So Close Yet So Far: Executive Contribution to Memory Processing in Behavioral Variant Frontotemporal Dementia

Neuropsychological Assessment for Early Detection and Diagnosis of Dementia: Current Knowledge and New Insights

Dementia remains an underdiagnosed syndrome, and there is a need to improve the early detection of cognitive decline. This narrative review examines the role of neuropsychological assessment in the characterization of cognitive changes associated with dementia syndrome at different states. The first section describes the early indicators of cognitive decline and the major barriers to their identification. Further, the optimal cognitive screening conditions and the most widely accepted tests are described. The second section analyzes the main differences in cognitive performance between Alzheimer's disease and other subtypes of dementia. Finally, the current challenges of neuropsychological assessment in aging/dementia and future approaches are discussed. Essentially, we find that current research is beginning to uncover early cognitive changes that precede dementia, while continuing to improve and refine the differential diagnosis of neurodegenerative disorders that cause dementia. However, neuropsychology faces several barriers, including the cultural diversity of the populations, a limited implementation in public health systems, and the adaptation to technological advances. Nowadays, neuropsychological assessment plays a fundamental role in characterizing cognitive decline in the different stages of dementia, but more efforts are needed to develop harmonized procedures that facilitate its use in different clinical contexts and research protocols.

Detecting Alzheimer's Disease Stages and Frontotemporal Dementia in Time Courses of Resting-State fMRI Data Using a Machine Learning Approach

Early, accurate diagnosis of neurodegenerative dementia subtypes such as Alzheimer's disease (AD) and frontotemporal dementia (FTD) is crucial for the effectiveness of their treatments. However, distinguishing these conditions becomes challenging when symptoms overlap or the conditions present atypically. Resting-state fMRI (rs-fMRI) studies have demonstrated condition-specific alterations in AD, FTD, and mild cognitive impairment (MCI) compared to healthy controls (HC). Here, we used machine learning to build a diagnostic classification model based on these alterations. We curated all rs-fMRIs and their corresponding clinical information from the ADNI and FTLDNI databases. Imaging data underwent preprocessing, time course extraction, and feature extraction in preparation for the analyses. The imaging features data and clinical variables were fed into gradient-boosted decision trees with fivefold nested cross-validation to build models that classified four groups: AD, FTD, HC, and MCI. The mean and 95% confidence intervals for model performance metrics were calculated using the unseen test sets in the cross-validation rounds. The model built using only imaging features achieved 74.4% mean balanced accuracy, 0.94 mean macro-averaged AUC, and 0.73 mean macro-averaged F1 score. It accurately classified FTD (F1 = 0.99), HC (F1 = 0.99), and MCI (F1 = 0.86) fMRIs but mostly misclassified AD scans as MCI (F1 = 0.08). Adding clinical variables to model inputs raised balanced accuracy to 91.1%, macro-averaged AUC to 0.99, macro-averaged F1 score to 0.92, and improved AD classification accuracy (F1 = 0.74). In conclusion, a multimodal model based on rs-fMRI and clinical data accurately differentiates AD-MCI vs. FTD vs. HC.

Genuine Memory Deficits as Assessed by the Free and Cued Selective Reminding Test (FCSRT) in the Behavioural Variant of Frontotemporal Dementia. A Systematic Review and Meta-analysis Study

