1
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Verovnik B, Khachatryan E, Šuput D, Van Hulle MM. Effects of risk factors on longitudinal changes in brain structure and function in the progression of AD. Alzheimers Dement 2023; 19:2666-2676. [PMID: 36807765 DOI: 10.1002/alz.12991] [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: 10/21/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 02/20/2023]
Abstract
INTRODUCTION Past research on Alzheimer's disease (AD) has focused on biomarkers, cognition, and neuroimaging as primary predictors of its progression, albeit additional ones have recently gained attention. When turning to the prediction of the progression from one stage to another, one could benefit from the joint assessment of imaging-based biomarkers and risk/protective factors. METHODS We included 86 studies that fulfilled our inclusion criteria. RESULTS Our review summarizes and discusses the results of 30 years of longitudinal research on brain changes assessed with neuroimaging and the risk/protective factors and their effect on AD progression. We group results into four sections: genetic, demographic, cognitive and cardiovascular, and lifestyle factors. DISCUSSION Given the complex nature of AD, including risk factors could prove invaluable for a better understanding of AD progression. Some of these risk factors are modifiable and could be targeted by potential future treatments.
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Affiliation(s)
- Barbara Verovnik
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Elvira Khachatryan
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Dušan Šuput
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Center for Clinical Physiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Marc M Van Hulle
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium
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2
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Jensen DEA, Leoni V, Klein-Flügge MC, Ebmeier KP, Suri S. Associations of dietary markers with brain volume and connectivity: A systematic review of MRI studies. Ageing Res Rev 2021; 70:101360. [PMID: 33991658 DOI: 10.1016/j.arr.2021.101360] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/22/2021] [Accepted: 05/08/2021] [Indexed: 11/20/2022]
Abstract
The high prevalence of unhealthy dietary patterns and related brain disorders, such as dementia, emphasizes the importance of research that examines the effect of dietary factors on brain health. Identifying markers of brain health, such as volume and connectivity, that relate to diet is an important first step towards understanding the lifestyle determinants of healthy brain ageing. We conducted a systematic review of 52 studies (total n = 21,221 healthy participants aged 26-80 years, 55 % female) that assessed with a range of MRI measurements, which brain areas, connections, and cerebrovascular factors were associated with dietary markers. We report associations between regional brain measures and dietary health. Collectively, lower diet quality was related to reduced brain volume and connectivity, especially in white and grey matter of the frontal, temporal and parietal lobe, cingulate, entorhinal cortex and the hippocampus. Associations were also observed in connecting fibre pathways and in particular the default-mode, sensorimotor and attention networks. However, there were also some inconsistencies in research methods and findings. We recommend that future research use more comprehensive and consistent dietary measures, more representative samples, and examine the role of key subcortical regions previously highlighted in relevant animal work.
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Affiliation(s)
- Daria E A Jensen
- Department of Psychiatry, University of Oxford, OX3 7JX, UK; Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, University of Oxford, OX37JX, UK.
| | - Virginia Leoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy
| | - Miriam C Klein-Flügge
- Department of Experimental Psychology, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Tinsley building, OX1 3SR, UK
| | | | - Sana Suri
- Department of Psychiatry, University of Oxford, OX3 7JX, UK; Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, University of Oxford, OX37JX, UK
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3
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Alateeq K, Walsh EI, Cherbuin N. Higher Blood Pressure is Associated with Greater White Matter Lesions and Brain Atrophy: A Systematic Review with Meta-Analysis. J Clin Med 2021; 10:637. [PMID: 33562359 PMCID: PMC7915964 DOI: 10.3390/jcm10040637] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND To summarise and quantify the evidence on the association between Blood pressure (BP), white matter lesions (WMLs), and brain volumes. METHOD Electronic databases PubMed, Scopus, and Clarivate were searched in February 2020 using an established methodology and pre-determined search terms. Studies were eligible for inclusion if they reported on the association between BP and WMLs or brain volume in cognitively healthy individuals, while adjusting for age and intra-cranial volume. RESULTS Searches yielded 7509 articles, of which 52 (26 longitudinal and 33 cross-sectional), were eligible and had a combined sample size of 343,794 individuals. Analyses found that 93.7% of studies reported that higher BP was associated with poorer cerebral health (higher WMLs and lower brain volumes). Meta-analysis of compatible results indicated a dose-dependent relationship with every one standard deviation increase in systolic BP (SBP) above 120 mmHg being associated with a 11.2% (95% CI 2.3, 19.9, p = 0.0128) increase in WMLs and -0.13% (95% CI -0.25, -0.023, p = 0.0183) smaller hippocampal volume. CONCLUSION The association between BP and brain volumes appears across the full range of BP measurements and is not limited to hypertensive individuals. Higher BP in community-residing individuals is associated with poorer cerebral health.
