Recall and Recognition in Alzheimer's Disease and Frontotemporal Dementia

Forgetting rate for the familiarity and recollection components of recognition in amnestic mild cognitive impairment: A longitudinal study

Here we aimed to investigate the rate of forgetting of the familiarity and recollection components of recognition in patients at the onset of medial temporal lobe (MTL) pathology and destined to convert to Alzheimer's disease (AD). For this purpose, we conducted a longitudinal study of 13 patients who were diagnosed with amnestic mild cognitive impairment (a-MCI) at the first assessment and followed-up for 3 years. During this time, five patients converted to AD and eight remained in a stable condition of cognitive impairment. A group of 15 healthy subjects were enrolled as the control group (HC). In order to separately quantify the contribution of recollection and familiarity to recognition memory performance, the experimental sample was submitted to a modified version of Huppert and Piercy's procedure that included a Remember/Know paradigm. Data demonstrated that both stable and converter a-MCI patients forgot memory traces relative to the familiarity components of recognition at the same rate as HC. Conversely, converter a-MCI patients showed accelerated long-term forgetting specifically for the recollection component of recognition compared to stable a-MCI and HC. This is the first empirical demonstration that familiarity and recollection components of declarative memory are subject to different rates of forgetting in a-MCI patients as a function of their longitudinal clinical outcome. Our finding of accelerated long-term forgetting of the recollection component of recognition disclosed by converter a-MCI patients suggests that atrophy in the MTL not only interferes with the storage aspects but also disrupts the consolidation of memory traces.

Subjective clustering in patients with fronto-temporal dementia

In the behavioral variant of frontotemporal dementia (bvFTD) memory deficits have been traditionally considered as due to difficulties in encoding/retrieval frontal strategies. However, the frontal origin of memory deficits in bvFTD has been questioned and hippocampal dysfunction has been also proposed. Here we analyzed bvFTD patients' proficiency in subjectively organizing memories without an external criterion. Twenty bvFTD patients and 20 healthy individuals were assessed with memory and executive tasks. The ability to subjectively organize memories in the immediate recall of a 15 unrelated word list was measured by calculating the index of subjective clustering (ISC) based on the constancies in response order across the five consecutive free recall trials. Results revealed reduced ISC in bvFTD patients with respect to normal controls. In the bvFTD group, the ISC score correlated with the Corsi span backward score and the number of categories achieved on the Modified Card Sorting Test. The bvFTD patients' reduced ISC and its correlation with executive performance suggest that executive deficits underlie their defective strategic organization of memories. However, as ISC did not predict memory accuracy in these patients, the memory deficit may not be the mere expression of their executive difficulties.

Visuoconstructional Abilities of Patients With Subjective Cognitive Decline, Mild Cognitive Impairment and Alzheimer's Disease

BACKGROUND

Via the Vienna Visuoconstructional Test 3.0 (VVT 3.0) delayed recall we combined the assessment of visuoconstructive abilities and memory and investigated the test's potential to support diagnostic processes, including staging and the elaboration of a cognitive profile.

METHODS

We retrospectively analysed the data of 368 patients of the Department of Neurology, Medical University of Vienna, between 04/2014 and 10/2020 that had performed the VVT 3.0. Our sample involved 70 healthy controls (HC), 29 patients with subjective cognitive decline (SCD), 154 patients with mild cognitive impairment (MCI) and 115 patients with Alzheimer's disease (AD). We investigated the differences in the VVT 3.0 scores, as well as the VVT's ability to differentiate between AD and nonAD by calculating receiver-operating-characteristic (ROC) curves, ideal cut-offs and a logistic regression model.

RESULTS

Results stated that the VVT 3.0 delayed recall scores were able to differentiate between all diagnostic groups, respectively, except HC-SCD and SCD-MCI. The ROC analyses determined an AUC of 0.890, 95% CI [0.855; 0.925], P < .001, and the ideal cut-off at 29.5 points that maximised sensitivity at 0.896 and specificity at 0.81. The logistic regression model classified 83.4% of AD patients correctly and delivered a significant Cohen's Kappa of 0.619 (P < .001).

CONCLUSION

As the VVT 3.0 revealed satisfactory values of diagnostic accuracy in our sample, it could enrich clinical diagnosing. However, for more clarity about its informative value in other populations, there remains a need for future studies with other samples.

Accelerated long-term forgetting in neurodegenerative disorders: A systematic review of the literature

Accelerated Long-term Forgetting (ALF) is a memory deficit characterised by normal retention up to relatively short intervals (e.g., minutes, hours) with increased forgetting over longer periods (e.g., days, weeks). ALF is often underestimated due to a lack of common memory assessments beyond 30-60 min. The purpose of this review was to provide an overview of ALF occurrence in neurodegenerative disorders, evaluating whether it can be considered a cognitive deficit useful for diagnosing and monitoring patients. We included 19 experimental studies that investigated ALF in neurodegenerative disorders. Most papers were focused on Alzheimer's disease (AD) dementia and related forms of cognitive decline (Mild Cognitive Impairment, Subjective Cognitive decline, Pre-symptomatic subjects at risk of AD dementia). The major finding of the present work concerns the presence of ALF in very early forms of cognitive decline related to AD. These findings, supporting the hypothesis that ALF is a subtle and undetected hallmark of pre-clinical AD, highlights the importance of investigating forgetting over a longer period and devising standardised measures to be included in clinical practice.

Blood Pressure Variability and Cognitive Function: a Scoping Review

PURPOSE OF REVIEW

To conduct a scoping review of articles which have evaluated BPV and cognitive function. Articles with keywords, titles or abstracts containing the terms 'cognitive' OR 'cognition' OR 'dementia' AND 'blood pressure variability' were identified from CINAHL, Medline, PMC and Web of Science.

RECENT FINDINGS

Methods of acquisition and analysis of BPV and cognitive measurements and their relationship were extracted from selected articles. Of 656 studies identified, 53 articles were selected. Twenty-five evaluated long-term (LTBPV), nine mid-term (MTBPV), 12 short-term (STBPV) and nine very short-term BPV (VSTBPV) with conflicting findings on the relationship between BPV and cognition. Variations existed in devices, period and procedure for acquisition. The studies also utilized a wide range of methods of BPV calculation. Thirteen cognitive assessment tools were used to measure global cognition or domain functions which were influenced by the population of interest. The interpretation of available studies was hence limited by heterogeneity. There is an urgent need for standardization of BPV assessments to streamline research on BPV and cognition. Future studies should also establish whether BPV could be a potential modifiable risk factor for cognitive decline, as well as a marker for treatment response.