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Brown A, Salo SK, Savage G. Frontal variant Alzheimer's disease: A systematic narrative synthesis. Cortex 2023; 166:121-153. [PMID: 37356113 DOI: 10.1016/j.cortex.2023.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 01/03/2023] [Accepted: 05/22/2023] [Indexed: 06/27/2023]
Abstract
BACKGROUND Frontal variant Alzheimer's disease (fvAD) is considered a rare form of Alzheimer's disease (AD) which may be misdiagnosed as behavioural variant frontotemporal dementia (bvFTD). The literature has tended to conflate behavioural and executive dysfunction in fvAD cohorts and uses both AD diagnostic criteria and bvFTD diagnostic criteria to classify fvAD cohorts. The primary aim of this narrative synthesis was to summarise neuropsychological findings in fvAD cohorts in the context of established AD pathology. METHODS EMBASE, PsycINFO, PROQUEST and MEDLINE databases were searched for studies eligible for inclusion. Studies with both neuropsychological and biomarker evidence were included in the final narrative synthesis. RESULTS Ten studies were reviewed, including samples totalling 342 fvAD participants, 178 typical AD participants and 250 bvFTD participants. The review revealed areas worthy of further investigation that may aid differential diagnosis, including the degree of executive dysfunction in fvAD cohorts relative to bvFTD cohorts, the onset of behavioural and cognitive symptomatology, and similarities between fvAD and typical AD cognitive profiles. CONCLUSION There was insufficient neuropsychological evidence to clearly differentiate fvAD and bvFTD cognitive phenotypes, however, the review has highlighted distinctive features of the two disorders that may guide differential diagnosis in future research. Moreover, the review has highlighted issues involving disparate diagnostic criteria used to classify fvAD cohorts, contributing to variation in findings.
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Affiliation(s)
- Andrea Brown
- School of Psychological Sciences, Macquarie University, Sydney, Australia
| | - Sarah K Salo
- Department of Psychology, Swansea University, Swansea, UK; School of Psychology, University of Plymouth, Plymouth, UK
| | - Greg Savage
- School of Psychological Sciences, Macquarie University, Sydney, Australia.
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Polsinelli AJ, Apostolova LG. Atypical Alzheimer Disease Variants. Continuum (Minneap Minn) 2022; 28:676-701. [PMID: 35678398 PMCID: PMC10028410 DOI: 10.1212/con.0000000000001082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE OF REVIEW This article discusses the clinical, neuroimaging, and biomarker profiles of sporadic atypical Alzheimer disease (AD) variants, including early-onset AD, posterior cortical atrophy, logopenic variant primary progressive aphasia, dysexecutive variant and behavioral variant AD, and corticobasal syndrome. RECENT FINDINGS Significant advances are being made in the recognition and characterization of the syndromically diverse AD variants. These variants are identified by the predominant cognitive and clinical features: early-onset amnestic syndrome, aphasia, visuospatial impairments, dysexecutive and behavioral disturbance, or motor symptoms. Although understanding of regional susceptibility to disease remains in its infancy, visualizing amyloid and tau pathology in vivo and CSF examination of amyloid-β and tau proteins are particularly useful in atypical AD, which can be otherwise prone to misdiagnosis. Large-scale research efforts, such as LEADS (the Longitudinal Early-Onset Alzheimer Disease Study), are currently ongoing and will continue to shed light on our understanding of these diverse presentations. SUMMARY Understanding the clinical, neuroimaging, and biomarker profiles of the heterogeneous group of atypical AD syndromes improves diagnostic accuracy in patients who are at increased risk of misdiagnosis. Earlier accurate identification facilitates access to important interventions, social services and disability assistance, and crucial patient and family education.