The current diagnostic criteria for the behavioural variant of frontotemporal dementia (bvFTD) foresee a relative sparing of long-term memory. Although bvFTD patients were thought to report secondary memory deficits associated with prefrontal dysfunctions, some studies indicated the presence of a "genuine memory deficit" related to mesial temporal lobe dysfunctions. Among various neuropsychological tests, the Free and Cue Selective Reminding Test (FCSRT) has been recommended to distinguish genuine from apparent amnesia. We conducted a systematic review and a random effect Bayesian meta-analysis to evaluate the nature and severity of memory deficit in bvFTD. Our objective was to determine whether the existing literature offers evidence of genuine or apparent amnesia in patients with bvFTD, as assessed via the FCSRT. On 06/19/2021, we conducted a search across four databases (PMC, Scopus, Web of Science, and PubMed). We included all studies that evaluated memory performance using the FCSRT in patients with bvFTD, as long as they also included either cognitively unimpaired participants or AD groups. We tested publication bias through the Funnel plot and Egger's test. To assess the quality of studies, we used the Newcastle-Ottawa quality assessment scale adapted for cross-sectional studies. We included 16 studies in the meta-analysis. The results showed that bvFTD patients perform better than AD patients (pooled effects between 0.95 and 1.14), as their memory performance stands between AD and control groups (pooled effects between - 2.19 and - 1.25). Moreover, patients with bvFTD present both genuine and secondary memory disorders. As a major limitation of this study, due to our adoption of a rigorous methodology and stringent inclusion criteria, we ended up with just 16 studies. Nonetheless, our robust findings can contribute to the ongoing discussion on international consensus criteria for bvFTD and the selection of appropriate neuropsychological tools to facilitate the differential diagnosis between AD and bvFTD.

Episodic Memory in Amnestic Behavioral Frontotemporal Dementia and Alzheimer's Disease

Behavioral frontotemporal dementia (bvFTD) may present with episodic memory deficits. In 38 patients with bvFTD and 61 with Alzheimer's disease (AD) specific measures of verbal memory (learning curves and serial position effects) were studied through the Rey Auditory Verbal Learning test. Forty-two percent of bvFTD showed deficits of delayed recall memory similar to that found in AD including the serial position effects. Amnestic bvFTD had more severe atrophy in the left mesial temporal lobe than non-amnestic bvFTD. AD-like memory deficits are not infrequent in bvFTD and may be in part related to mesial temporal lobe atrophy.

Multidimensional Clinical Assessment in Frontotemporal Dementia and Its Spectrum in Latin America and the Caribbean: A Narrative Review and a Glance at Future Challenges

Frontotemporal dementia (FTD) is the third most common form of dementia across all age groups and is a leading cause of early-onset dementia. The Frontotemporal dementia (FTD) includes a spectrum of diseases that are classified according to their clinical presentation and patterns of neurodegeneration. There are two main types of FTD: behavioral FTD variant (bvFTD), characterized by a deterioration in social function, behavior, and personality; and primary progressive aphasias (PPA), characterized by a deficit in language skills. There are other types of FTD-related disorders that present motor impairment and/or parkinsonism, including FTD with motor neuron disease (FTD-MND), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS). The FTD and its associated disorders present great clinical heterogeneity. The diagnosis of FTD is based on the identification through clinical assessments of a specific clinical phenotype of impairments in different domains, complemented by an evaluation through instruments, i.e., tests and questionnaires, validated for the population under study, thus, achieving timely detection and treatment. While the prevalence of dementia in Latin America and the Caribbean (LAC) is increasing rapidly, there is still a lack of standardized instruments and consensus for FTD diagnosis. In this context, it is important to review the published tests and questionnaires adapted and/or validated in LAC for the assessment of cognition, behavior, functionality, and gait in FTD and its spectrum. Therefore, our paper has three main goals. First, to present a narrative review of the main tests and questionnaires published in LAC for the assessment of FTD and its spectrum in six dimensions: (i) Cognitive screening; (ii) Neuropsychological assessment divided by cognitive domain; (iii) Gait assessment; (iv) Behavioral and neuropsychiatric symptoms; (v) Functional assessment; and (vi) Global Rating Scale. Second, to propose a multidimensional clinical assessment of FTD in LAC identifying the main gaps. Lastly, it is proposed to create a LAC consortium that will discuss strategies to address the current challenges in the field.