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Affiliation(s)
- Khawlah Alateeq
- Centre for Research on Ageing, Health and Wellbeing, The Australian National University, Canberra, ACT 2601, Australia; (E.I.W.); (N.C.)
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4
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Malykhin NV, Travis S, Fujiwara E, Huang Y, Camicioli R, Olsen F. The associations of the
BDNF
and
APOE
polymorphisms, hippocampal subfield volumes, and episodic memory performance across the lifespan. Hippocampus 2020; 30:1081-1097. [DOI: 10.1002/hipo.23217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 03/23/2020] [Accepted: 04/25/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Nikolai V. Malykhin
- Neuroscience and Mental Health Institute University of Alberta Edmonton Alberta Canada
- Department of Biomedical Engineering University of Alberta Edmonton Alberta Canada
- Department of Psychiatry University of Alberta Edmonton Alberta Canada
| | - Scott Travis
- Neuroscience and Mental Health Institute University of Alberta Edmonton Alberta Canada
| | - Esther Fujiwara
- Neuroscience and Mental Health Institute University of Alberta Edmonton Alberta Canada
- Department of Psychiatry University of Alberta Edmonton Alberta Canada
| | - Yushan Huang
- Department of Biomedical Engineering University of Alberta Edmonton Alberta Canada
| | | | - Fraser Olsen
- Department of Biomedical Engineering University of Alberta Edmonton Alberta Canada
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5
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Nadkarni NK, Tudorascu D, Campbell E, Snitz BE, Cohen AD, Halligan E, Mathis CA, Aizenstein HJ, Klunk WE. Association Between Amyloid-β, Small-vessel Disease, and Neurodegeneration Biomarker Positivity, and Progression to Mild Cognitive Impairment in Cognitively Normal Individuals. J Gerontol A Biol Sci Med Sci 2020; 74:1753-1760. [PMID: 30957843 DOI: 10.1093/gerona/glz088] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND We estimated the prevalence and incidence of amyloid-β deposition (A), small-vessel disease (V), and neurodegeneration (N) biomarker positivity in community-dwelling cognitively normal individuals (CN). We determined the longitudinal association between the respective biomarker indices with progression to all-cause mild cognitive impairment (MCI) and its amnestic and nonamnestic subtypes. METHODS CN participants, recruited by advertising, underwent brain [C-11]Pittsburgh Compound-B (PiB)-positron emission tomography (PET), magnetic resonance imaging, and [F-18]fluoro-2-deoxy-glucose (FDG)-PET, and were designated as having high or low amyloid-β (A+/A-), greater or lower white matter hyperintensities burden (V+/V-) and diminished or normal cortical glucose metabolism (N+/N-). MCI was adjudicated using clinical assessments. We examined the association between A, V, and N biomarker positivity at study baseline and endpoint, with progression to MCI using linear regression, Cox proportional hazards and Kaplan-Meier analyses adjusted for age and APOE-ε4 carrier status. RESULTS In 98 CN individuals (average age 74 years, 65% female), A+, V+, and N+ prevalence was 26%, 33%, and 8%, respectively. At study endpoint (median: 5.5 years), an A+, but not a V+ or N+ scan, was associated with higher odds of all-cause MCI (Chi-square = 3.9, p = .048, odds ratio, 95% confidence interval = 2.6 [1.01-6.8]). Baseline A+, V+, or N+ were not associated with all-cause MCI, however, baseline A+ (p = .018) and A+N+ (p = .049), and endpoint A+N+ (p = .025) were associated with time to progression to amnestic, not nonamnestic, MCI. CONCLUSION Longitudinal assessments clarify the association between amyloid-β and progression to all-cause MCI in CN individuals. The association between biomarker positivity indices of amyloid-β and neurodegeneration, and amnestic MCI reflects the underlying pathology involved in the progression to prodromal Alzheimer's disease.
