 40 mg) once daily. Open-label antihypertensive drug treatments were added as needed to achieve BP less than 140/90 mm Hg.

MAIN OUTCOMES AND MEASURES

The primary outcome was executive function (measured using the Trail Making Test, Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research tool) and secondary outcomes were episodic memory (measured using the Hopkins Verbal Learning Test-Revised) and microvascular brain injury reflected by magnetic resonance images of white matter lesions.

RESULTS

Among 176 randomized participants (mean [SD] age, 66.0 [7.8] years; 101 [57.4%] women; 113 [64.2%] African American), 87 were assigned to candesartan and 89 were assigned to lisinopril. Among these, 141 participants completed the trial, including 77 in the candesartan group and 64 in the lisinopril group. Although the lisinopril vs candesartan groups achieved similar BP (12-month mean [SD] systolic BP: 130 [17] mm Hg vs 134 [20] mm Hg; P = .20; 12-month mean [SD] diastolic BP: 77 [10] mm Hg vs 78 [11] mm Hg; P = .52), candesartan was superior to lisinopril on the primary outcome of executive function measured by Trail Making Test Part B (effect size [ES] = -12.8 [95% CI, -22.5 to -3.1]) but not Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research score (ES = -0.03 [95% CI, -0.08 to 0.03]). Candesartan was also superior to lisinopril on the secondary outcome of Hopkins Verbal Learning Test-Revised delayed recall (ES = 0.4 [95% CI, 0.02 to 0.8]) and retention (ES = 5.1 [95% CI, 0.7 to 9.5]).

CONCLUSIONS AND RELEVANCE

These findings suggest that in older adults with MCI, 1-year treatment with candesartan had superior neurocognitive outcomes compared with lisinopril. These effects are likely independent of the BP-lowering effect of candesartan.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01984164.

A new tool to assess amnestic mild cognitive impairment in Turkish older adults: virtual supermarket (VSM)

The purpose of this study was to investigate cognitive functioning by administering the Virtual Supermarket (VSM) test in patients with amnestic mild cognitive impairment (aMCI, N = 37) and age and education-matched healthy controls (HCs, N = 52). An extensive neuropsychological test battery and the VSM were administered to all participants. The aMCI group exhibited lower performance and required more time to complete the VSM compared to HCs. Also, aMCI-Multiple Domain (aMCI-MD) patients performed worse in the "Correct Types", "Correct Quantities", "Bought Unlisted", "Correct Money" variables compared to HCs. Moreover, aMCI-SD patients displayed lower performance in "Bought Unlisted" and "Correct Money" variables compared to HCs. The VSM variables correlated with established neuropsychological test scores. The VSM test was found to discriminate between aMCI and HCs with a correct classification rate (CCR) of 81%. This is a preliminary study showing that the VSM is a valid, brief and user-friendly test. .

Reduced Capacity of Cognitive Control in Older Adults with Mild Cognitive Impairment

Cognitive control for the coordination of mental operations is essential in normal cognitive functioning of daily life. Although the decline of cognitive control in older adults with mild cognitive impairment (MCI) has been demonstrated, whether this decline is a core deficit in MCI remains unclear. In this study, we employed a perceptual decision-making task to estimate the capacity of cognitive control (CCC) in older adults with MCI (n = 55) and the age-, sex-, and education-matched healthy controls (HC, n = 55) selected based on a commonly used battery of ten neuropsychological tests in five cognitive domains. We found that the CCC was significantly correlated to the neuropsychological measures of the battery. The mean CCC was significantly lower in the MCI group (3.06 bps) than in the HC group (3.59 bps) and significantly lower in the amnestic MCI subgroup (2.90 bps) than in the nonamnestic MCI subgroup (3.22 bps). In detecting and classifying MCI using machine learning, the classifier with the CCC as the input feature outperformed the overall classification with neuropsychological measures in a single cognitive domain. The classification performance was significantly increased when the CCC was included as a feature in addition to measures in a single domain, and the CCC served as a key feature in optimal classifiers with inputs from multiple domains. These results support the hypothesis that the decline in cognitive control is a core deficit in MCI and suggest that the CCC may serve as a key index in the diagnosis of MCI.

Types of errors on a semantic interference task in mild cognitive impairment and dementia

OBJECTIVE

This research aimed to determine whether qualitative analysis of different types of intrusion errors on a verbal cognitive task was useful in detecting subtle cognitive impairment in preclinical stages prior to the progression to dementia.

METHOD

Different types of semantic intrusions on the Loewenstein-Acevedo Scales of Semantic Interference and Learning (LASSI-L) were compared across 160 individuals diagnosed as cognitively normal (CN), amnestic Mild Cognitive Impairment (aMCI), and dementia. The sample included Hispanics and non-Hispanic European Americans.