An autopsy case of Alzheimer's disease with amygdala-predominant Lewy pathology presenting with frontotemporal dementia-like psychiatric symptoms

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are progressive neurodegenerative diseases associated with several cognitive and behavioral symptoms. It is sometimes difficult to distinguish AD from FTD in a patient because both of them can exhibit clinical overlap. In the present study, we report a case of a patient who showed sychiatric symptoms mimicking the behavioral variant of FTD (bvFTD) and combined AD amygdala-predominant Lewy pathologies on autopsy. The patient was a Japanese man who developed personality changes in his late 50s, presenting with obsessive-compulsive stereotypical behavior, stereotypy of speech, behavioral disinhibition, inertia, loss of empathy or sympathy, change in eating habits, and stimulus-bound behavior. He also frequently left during medical examinations. Eventually, he was clinically diagnosed as having possible bvFTD, according to the International Consensus Criteria for bvFTD. The patient died of systemic metastasis of gastric cancer at 69 years of age. Postmortem neuropathological examination revealed severe AD pathology (Braak Amyloid stage C, Consortium to Establish a Registry for Alzheimer's Disease [CERAD] stage C, Thal phase 5, and Braak AT8 stage IV) along with Lewy pathology and argyrophilic grains, predominantly in the amygdala. Furthermore, no transactivation response DNA-binding protein of 43 kDa (TDP-43) pathology was observed. Our results suggest that a combination of these pathologies causes bvFTD-like cognitive and behavioral symptoms. This case is very insightful when considering the lesions responsible for the psychiatric symptoms characteristic of bvFTD.

Electroacupuncture Enhances Cognition by Promoting Brain Glucose Metabolism and Inhibiting Inflammation in the APP/PS1 Mouse Model of Alzheimer's Disease: A Pilot Study

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease, yet there is no effective treatment. Electroacupuncture (EA) is a complementary alternative medicine approach. In clinical and animal studies, EA promotes cognition in AD and vascular dementia. It has been previously reported that cognitive decline in AD might be closely related to reduced glucose intake in the brain. It is worth mentioning that the regions of glucose hypometabolism are usually found to be associated with neuroinflammation.

OBJECTIVE

This study is to explore whether the protective mechanism of EA on cognition is related to the regulation of glucose metabolism and neuroinflammation.

METHODS

APP/PS1 mice were randomly divided into AD group and the treatment (AD + EA) group. In the AD + EA group, EA was applied on Baihui (GV20) and Yintang (GV29) for 20 min and then pricked at Shuigou (GV26), once every alternate day for 4 weeks. Morris water maze (MWM) tests were performed to evaluate the effects of EA treatment on cognitive functions. 18F-FDG PET, immunofluorescence, and western blot were used to examine the mechanisms underlying EA effects.

RESULTS

From MWM tests, EA treatment significantly improved cognition of APP/PS1 mice. From the 18F-FDG PET, the levels of uptake rate of glucose in frontal lobe were higher than the AD group after EA. From immunofluorescence and western blot, amyloid-β (Aβ) and neuroinflammation were reduced after EA.

CONCLUSION

These results suggest that EA may prevent cognitive decline in AD mouse models by enhancing glucose metabolism and inhibiting inflammation-mediated Aβ deposition in the frontal lobe.

Impairment of episodic memory in genetic frontotemporal dementia: A GENFI study

INTRODUCTION

We aimed to assess episodic memory in genetic frontotemporal dementia (FTD) with the Free and Cued Selective Reminding Test (FCSRT).

METHODS

The FCSRT was administered in 417 presymptomatic and symptomatic mutation carriers (181 chromosome 9 open reading frame 72 [C9orf72], 163 progranulin [GRN], and 73 microtubule-associated protein tau [MAPT]) and 290 controls. Group differences and correlations with other neuropsychological tests were examined. We performed voxel-based morphometry to investigate the underlying neural substrates of the FCSRT.

RESULTS

All symptomatic mutation carrier groups and presymptomatic MAPT mutation carriers performed significantly worse on all FCSRT scores compared to controls. In the presymptomatic C9orf72 group, deficits were found on all scores except for the delayed total recall task, while no deficits were found in presymptomatic GRN mutation carriers. Performance on the FCSRT correlated with executive function, particularly in C9orf72 mutation carriers, but also with memory and naming tasks in the MAPT group. FCSRT performance also correlated with gray matter volumes of frontal, temporal, and subcortical regions in C9orf72 and GRN, but mainly temporal areas in MAPT mutation carriers.