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Affiliation(s)
- Neelesh K Nadkarni
- Division of Geriatric Medicine, Department of Medicine, University of Pittsburgh, Pennsylvania.,Department of Neurology, University of Pittsburgh, Pennsylvania
| | - Dana Tudorascu
- Division of General Internal Medicine, Department of Medicine, University of Pittsburgh, Pennsylvania.,Department of Biostatistics, University of Pittsburgh, Pennsylvania.,Department of Psychiatry, University of Pittsburgh, Pennsylvania
| | | | - Beth E Snitz
- Department of Neurology, University of Pittsburgh, Pennsylvania
| | - Annie D Cohen
- Department of Psychiatry, University of Pittsburgh, Pennsylvania
| | - Edye Halligan
- Department of Psychiatry, University of Pittsburgh, Pennsylvania
| | | | | | - William E Klunk
- Department of Neurology, University of Pittsburgh, Pennsylvania.,Department of Psychiatry, University of Pittsburgh, Pennsylvania
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6
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Zhang L, Mak E, Reilhac A, Shim HY, Ng KK, Ong MQW, Ji F, Chong EJY, Xu X, Wong ZX, Stephenson MC, Venketasubramanian N, Tan BY, O'Brien JT, Zhou JH, Chen CLH. Longitudinal trajectory of Amyloid-related hippocampal subfield atrophy in nondemented elderly. Hum Brain Mapp 2020; 41:2037-2047. [PMID: 31944479 PMCID: PMC7267893 DOI: 10.1002/hbm.24928] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 01/03/2020] [Accepted: 01/05/2020] [Indexed: 01/07/2023] Open
Abstract
Hippocampal atrophy and abnormal β‐Amyloid (Aβ) deposition are established markers of Alzheimer's disease (AD). Nonetheless, longitudinal trajectory of Aβ‐associated hippocampal subfield atrophy prior to dementia remains unclear. We hypothesized that elevated Aβ correlated with longitudinal subfield atrophy selectively in no cognitive impairment (NCI), spreading to other subfields in mild cognitive impairment (MCI). We analyzed data from two independent longitudinal cohorts of nondemented elderly, including global PET‐Aβ in AD‐vulnerable cortical regions and longitudinal subfield volumes quantified with a novel auto‐segmentation method (FreeSurfer v.6.0). Moreover, we investigated associations of Aβ‐related progressive subfield atrophy with memory decline. Across both datasets, we found a converging pattern that higher Aβ correlated with faster CA1 volume decline in NCI. This pattern spread to other hippocampal subfields in MCI group, correlating with memory decline. Our results for the first time suggest a longitudinal focal‐to‐widespread trajectory of Aβ‐associated hippocampal subfield atrophy over disease progression in nondemented elderly.
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Affiliation(s)
- Liwen Zhang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore.,Memory Ageing and Cognition Centre, National University Health System, Singapore, Singapore
| | - Elijah Mak
- Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
| | - Anthonin Reilhac
- Clinical Imaging Research Center, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore
| | - Hee Y Shim
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore
| | - Kwun K Ng
- Center for Sleep and Cognition, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore
| | - Marcus Q W Ong
- Center for Sleep and Cognition, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore
| | - Fang Ji
- Center for Sleep and Cognition, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore
| | - Eddie J Y Chong
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Memory Ageing and Cognition Centre, National University Health System, Singapore, Singapore
| | - Xin Xu
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Memory Ageing and Cognition Centre, National University Health System, Singapore, Singapore
| | - Zi X Wong
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Memory Ageing and Cognition Centre, National University Health System, Singapore, Singapore
| | - Mary C Stephenson
- Clinical Imaging Research Center, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore
| | | | - Boon Y Tan
- St. Luke's Hospital, Singapore, Singapore
| | - John T O'Brien
- Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
| | - Juan H Zhou
- Center for Sleep and Cognition, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Center for Cognitive Neuroscience, Neuroscience and Behavioural Disorders Program, Duke-National University of Singapore Medical School, Singapore.,Clinical Imaging Research Center, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore
| | - Christopher L H Chen
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Memory Ageing and Cognition Centre, National University Health System, Singapore, Singapore
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7
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van Leijsen EMC, Tay J, van Uden IWM, Kooijmans ECM, Bergkamp MI, van der Holst HM, Ghafoorian M, Platel B, Norris DG, Kessels RPC, Markus HS, Tuladhar AM, de Leeuw FE. Memory decline in elderly with cerebral small vessel disease explained by temporal interactions between white matter hyperintensities and hippocampal atrophy. Hippocampus 2018; 29:500-510. [PMID: 30307080 DOI: 10.1002/hipo.23039] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 09/07/2018] [Accepted: 09/29/2018] [Indexed: 11/11/2022]
Abstract
White matter hyperintensities (WMH) constitute the visible spectrum of cerebral small vessel disease (SVD) markers and are associated with cognitive decline, although they do not fully account for memory decline observed in individuals with SVD. We hypothesize that WMH might exert their effect on memory decline indirectly by affecting remote brain structures such as the hippocampus. We investigated the temporal interactions between WMH, hippocampal atrophy and memory decline in older adults with SVD. Five hundred and three participants of the RUNDMC study underwent neuroimaging and cognitive assessments up to 3 times over 8.7 years. We assessed WMH volumes semi-automatically and calculated hippocampal volumes (HV) using FreeSurfer. We used linear mixed effects models and causal mediation analyses to assess both interaction and mediation effects of hippocampal atrophy in the associations between WMH and memory decline, separately for working memory (WM) and episodic memory (EM). Linear mixed effect models revealed that the interaction between WMH and hippocampal volumes explained memory decline (WM: β = .067; 95%CI[.024-0.111]; p < .01; EM: β = .061; 95%CI[.025-.098]; p < .01), with better model fit when the WMH*HV interaction term was added to the model, for both WM (likelihood ratio test, χ2 [1] = 9.3, p < .01) and for EM (likelihood ratio test, χ2 [1] = 10.7, p < .01). Mediation models showed that both baseline WMH volume (β = -.170; p = .001) and hippocampal atrophy (β = 0.126; p = .009) were independently related to EM decline, but the effect of baseline WMH on EM decline was not mediated by hippocampal atrophy (p value indirect effect: 0.572). Memory decline in elderly with SVD was best explained by the interaction of WMH and hippocampal volumes. The relationship between WMH and memory was not causally mediated by hippocampal atrophy, suggesting that memory decline during aging is a heterogeneous condition in which different pathologies contribute to the memory decline observed in elderly with SVD.