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Jenkins LM, Wang L, Rosen H, Weintraub S. A transdiagnostic review of neuroimaging studies of apathy and disinhibition in dementia. Brain 2022; 145:1886-1905. [PMID: 35388419 PMCID: PMC9630876 DOI: 10.1093/brain/awac133] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/18/2022] [Accepted: 03/13/2022] [Indexed: 11/12/2022] Open
Abstract
Apathy and disinhibition are common and highly distressing neuropsychiatric symptoms associated with negative outcomes in persons with dementia. This paper is a critical review of functional and structural neuroimaging studies of these symptoms transdiagnostically in dementia of the Alzheimer type, which is characterized by prominent amnesia early in the disease course, and behavioural variant frontotemporal dementia, characterized by early social-comportmental deficits. We describe the prevalence and clinical correlates of these symptoms and describe methodological issues, including difficulties with symptom definition and different measurement instruments. We highlight the heterogeneity of findings, noting however, a striking similarity of the set of brain regions implicated across clinical diagnoses and symptoms. These regions involve several key nodes of the salience network, and we describe the functions and anatomical connectivity of these brain areas, as well as present a new theoretical account of disinhibition in dementia. Future avenues for research are discussed, including the importance of transdiagnostic studies, measuring subdomains of apathy and disinhibition, and examining different units of analysis for deepening our understanding of the networks and mechanisms underlying these extremely distressing symptoms.
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Affiliation(s)
- Lisanne M Jenkins
- Correspondence to: Lisanne Jenkins 710 N Lakeshore Drive, Suite 1315 Chicago, IL 60611, USA E-mail:
| | - Lei Wang
- Department of Psychiatry and Behavioral Health, Wexner Medical Center, Ohio State University, Columbus, OH 43210, USA
| | - Howie Rosen
- Weill Institute for Neurosciences, School of Medicine, University of California, San Francisco, CA, USA 94158
| | - Sandra Weintraub
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA,Mesulam Center for Cognitive Neurology and Alzheimer’s Disease, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA 60611
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Ossenkoppele R, Singleton EH, Groot C, Dijkstra AA, Eikelboom WS, Seeley WW, Miller B, Laforce RJ, Scheltens P, Papma JM, Rabinovici GD, Pijnenburg YAL. Research Criteria for the Behavioral Variant of Alzheimer Disease: A Systematic Review and Meta-analysis. JAMA Neurol 2021; 79:48-60. [PMID: 34870696 PMCID: PMC8649917 DOI: 10.1001/jamaneurol.2021.4417] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Importance The behavioral variant of Alzheimer disease (bvAD) is characterized by early and predominant behavioral deficits caused by AD pathology. This AD phenotype is insufficiently understood and lacks standardized clinical criteria, limiting reliability and reproducibility of diagnosis and scientific reporting. Objective To perform a systematic review and meta-analysis of the bvAD literature and use the outcomes to propose research criteria for this syndrome. Data Sources A systematic literature search in PubMed/MEDLINE and Web of Science databases (from inception through April 7, 2021) was performed in duplicate. Study Selection Studies reporting on behavioral, neuropsychological, or neuroimaging features in bvAD and, when available, providing comparisons with typical amnestic-predominant AD (tAD) or behavioral variant frontotemporal dementia (bvFTD). Data Extraction and Synthesis This analysis involved random-effects meta-analyses on group-level study results of clinical data and systematic review of the neuroimaging literature. The study was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Main Outcomes and Measures Behavioral symptoms (neuropsychiatric symptoms and bvFTD core clinical criteria), cognitive function (global cognition, episodic memory, and executive functioning), and neuroimaging features (structural magnetic resonance imaging, [18F]fluorodeoxyglucose-positron emission tomography, perfusion single-photon emission computed tomography, amyloid positron emission tomography, and tau positron emission tomography). Results The search led to the assessment of 83 studies, including 13 suitable for meta-analysis. Data were collected for 591 patients with bvAD. There was moderate to substantial heterogeneity and moderate risk of bias across studies. Cases with bvAD showed more severe behavioral symptoms than tAD (standardized mean difference [SMD], 1.16 [95% CI, 0.74-1.59]; P < .001) and a trend toward less severe behavioral symptoms compared with bvFTD (SMD, -0.22 [95% CI, -0.47 to 0.04]; P = .10). Meta-analyses of cognitive data indicated worse executive performance in bvAD vs tAD (SMD, -1.03 [95% CI, -1.74 to -0.32]; P = .008) but not compared with bvFTD (SMD, -0.61 [95% CI, -1.75 to 0.53]; P = .29). Cases with bvAD showed a nonsignificant difference of worse memory performance compared with bvFTD (SMD, -1.31 [95% CI, -2.75 to 0.14]; P = .08) but did not differ from tAD (SMD, 0.43 [95% CI, -0.46 to 1.33]; P = .34). The neuroimaging literature revealed 2 distinct bvAD neuroimaging phenotypes: an AD-like pattern with relative frontal sparing and a relatively more bvFTD-like pattern characterized by additional anterior involvement, with the AD-like pattern being more prevalent. Conclusions and Relevance These data indicate that bvAD is clinically most similar to bvFTD, while it shares most pathophysiological features with tAD. Based on these insights, we propose research criteria for bvAD aimed at improving the consistency and reliability of future research and aiding the clinical assessment of this AD phenotype.