DISCUSSION

The FCSRT detects presymptomatic deficits in C9orf72- and MAPT-associated FTD and provides important insight into the underlying cause of memory impairment in different forms of FTD.

Alzheimer's Disease or Behavioral Variant Frontotemporal Dementia? Review of Key Points Toward an Accurate Clinical and Neuropsychological Diagnosis

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are the most common neurodegenerative early-onset dementias. Despite the fact that both conditions have a very distinctive clinical pattern, they present with an overlap in their cognitive and behavioral features that may lead to misdiagnosis or delay in diagnosis. The current review intends to summarize briefly the main differences at the clinical, neuropsychological, and behavioral levels, in an attempt to suggest which aspects would facilitate an adequate diagnosis in a clinical setting, especially in Latin American and low- and middle-income countries, where the resources needed for a differential diagnosis (such as MRI or biomarkers) are not always available. A timely diagnosis of AD and FTD have significant implications for the medical management and quality of life of patients and careers.

Characteristics and progression of patients with frontotemporal dementia in a regional memory clinic network

Background

Due to heterogeneous clinical presentation, difficult differential diagnosis with Alzheimer’s disease (AD) and psychiatric disorders, and evolving clinical criteria, the epidemiology and natural history of frontotemporal lobar degeneration (FTD) remain elusive. In order to better characterize FTD patients, we relied on the database of a regional memory clinic network with standardized diagnostic procedures and chose AD patients as a comparator.

Methods

Patients that were first referred to our network between January 2010 and December 2016 and whose last clinical diagnosis was degenerative or vascular dementia were included. Comparisons were conducted between FTD and AD as well as between the different FTD syndromes, divided into language variants (lvFTD), behavioral variant (bvFTD), and FTD with primarily motor symptoms (mFTD). Cognitive progression was estimated with the yearly decline in Mini Mental State Examination (MMSE).

Results

Among the patients that were referred to our network in the 6-year time span, 690 were ultimately diagnosed with FTD and 18,831 with AD. Patients with FTD syndromes represented 2.6% of all-cause dementias. The age-standardized incidence was 2.90 per 100,000 person-year and incidence peaked between 75 and 79 years. Compared to AD, patients with FTD syndromes had a longer referral delay and delay to diagnosis. Patients with FTD syndromes had a higher MMSE score than AD at first referral while their progression was similar. mFTD patients had the shortest survival while survival in bvFTD, lvFTD, and AD did not significantly differ. FTD patients, especially those with the behavioral variant, received more antidepressants, anxiolytics, and antipsychotics than AD patients.

Conclusions

FTD syndromes differ with AD in characteristics at baseline, progression rate, and treatment. Despite a broad use of the new diagnostic criteria in an organized memory clinic network, FTD syndromes are longer to diagnose and account for a low proportion of dementia cases, suggesting persistent underdiagnosis. Congruent with recent publications, the late peak of incidence warns against considering FTD as being exclusively a young-onset dementia.

Scene construction impairments in frontotemporal dementia: Evidence for a primary hippocampal contribution

The capacity to generate naturalistic three-dimensional and spatially coherent representations of the world, i.e., scene construction, is posited to lie at the heart of a wide range of complex cognitive endeavours. Clinical populations with selective damage to key nodes of a putative scene construction network of the brain have provided important insights regarding the contribution of medial temporal and prefrontal regions in this regard. Here, we explored the capacity for atemporal scene construction, and its associated neural substrates, in the behavioural-variant of frontotemporal dementia (bvFTD); a neurodegenerative brain disorder in which atrophy systematically erodes medial and lateral prefrontal cortices with variable medial temporal lobe involvement. Nineteen bvFTD patients were compared to 18 typical Alzheimer's Disease (AD), and 25 healthy older Control participants on a scene construction task. Relative to Controls, both patient groups displayed marked impairments in generating contextually detailed and spatially coherent scenes, with bvFTD indistinguishable from AD patients across the majority of task metrics. Voxel-based morphometry, based on structural brain MRI, revealed divergent neural substrates of scene construction performance in each patient group. Despite widespread medial and lateral prefrontal atrophy, the capacity to generate richly detailed and spatially coherent scenes in bvFTD was found to rely predominantly upon the integrity of right medial temporal structures, including the hippocampus and parahippocampal gyrus. Scene construction impairments in AD, by contrast, hinged upon the integrity of posterior parietal brain regions. Our findings in bvFTD resonate with a large body of work implicating the right hippocampus in the construction of spatially integrated scene imagery. How these impairments relate to changes in autobiographical memory and prospection in bvFTD will be an important question for future studies to address.