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Affiliation(s)
- Esther M C van Leijsen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jonathan Tay
- Department of Clinical Neurosciences, Neurology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Ingeborg W M van Uden
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Eline C M Kooijmans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mayra I Bergkamp
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | | | - Mohsen Ghafoorian
- Radboud University Medical Centre, Diagnostic Image Analysis Group, Department of Radiology and Nuclear Medicine, Nijmegen, The Netherlands.,Radboud University, Institute for Computing and Information Sciences, Nijmegen, The Netherlands
| | - Bram Platel
- Radboud University Medical Centre, Diagnostic Image Analysis Group, Department of Radiology and Nuclear Medicine, Nijmegen, The Netherlands
| | - David G Norris
- Radboud University, Donders Institute for Brain Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany
| | - Roy P C Kessels
- Department of Medical Psychology, Radboud University Medical Centre, Radboud Alzheimer Centre, Nijmegen, The Netherlands.,Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognition, Nijmegen, The Netherlands
| | - Hugh S Markus
- Department of Clinical Neurosciences, Neurology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Anil M Tuladhar
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Frank-Erik de Leeuw
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Donders Center for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
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8
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Ten Kate M, Barkhof F, Boccardi M, Visser PJ, Jack CR, Lovblad KO, Frisoni GB, Scheltens P. Clinical validity of medial temporal atrophy as a biomarker for Alzheimer's disease in the context of a structured 5-phase development framework. Neurobiol Aging 2017; 52:167-182.e1. [PMID: 28317647 DOI: 10.1016/j.neurobiolaging.2016.05.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 05/01/2016] [Accepted: 05/10/2016] [Indexed: 01/18/2023]
Abstract
Research criteria for Alzheimer's disease recommend the use of biomarkers for diagnosis, but whether biomarkers improve the diagnosis in clinical routine has not been systematically assessed. The aim is to evaluate the evidence for use of medial temporal lobe atrophy (MTA) as a biomarker for Alzheimer's disease at the mild cognitive impairment stage in routine clinical practice, with an adapted version of the 5-phase oncology framework for biomarker development. A literature review on visual assessment of MTA and hippocampal volumetry was conducted with other biomarkers addressed in parallel reviews. Ample evidence is available for phase 1 (rationale for use) and phase 2 (discriminative ability between diseased and control subjects). Phase 3 (early detection ability) is partly achieved: most evidence is derived from research cohorts or clinical populations with short follow-up, but validation in clinical mild cognitive impairment cohorts is required. In phase 4, only the practical feasibility has been addressed for visual rating of MTA. The rest of phase 4 and phase 5 have not yet been addressed.
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Affiliation(s)
- Mara Ten Kate
- Department of Neurology, Alzheimer Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands.