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Affiliation(s)
- Rik Ossenkoppele
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands.,Lund University, Clinical Memory Research Unit, Lund, Sweden
| | - Ellen H Singleton
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Colin Groot
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Anke A Dijkstra
- Department of Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centre, Location VUMC, Amsterdam, the Netherlands
| | - Willem S Eikelboom
- Department of Neurology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - William W Seeley
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco
| | - Bruce Miller
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco
| | - Robert Jr Laforce
- Clinique Interdisciplinaire de Mémoire, Centre Hospitalier Universitaire de Québec, Québec, Canada
| | - Philip Scheltens
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Janne M Papma
- Department of Neurology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Gil D Rabinovici
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, San Francisco.,Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco.,Associate Editor, JAMA Neurology
| | - Yolande A L Pijnenburg
- Alzheimer Center Amsterdam, Department of Neurology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
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Csincsik L, Quinn N, Yong KXX, Crutch SJ, Peto T, Lengyel I. Retinal phenotyping of variants of Alzheimer's disease using ultra-widefield retinal images. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2021; 13:e12232. [PMID: 34458553 PMCID: PMC8377778 DOI: 10.1002/dad2.12232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Posterior cortical atrophy (PCA) is the most common atypical variant of Alzheimer's disease (AD). Changes associated with PCA in the brain affect the visual cortex, but little is known about retinal changes in PCA. In this study, we explored retinal phenotypic variations in typical AD (tAD) and PCA. METHODS Retinal phenotyping was carried out on ultra-widefield (UWF) images of 69 control, 24 tAD, and 25 PCA participants. RESULTS Individuals with tAD (odds ratio [OR] = 2.76 [confidence interval (CI):1.24 to 6.10], P = .012) and PCA (OR = 3.40 [CI:1.25 to 9.22], P = .016) were more likely phenotyped as hard drusen. tAD (OR = 0.34 [CI:0.12 to 0.92], P = .035) were less likely to have soft drusen compared to control. Almost 3-fold increase in reticular pseudodrusen formation in tAD (OR = 2.93 [CI:1.10 to 7.76], P = .030) compared to control was estimated. DISCUSSION Studying the peripheral retina may contribute to a better understanding of differences in retinal phenotypes of different AD variants.
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Affiliation(s)
- Lajos Csincsik
- Wellcome‐Wolfson Institute for Experimental MedicineQueen's University BelfastBelfastUK
| | - Nicola Quinn
- Centre for Public HealthQueen's University BelfastBelfastUK
| | - Keir X. X. Yong
- Dementia Research CentreUCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Sebastian J. Crutch
- Dementia Research CentreUCL Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Tunde Peto
- Centre for Public HealthQueen's University BelfastBelfastUK
| | - Imre Lengyel
- Wellcome‐Wolfson Institute for Experimental MedicineQueen's University BelfastBelfastUK
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