Structural Anatomical Investigation of Long-Term Memory Deficit in Behavioral Frontotemporal Dementia

Although a growing body of work has shown that behavioral variant frontotemporal dementia (bvFTD) could present with severe amnesia in approximately half of cases, memory assessment is currently the clinical standard to distinguish bvFTD from Alzheimer's disease (AD). Thus, the concept of "relatively preserved episodic memory" in bvFTD remains the basis of its clinical distinction from AD and a criterion for bvFTD's diagnosis. This view is supported by the idea that bvFTD is not characterized by genuine amnesia and hippocampal degeneration, by contrast to AD. In this multicenter study, we aimed to investigate the neural correlates of memory performance in bvFTD as assessed by the Free and Cued Selective Reminding Test (FCSRT). Imaging explorations followed a two-step procedure, first relying on a visual rating of atrophy of 35 bvFTD and 34 AD patients' MRI, contrasted with 29 controls; and then using voxel-based morphometry (VBM) in a subset of bvFTD patients. Results showed that 43% of bvFTD patients presented with a genuine amnesia. Data-driven analysis on visual rating data showed that, in bvFTD, memory recall & storage performances were significantly predicted by atrophy in rostral prefrontal and hippocampal/perihippocampal regions, similar to mild AD. VBM results in bvFTD (pFWE<0.05) showed similar prefrontal and hippocampal regions in addition to striatal and lateral temporal involvement. Our findings showed the involvement of prefrontal as well as medial/lateral temporal atrophy in memory deficits of bvFTD patients. This contradicts the common view that only frontal deficits explain memory impairment in this disease and plead for an updated view on memory dysfunctions in bvFTD.

Structural and functional papez circuit integrity in amyotrophic lateral sclerosis

Cognitive impairment in amyotrophic lateral sclerosis (ALS) is heterogeneous but now recognized as a feature in non-demented patients and no longer exclusively attributed to executive dysfunction. However, despite common reports of temporal lobe changes and memory deficits in ALS, episodic memory has been less explored. In the current study, we examined how the Papez circuit-a circuit known to participate in memory processes-is structurally and functionally affected in ALS patients (n = 20) compared with healthy controls (n = 15), and whether these changes correlated with a commonly used clinical measure of episodic memory. Our multimodal MRI approach (cortical volume, voxel-based morphometry, diffusion tensor imaging and resting state functional magnetic resonance) showed reduced gray matter in left hippocampus, left entorhinal cortex and right posterior cingulate as well as increased white matter fractional anisotropy and decreased mean diffusivity in the left cingulum bundle (hippocampal part) of ALS patients compared with controls. Interestingly, thalamus, mammillary bodies and fornix were preserved. Finally, we report a decreased functional connectivity in ALS patients in bilateral hippocampus, bilateral anterior and posterior parahippocampal gyrus and posterior cingulate. The results revealed that ALS patients showed statistically significant structural changes, but more important, widespread prominent functional connectivity abnormalities across the regions comprising the Papez circuit. The decreased functional connectivity found in the Papez network may suggest these changes could be used to assess risk or assist early detection or development of memory symptoms in ALS patients even before structural changes are established.

The CERAD Neuropsychological Assessment Battery Is Sensitive to Alcohol-Related Cognitive Deficiencies in Elderly Patients: A Retrospective Matched Case-Control Study

OBJECTIVES

Adverse effects of heavy drinking on cognition have frequently been reported. In the present study, we systematically examined for the first time whether clinical neuropsychological assessments may be sensitive to alcohol abuse in elderly patients with suspected minor neurocognitive disorder.