| | - Frederik Barkhof
- Department of Radiology & Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands; European Society of Neuroradiology (ESNR); Institutes of Neurology and Healthcare Engineering, University College London, London, UK
| | - Marina Boccardi
- Laboratory of Alzheimer's Neuroimaging and Epidemiology (LANE), IRCCS S.Giovanni di Dio - Fatebenefratelli, Brescia, Italy; LANVIE (Laboratory of Neuroimaging of Aging) - Department of Psychiatry, University of Geneva, Geneva, Switzerland
| | - Pieter Jelle Visser
- Department of Neurology, Alzheimer Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands; Department of Psychiatry & Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | | | - Karl-Olof Lovblad
- Department of Neuroradiology, University Hospital of Geneva, Geneva, Switzerland
| | - Giovanni B Frisoni
- Institutes of Neurology and Healthcare Engineering, University College London, London, UK; Memory Clinic - Department of Internal Medicine, University Hospital of Geneva, Geneva, Switzerland
| | - Philip Scheltens
- Department of Neurology, Alzheimer Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands
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9
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Gerritsen L, Wang HX, Reynolds CA, Fratiglioni L, Gatz M, Pedersen NL. Influence of Negative Life Events and Widowhood on Risk for Dementia. Am J Geriatr Psychiatry 2017; 25:766-778. [PMID: 28433549 PMCID: PMC5474139 DOI: 10.1016/j.jagp.2017.02.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 12/19/2016] [Accepted: 02/09/2017] [Indexed: 01/25/2023]
Abstract
OBJECTIVE The aim of the current study was to examine the effect of negative life events and widowhood on the incidence of dementia. METHODS Data were from four Swedish longitudinal cohort studies with a total of nearly 2,000 participants and 8-25 years of follow-up. Seven stressful events were examined for which data were available in all cohorts. Clinical dementia diagnoses were made through medical and psychological examinations. Cox proportional hazards models were used to estimate the association between life events and dementia, adjusting for lifestyle and cardiovascular risk factors. RESULTS The experience of one stressful life event was not associated with dementia incidence, but two or more negative life events at baseline predicted higher risk for dementia (pooled HR: 2.00). This was most apparent for the incidence of vascular dementia (pooled HR: 3.60) but not for Alzheimer disease (pooled HR: 1.29). Moreover, persons who were widowed and had experienced one or more negative life events were found to have a threefold risk for dementia. CONCLUSION Widowhood augments the effect of negative life events on dementia incidence and negative life events specifically increase the risk for vascular dementia.
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Affiliation(s)
- Lotte Gerritsen
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Clinical Psychology, Utrecht University, Utrecht, The Netherlands.
| | - Hui-Xin Wang
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet-Stockholm University, Stockholm, Sweden
| | - Chandra A Reynolds
- Department of Psychology, University of California-Riverside, Riverside, CA
| | - Laura Fratiglioni
- Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet-Stockholm University, Stockholm, Sweden; Stockholm Gerontology Research Center, Stockholm, Sweden
| | - Margaret Gatz
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Psychology, University of Southern California, Los Angeles, CA
| | - Nancy L Pedersen
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Psychology, University of Southern California, Los Angeles, CA
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10
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Tai LM, Thomas R, Marottoli FM, Koster KP, Kanekiyo T, Morris AWJ, Bu G. The role of APOE in cerebrovascular dysfunction. Acta Neuropathol 2016; 131:709-23. [PMID: 26884068 DOI: 10.1007/s00401-016-1547-z] [Citation(s) in RCA: 139] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 02/10/2016] [Accepted: 02/10/2016] [Indexed: 11/30/2022]
Abstract
The ε4 allele of the apolipoprotein E gene (APOE4) is associated with cognitive decline during aging, is the greatest genetic risk factor for Alzheimer's disease and has links to other neurodegenerative conditions that affect cognition. Increasing evidence indicates that APOE genotypes differentially modulate the function of the cerebrovasculature (CV), with apoE and its receptors expressed by different cell types at the CV interface (astrocytes, pericytes, smooth muscle cells, brain endothelial cells). However, research on the role of apoE in CV dysfunction has not advanced as quickly as other apoE-modulated pathways. This review will assess what aspects of the CV are modulated by APOE genotypes during aging and under disease states, discuss potential mechanisms, and summarize the therapeutic significance of the topic. We propose that APOE4 induces CV dysfunction through direct signaling at the CV, and indirectly via modulation of peripheral and central pathways. Further, that APOE4 predisposes the CV to damage by, and exacerbates the effects of, additional risk factors (such as sex, hypertension, and diabetes). ApoE4-induced detrimental CV changes include reduced cerebral blood flow (CBF), modified neuron-CBF coupling, increased blood-brain barrier leakiness, cerebral amyloid angiopathy, hemorrhages and disrupted transport of nutrients and toxins. The apoE4-induced detrimental changes may be linked to pericyte migration/activation, astrocyte activation, smooth muscle cell damage, basement membrane degradation and alterations in brain endothelial cells.
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Affiliation(s)
- Leon M Tai
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S.Wood St., M/C 512, Chicago, IL, 60612, USA.
