Barriers to Effective Memory Assessments for Alzheimer’s Disease

Parra, Mario A.

doi:10.3233/jad-215445

Cited by 12 publications

(18 citation statements)

References 75 publications

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“…Stage of Objective Memory Impairment 1, [80]) prior to tau pathology becomes more challenging to interpret. Parra [22] recently suggested the need to zoom out if we are to unveil more promising neural correlates of memory functions sensitive to AD. Future efforts will be needed to continue mapping these memory markers onto the continuum of neuropathological events that lead to AD dementia.…”

Section: Discussionmentioning

confidence: 99%

“…Stage III of Braak[20,21] corresponds to the onset of MCI (spread of pathology from the anterior medial temporal lobe (MTL) network to the posterior network). Based on the above hypothesis and that proposed by Parra[22], we predicted that the VSTMBT, as a context-free memory test, would inform on the risk of progressing from normal to pathological ageing (e.g. early MCI or objectively defined subtle cognitive decline[23]) while the FCSRT, as a context-rich memory test, would inform on the risk of progressing to AD dementia…”

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confidence: 98%

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Memory markers in the continuum of the Alzheimer’s clinical syndrome

et al. 2022

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Background The individual and complementary value of the Visual Short-Term Memory Binding Test (VSTMBT) and the Free and Cued Selective Reminding Test (FCSRT) as markers to trace the AD continuum was investigated. It was hypothesised that the VSTMBT would be an early indicator while the FCSRT would inform on imminent progression. Methods Healthy older adults (n=70) and patients with mild cognitive impairment (MCI) (n=80) were recruited and followed up between 2012 and 2017. Participants with at least two assessment points entered the study. Using baseline and follow-up assessments four groups were defined: Older adults who were healthy (HOA), with very mild cognitive but not functional impairment (eMCI), and with MCI who did and did not convert to dementia (MCI converters and non-converters). Results Only the VSTMBT predicted group membership in the very early stages (HOA vs eMCI). As the disease progressed, the FCSRT became a strong predictor excluding the VSTMB from the models. Their complementary value was high during the mid-prodromal stages and decreased in stages closer to dementia. Discussion The study supports the notion that neuropsychological assessment for AD needs to abandon the notion of one-size-fits-all. A memory toolkit for AD needs to consider tools that are early indicators and tools that suggest imminent progression. The VSTMBT and the FSCRT are such tools.

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Memory markers in the continuum of the Alzheimer’s clinical syndrome

et al. 2022

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“…Groups entering analysis of sporadic MCI were over 65 years of age while those entering analysis of familial MCI were in their 40's. Age has proved a confound when it comes to early detection of sporadic later-onset AD (Parra, 2022). Most neurocognitive changes associated to MCI linked to Alzheimer's disease are 2016) later explored similar hypothesis using EEG and behavioral measures in MCI subjects reporting very similar findings (i.e., shared neurocognitive phenotypes across disease variants).…”

Section: Discussionmentioning

confidence: 99%

Robust Assessment of EEG Connectivity Patterns in Mild Cognitive Impairment and Alzheimer's Disease

Clark¹,

Smith²,

Escudero³

et al. 2022

Front. Neuroimaging

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The prevalence of dementia, including Alzheimer's disease (AD), is on the rise globally with screening and intervention of particular importance and benefit to those with limited access to healthcare. Electroencephalogram (EEG) is an inexpensive, scalable, and portable brain imaging technology that could deliver AD screening to those without local tertiary healthcare infrastructure. We study EEG recordings of subjects with sporadic mild cognitive impairment (MCI) and prodromal familial, early-onset, AD for the same working memory tasks using high- and low-density EEG, respectively. A challenge in detecting electrophysiological changes from EEG recordings is that noise and volume conduction effects are common and disruptive. It is known that the imaginary part of coherency (iCOH) can generate functional connectivity networks that mitigate against volume conduction, while also erasing true instantaneous activity (zero or π-phase). We aim to expose topological differences in these iCOH connectivity networks using a global network measure, eigenvector alignment (EA), shown to be robust to network alterations that emulate the erasure of connectivities by iCOH. Alignments assessed by EA capture the relationship between a pair of EEG channels from the similarity of their connectivity patterns. Significant alignments—from comparison with random null models—are seen to be consistent across frequency ranges (delta, theta, alpha, and beta) for the working memory tasks, where consistency of iCOH connectivities is also noted. For high-density EEG recordings, stark differences in the control and sporadic MCI results are observed with the control group demonstrating far more consistent alignments. Differences between the control and pre-dementia groupings are detected for significant correlation and iCOH connectivities, but only EA suggests a notable difference in network topology when comparing between subjects with sporadic MCI and prodromal familial AD. The consistency of alignments, across frequency ranges, provides a measure of confidence in EA's detection of topological structure, an important aspect that marks this approach as a promising direction for developing a reliable test for early onset AD.

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“…This ensures that each of the six visual stimuli is perceived as an individual object or at least complies with the level of conjunctions needed for PRC involvement (Cowell et al, 2010; Wagemans et al, 2012). Last, we intended to develop a cognitive measure for AD, that is affordable and broadly applicable as well as independent of sociocultural factors (e.g., nonverbal; Parra, 2022).…”

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Can you find it? Novel oddity detection task for the early detection of Alzheimer’s disease.

Frei¹,

Berres²,

Kivisaari³

et al. 2023

Neuropsychology

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Objective: We aimed to develop a measure to specifically assess the functioning of the perirhinal cortex (PRC), a brain structure affected very early in Alzheimer's disease (AD) pathology. In this novel task, participants were shown arrays of six complex figures and had to identify the "odd-one." Method: The pilot study included 50 normal controls (NCs) and 50 patients in very early stages of AD. Participants completed the task and received MRI scanning. Best differentiating items were determined and applied in a validation study including 25 NCs, 27 early-stage AD patients, and 26 patients with major depression. Logistic regression models investigated if task performance predicted group membership. Task performance was then related to whole-brain gray matter integrity. As proof of concept, cortical thickness values of four regions of interest (ROIs; e.g., medial PRC and entorhinal cortex [ERC]) were compared between the groups. The associations of task performance and cortical thickness of the ROIs were investigated using linear models. Results: Task performance showed good discriminative ability between early-stage AD patients and NCs. Whole-brain analyses revealed four significant clusters ( p < .001) with peak voxels in parahippocampal regions including PRC and ERC. ROI analyses showed distinctly reduced cortical thickness in the AD group compared to both other groups in the medial PRC and ERC ( p ≤ .001). Task performance modeled by ROI cortical thickness did not achieve significant results. Conclusion: Although further validation is needed, especially with age-matched participant groups, these findings indicate that the task detects early cognitive impairment related to AD. Neuropsychology

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Barriers to Effective Memory Assessments for Alzheimer’s Disease

Cited by 12 publications

References 75 publications

Memory markers in the continuum of the Alzheimer’s clinical syndrome

Memory markers in the continuum of the Alzheimer’s clinical syndrome

Robust Assessment of EEG Connectivity Patterns in Mild Cognitive Impairment and Alzheimer's Disease

Can you find it? Novel oddity detection task for the early detection of Alzheimer’s disease.

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