METHODS

A total of 144 elderly with and without alcohol abuse (each group n=72; mean age 66.7 years) were selected from a patient pool of n=738 by applying propensity score matching (a statistical method allowing to match participants in experimental and control group by balancing various covariates to reduce selection bias). Accordingly, study groups were almost perfectly matched regarding age, education, gender, and Mini Mental State Examination score. Neuropsychological performance was measured using the CERAD (Consortium to Establish a Registry for Alzheimer's Disease). Classification analyses (i.e., decision tree and boosted trees models) were conducted to examine whether CERAD variables or total score contributed to group classification.

RESULTS

Decision tree models disclosed that groups could be reliably classified based on the CERAD variables "Word List Discriminability" (tapping verbal recognition memory, 64% classification accuracy) and "Trail Making Test A" (measuring visuo-motor speed, 59% classification accuracy). Boosted tree analyses further indicated the sensitivity of "Word List Recall" (measuring free verbal recall) for discriminating elderly with versus without a history of alcohol abuse.

CONCLUSIONS

This indicates that specific CERAD variables seem to be sensitive to alcohol-related cognitive dysfunctions in elderly patients with suspected minor neurocognitive disorder. (JINS, 2018, 24, 360-371).

Episodic Memory Dysfunction in Behavioral Variant Frontotemporal Dementia: A Clinical And FDG-PET Study

BACKGROUND

Episodic memory disturbance is still considered as an exclusion criterion for behavioral variant frontotemporal dementia (bvFTD), but growing evidence suggests that memory can be impaired.

OBJECTIVE

Our main purposes were to assess episodic memory in a group of bvFTD patients comparatively with Alzheimer's disease (AD) patients, and analyze the relationship between episodic memory and brain metabolism measured using positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG-PET).

METHODS

Twenty-six bvFTD, 29 AD, and 24 healthy controls were included. Episodic memory was assessed by the Free and Cued Selective Reminding Test (FCSRT), which controls for effective encoding and measures memory consolidation processing. All participants underwent FDG-PET brain scans to provide data for voxel-based brain mapping analysis.

RESULTS

Half of bvFTD patients had a deficit of total, free delayed, and total free delayed recall as severe as AD patients (amnestic-FTD). The other half had FCSRT scores similar to controls (non-amnestic-FTD). Imaging analyses revealed that amnestic-FTD showed bilateral lower metabolism than non-amnestic-FTD in anterior parahippocampal and inferior temporal gyri. Additionally, FCSRT total and total delayed scores were inversely correlated with parahippocampal metabolism in both bvFTD and AD. Besides, bvFTD showed an inverse association among FCSRT and inferior temporal metabolism.

CONCLUSIONS

Our findings support that bvFTD could present a genuine amnesia affecting storage and consolidation abilities, which involves structures implicated in the Papez circuit, as occurs in AD, and also inferior temporal regions. These results contribute to understanding the mechanisms underpinning memory dysfunction in bvFTD, and may be relevant to further revisions of the current diagnostic criteria.

Alzheimer's Disease Diagnosis Relies on a Twofold Clinical-Biological Algorithm: Three Memory Clinic Case Reports

The International Working Group recently provided revised criteria of Alzheimer's disease (AD) proposing that the diagnosis of typical amnesic AD should be established by a clinical-biological signature, defined by the phenotype of an "amnesic syndrome of the hippocampal type" (ASHT) combined with positive in vivo evidence of AD pathophysiology in the cerebrospinal fluid (CSF) or on amyloid PET imaging. The application and clinical value of this refined diagnostic algorithm, initially intended for research purposes, is explored in three memory clinic cases presenting with different cognitive profiles including an ASHT, hippocampal atrophy, and CSF AD-biomarker data. The case reports highlight that the isolated occurrence of one of the two proposed AD criteria, ASHT or positive pathophysiological markers, does not provide a reliable diagnosis of typical AD. It is proposed that the twofold diagnostic IWG algorithm can be applied and operationalized in memory clinic settings to improve the diagnostic accuracy of typical amnesic AD in clinical practice.