| | - Riya Thomas
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S.Wood St., M/C 512, Chicago, IL, 60612, USA
| | - Felecia M Marottoli
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S.Wood St., M/C 512, Chicago, IL, 60612, USA
| | - Kevin P Koster
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S.Wood St., M/C 512, Chicago, IL, 60612, USA
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Alan W J Morris
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S.Wood St., M/C 512, Chicago, IL, 60612, USA
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
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11
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Life-course blood pressure in relation to brain volumes. Alzheimers Dement 2016; 12:890-9. [PMID: 27139841 DOI: 10.1016/j.jalz.2016.03.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 03/14/2016] [Accepted: 03/24/2016] [Indexed: 11/21/2022]
Abstract
INTRODUCTION The impact of blood pressure on brain volumes may be time-dependent or pattern-dependent. METHODS Of 1678 participants from the Atherosclerosis Risk in Communities Neurocognitive Study, we quantified the association between measures and patterns of blood pressure over three time points (∼24 or ∼15 years prior and concurrent with neuroimaging) with late life brain volumes. RESULTS Higher diastolic blood pressure ∼24 years prior, higher systolic and pulse pressure ∼15 years prior, and consistently elevated or rising systolic blood pressure from ∼15 years prior to concurrent with neuroimaging, but not blood pressures measured concurrent with neuroimaging, were associated with smaller volumes. The pattern of hypertension ∼15 years prior and hypotension concurrent with neuroimaging was associated with smaller volumes in regions preferentially affected by Alzheimer's disease (e.g., hippocampus: -0.27 standard units, 95% CI: -0.51, -0.03). DISCUSSION Hypertension 15 to 24 years prior is relevant to current brain volumes. Hypertension followed by hypotension appears particularly detrimental.
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Ziegler G, Penny WD, Ridgway GR, Ourselin S, Friston KJ. Estimating anatomical trajectories with Bayesian mixed-effects modeling. Neuroimage 2015; 121:51-68. [PMID: 26190405 PMCID: PMC4607727 DOI: 10.1016/j.neuroimage.2015.06.094] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 03/04/2015] [Accepted: 06/30/2015] [Indexed: 01/29/2023] Open
Abstract
We introduce a mass-univariate framework for the analysis of whole-brain structural trajectories using longitudinal Voxel-Based Morphometry data and Bayesian inference. Our approach to developmental and aging longitudinal studies characterizes heterogeneous structural growth/decline between and within groups. In particular, we propose a probabilistic generative model that parameterizes individual and ensemble average changes in brain structure using linear mixed-effects models of age and subject-specific covariates. Model inversion uses Expectation Maximization (EM), while voxelwise (empirical) priors on the size of individual differences are estimated from the data. Bayesian inference on individual and group trajectories is realized using Posterior Probability Maps (PPM). In addition to parameter inference, the framework affords comparisons of models with varying combinations of model order for fixed and random effects using model evidence. We validate the model in simulations and real MRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) project. We further demonstrate how subject specific characteristics contribute to individual differences in longitudinal volume changes in healthy subjects, Mild Cognitive Impairment (MCI), and Alzheimer's Disease (AD).
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Affiliation(s)
- G Ziegler
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK; Dementia Research Centre, Institute of Neurology, University College London, UK.
| | - W D Penny
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK
| | - G R Ridgway
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK; FMRIB, Nuffield Dept. of Clinical Neurosciences, University of Oxford, UK
| | - S Ourselin
- Dementia Research Centre, Institute of Neurology, University College London, UK; Translational Imaging Group, Centre for Medical Image Computing, University College London, UK
| | - K J Friston
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, UK
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Foster-Dingley JC, van der Grond J, Moonen JEF, van den Berg-Huijsmans AA, de Ruijter W, van Buchem MA, de Craen AJM, van der Mast RC. Lower Blood Pressure Is Associated With Smaller Subcortical Brain Volumes in Older Persons. Am J Hypertens 2015; 28:1127-33. [PMID: 25714132 DOI: 10.1093/ajh/hpv006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 01/13/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Both high and low blood pressure (BP) have been positively as well as negatively associated with brain volumes in a variety of populations. The objective of this study was to investigate whether BP is associated with cortical and subcortical brain volumes in older old persons with mild cognitive deficits. METHODS Within the Discontinuation of Antihypertensive Treatment in the Elderly trial, the cross-sectional relation of BP parameters with both cortical and subcortical brain volumes was investigated in 220 older old persons with mild cognitive deficits (43% men, mean age = 80.7 (SD = 4.1), median Mini-Mental State Examination score = 26 (interquartile range: 25-27)), using linear regression analysis. All analyses were adjusted for age, gender, volume of white matter hyperintensities, and duration of antihypertensive treatment. Brain volumes were determined on 3DT1-weighted brain magnetic resonance imaging scans. RESULTS Lower systolic BP, diastolic BP, and mean arterial pressure (MAP) were significantly associated with lower volumes of thalamus and putamen (all P ≤ 0.01). In addition, lower MAP was also associated with reduced hippocampal volume (P = 0.035). There were no associations between any of the BP parameters with cortical gray matter or white matter volume. CONCLUSION In an older population using antihypertensive medication with mild cognitive deficits, a lower BP, rather than a high BP is associated with reduced volumes of thalamus, putamen, and hippocampus.