RESULTS

Across diagnostic groups, the most common type of intrusion error was actual targets presented from a competing word list under conditions eliciting proactive semantic interference (PSI), and retroactive semantic interference (RSI), followed by intrusions that represented one of three overlapping semantic categories but none of the targets from List A or B. Nonsemantic intrusions rarely occurred. These competing list intrusions (CLI) and semantically related intrusions (SRI) differentiated between aMCI and CN participants. Further, these intrusion error were related to brain amyloid load, indicating their importance as potential primary markers of AD-related neurodegeneration. Ethnicity effects were not seen across the types of intrusion errors.

CONCLUSIONS

Two types of intrusion errors (CLI and SRI) showed differences between the CN and aMCI group, with the aMCI group evidencing a higher rate of these intrusion errors compared with the CN group. These results support previous literature about the LASSI-L's sensitivity at the earliest stages of abnormal aging. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Recovery from Proactive Semantic Interference and MRI Volume: A Replication and Extension Study

BACKGROUND

The rise in incidence of Alzheimer's disease (AD) has led to efforts to advance early detection of the disease during its preclinical stages. To achieve this, the field needs to develop more sensitive cognitive tests that relate to biological markers of disease pathology. Failure to recover from proactive interference (frPSI) is one such cognitive marker that is associated with volumetric reductions in the hippocampus, precuneus, and other AD-prone regions, and to amyloid load in the brain.

OBJECTIVE

The current study attempted to replicate and extend our previous findings that frPSI is a sensitive marker of early AD, and related to a unique pattern of volumetric loss in AD prone areas.

METHODS

Three different memory measures were examined relative to volumetric loss and cortical thickness among 45 participants with amnestic mild cognitive impairment.

RESULTS

frPSI was uniquely associated with reduced volumes in the hippocampus (r = 0.50) precuneus (r = 0.41), and other AD prone regions, replicating previous findings. Strong associations between frPSI and lower entorhinal cortex volumes and cortical thickness (r≥0.60) and precuneus (r = 0.50) were also observed.

CONCLUSION

Unique and strong associations between volumetric reductions and frPSI as observed by Loewenstein and colleagues were replicated. Together with cortical thickness findings, these results indicate that frPSI is worthy of further study as a sensitive and early cognitive marker of AD.

A novel cognitive assessment paradigm to detect Pre-mild cognitive impairment (PreMCI) and the relationship to biological markers of Alzheimer's disease

OBJECTIVE

A number of older adults obtain normal scores on formal cognitive tests, but present clinical concerns that raise suspicion of cognitive decline. Despite not meeting full criteria for Mild Cognitive Impairment (MCI), these PreMCI states confer risk for progression to Alzheimer's disease (AD). This investigation addressed a pressing need to identify cognitive measures that are sensitive to PreMCI and are associated with brain biomarkers of neurodegeneration.

METHOD

Participants included 49 older adults with a clinical history suggestive of cognitive decline but normal scores on an array of neuropsychological measures, thus not meeting formal criteria for MCI. The performance of these PreMCI participants were compared to 117 cognitively normal (CN) elders on the LASSI-L, a cognitive stress test that uniquely assesses the failure to recover from proactive semantic interference effects (frPSI). Finally, a subset of these individuals had volumetric analyses based on MRI scans.

RESULTS

PreMCI participants evidenced greater LASSI- L deficits, particularly with regards to frPSI and delayed recall, relative to the CN group. No differences on MRI measures were observed. Controlling for false discovery rate (FDR), frPSI was uniquely related to increased dilatation of the inferior lateral ventricle and decreased MRI volumes in the hippocampus, precuneus, superior parietal region, and other AD prone areas. In contrast, other LASSI-L indices and standard memory tests were not related to volumetric findings.

CONCLUSIONS

Despite equivalent performance on traditional memory measures, the frPSI distinguished between PreMCI and CN elders and was associated with reductions in brain volume in numerous AD-relevant brain regions.

Working Memory Training for Healthy Older Adults: The Role of Individual Characteristics in Explaining Short- and Long-Term Gains

Objective: The aim of the present study was to explore whether individual characteristics such as age, education, vocabulary, and baseline performance in a working memory (WM) task-similar to the one used in the training (criterion task)-predict the short- and long-term specific gains and transfer effects of a verbal WM training for older adults. Method: Four studies that adopted the Borella et al. (2010) verbal WM training procedure were found eligible for our analysis as they included: healthy older adults who attended either the training sessions (WM training group), or alternative activities (active control group); the same measures for assessing specific gains (on the criterion WM task), and transfer effects (nearest on a visuo-spatial WM task, near on short-term memory tasks and far on a measure of fluid intelligence, a measure of processing speed and two inhibitory measures); and a follow-up session. Results: Linear mixed models confirmed the overall efficacy of the training, in the short-term at least, and some maintenance effects. In the trained group, the individual characteristics considered were found to contribute (albeit only modestly in some cases) to explaining the effects of the training. Conclusions: Overall, our findings suggest the importance of taking individual characteristics and individual differences into account when examining WM training gains in older adults.