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Affiliation(s)
| | - Jeroen van der Grond
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Justine E F Moonen
- Department of Psychiatry, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Wouter de Ruijter
- Department of Public health and Primary care, Leiden University Medical Center, Leiden, the Netherlands
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Anton J M de Craen
- Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands
| | - Roos C van der Mast
- Department of Psychiatry, Leiden University Medical Center, Leiden, the Netherlands
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Srinivasa RN, Rossetti HC, Gupta MK, Rosenberg RN, Weiner MF, Peshock RM, McColl RW, Hynan LS, Lucarelli RT, King KS. Cardiovascular Risk Factors Associated with Smaller Brain Volumes in Regions Identified as Early Predictors of Cognitive Decline. Radiology 2015. [PMID: 26218598 DOI: 10.1148/radiol.2015142488] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE To determine in a large multiethnic cohort the cardiovascular and genetic risk factors associated with smaller volume in the hippocampus, precuneus, and posterior cingulate, and their association with preclinical deficits in cognitive performance in patients younger and older than 50 years. MATERIALS AND METHODS The institutional review board approved the study and all participants provided written informed consent. Eligible for this study were 1629 participants (700 men and 929 women; mean age, 50.0 years ± 10.2 [standard deviation]) drawn from the population-based Dallas Heart Study who underwent laboratory and clinical analysis in an initial baseline visit and approximately 7 years later underwent brain magnetic resonance imaging with automated volumetry and cognitive assessment with the Montreal Cognitive Assessment (MoCA). Regression analysis showed associations between risk factors and segmental volumes, and associations between these volumes with cognitive performance in participants younger and older than 50 years. RESULTS Lower hippocampal volume was associated with previous alcohol consumption (standardized estimate, -0.04; P = .039) and smoking (standardized estimate, -0.04; P = .048). Several risk factors correlated with lower total brain, posterior cingulate, and precuneus volumes. Higher total (standardized estimate, 0.06; P = .050), high-density lipoprotein (standardized estimate, 0.07; P = .003), and low-density lipoprotein (standardized estimate, 0.04; P = .037) cholesterol levels were associated with larger posterior cingulate volume, and higher triglyceride levels (standardized estimate, 0.06; P = .004) were associated with larger precuneus volume. Total MoCA score was associated with posterior cingulate volume (standardized estimate, 0.13; P = .001) in younger individuals and with hippocampal (standardized estimate, 0.06; P < .05) and precuneus (standardized estimate, 0.08; P < .023) volumes in older adults. CONCLUSION Smaller volumes in specific brain regions considered to be early markers of dementia risk were associated with specific cardiovascular disease risk factors and cognitive deficits in a predominantly midlife multiethnic population-based sample. Additionally, the risk factors most associated with these brain volumes differed in participants younger and older than 50 years, as did the association between brain volume and MoCA score.
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Affiliation(s)
- Rajiv N Srinivasa
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Heidi C Rossetti
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Mohit K Gupta
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Roger N Rosenberg
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Myron F Weiner
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Ronald M Peshock
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Roderick W McColl
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Linda S Hynan
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Richard T Lucarelli
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
| | - Kevin S King
- From the University of Texas Southwestern Medical Center, Department of Radiology, 5323 Harry Hines Blvd, Dallas, TX 75390
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de Bruijn RFAG, Ikram MA. Cardiovascular risk factors and future risk of Alzheimer's disease. BMC Med 2014; 12:130. [PMID: 25385322 PMCID: PMC4226863 DOI: 10.1186/s12916-014-0130-5] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/15/2014] [Indexed: 11/16/2022] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder in elderly people, but there are still no curative options. Senile plaques and neurofibrillary tangles are considered hallmarks of AD, but cerebrovascular pathology is also common. In this review, we summarize findings on cardiovascular disease (CVD) and risk factors in the etiology of AD. Firstly, we discuss the association of clinical CVD (such as stroke and heart disease) and AD. Secondly, we summarize the relation between imaging makers of pre-clinical vascular disease and AD. Lastly, we discuss the association of cardiovascular risk factors and AD. We discuss both established cardiovascular risk factors and emerging putative risk factors, which exert their effect partly via CVD.
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Affiliation(s)
| | - M Arfan Ikram
- Department of Epidemiology, Erasmus MC University Medical Center, Wytemaweg 80, Rotterdam, 3015, CN, the Netherlands.
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16
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Lockhart SN, DeCarli C. Structural imaging measures of brain aging. Neuropsychol Rev 2014; 24:271-89. [PMID: 25146995 PMCID: PMC4163469 DOI: 10.1007/s11065-014-9268-3] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 08/05/2014] [Indexed: 01/18/2023]
Abstract
During the course of normal aging, biological changes occur in the brain that are associated with changes in cognitive ability. This review presents data from neuroimaging studies of primarily "normal" or healthy brain aging. As such, we focus on research in unimpaired or nondemented older adults, but also include findings from lifespan studies that include younger and middle aged individuals as well as from populations with prodromal or clinically symptomatic disease such as cerebrovascular or Alzheimer's disease. This review predominantly addresses structural MRI biomarkers, such as volumetric or thickness measures from anatomical images, and measures of white matter injury and integrity respectively from FLAIR or DTI, and includes complementary data from PET and cognitive or clinical testing as appropriate. The findings reveal highly consistent age-related differences in brain structure, particularly frontal lobe and medial temporal regions that are also accompanied by age-related differences in frontal and medial temporal lobe mediated cognitive abilities. Newer findings also suggest that degeneration of specific white matter tracts such as those passing through the genu and splenium of the corpus callosum may also be related to age-related differences in cognitive performance. Interpretation of these findings, however, must be tempered by the fact that comorbid diseases such as cerebrovascular and Alzheimer's disease also increase in prevalence with advancing age. As such, this review discusses challenges related to interpretation of current theories of cognitive aging in light of the common occurrence of these later-life diseases. Understanding the differences between "Normal" and "Healthy" brain aging and identifying potential modifiable risk factors for brain aging is critical to inform potential treatments to stall or reverse the effects of brain aging and possibly extend cognitive health for our aging society.
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Affiliation(s)
- Samuel N. Lockhart
- Department of Neurology and Center for Neuroscience, University of California at Davis, Sacramento, CA, USA
| | - Charles DeCarli
- Department of Neurology and Center for Neuroscience, University of California at Davis, Sacramento, CA, USA
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Nazeri A, Ganjgahi H, Roostaei T, Nichols T, Zarei M. Imaging proteomics for diagnosis, monitoring and prediction of Alzheimer's disease. Neuroimage 2014; 102 Pt 2:657-65. [PMID: 25173418 DOI: 10.1016/j.neuroimage.2014.08.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 08/18/2014] [Accepted: 08/22/2014] [Indexed: 01/18/2023] Open
Abstract
Proteomic and imaging markers have been widely studied as potential biomarkers for diagnosis, monitoring and prognosis of Alzheimer's disease. In this study, we used Alzheimer Disease Neuroimaging Initiative dataset and performed parallel independent component analysis on cross sectional and longitudinal proteomic and imaging data in order to identify the best proteomic model for diagnosis, monitoring and prediction of Alzheimer disease (AD). We used plasma proteins measurement and imaging data from AD and healthy controls (HC) at the baseline and 1 year follow-up. Group comparisons at baseline and changes over 1 year were calculated for proteomic and imaging data. The results were fed into parallel independent component analysis in order to identify proteins that were associated with structural brain changes cross sectionally and longitudinally. Regression model was used to find the best model that can discriminate AD from HC, monitor AD and to predict MCI converters from non-converters. We showed that five proteins are associated with structural brain changes in the brain. These proteins could discriminate AD from HC with 57% specificity and 89% sensitivity. Four proteins whose change over 1 year were associated with brain structural changes could discriminate AD from HC with sensitivity of 93%, and specificity of 92%. This model predicted MCI conversion to AD in 2 years with 94% accuracy. This model has the highest accuracy in prediction of MCI conversion to AD within the ADNI-1 dataset. This study shows that combination of selected plasma protein levels and MR imaging is a useful method in identifying potential biomarker.
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Affiliation(s)
- Arash Nazeri
- Interdisciplinary Neuroscience Research Program, Tehran University of Medical Sciences, Tehran, 1417614411, Iran
| | - Habib Ganjgahi
- National Brain Mapping Centre, and Department of Neurology, Shahid Beheshti University of Medical Sciences, Tehran 4739, Iran; Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
| | - Tina Roostaei
- Interdisciplinary Neuroscience Research Program, Tehran University of Medical Sciences, Tehran, 1417614411, Iran
| | - Thomas Nichols
- Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
| | - Mojtaba Zarei
- National Brain Mapping Centre, and Department of Neurology, Shahid Beheshti University of Medical Sciences, Tehran 4739, Iran.
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Volume of the hippocampal subfields in healthy adults: differential associations with age and a pro-inflammatory genetic variant. Brain Struct Funct 2014; 220:2663-74. [PMID: 24947882 DOI: 10.1007/s00429-014-0817-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/05/2014] [Indexed: 12/14/2022]
Abstract
The hippocampus is one of the most age-sensitive brain regions, yet the mechanisms of hippocampal shrinkage remain unclear. Recent studies suggest that hippocampal subfields are differentially vulnerable to aging and differentially sensitive to vascular risk. Promoters of inflammation are frequently proposed as major contributors to brain aging and vascular disease but their effects on hippocampal subfields are unknown. We examined the associations of hippocampal subfield volumes with age, a vascular risk factor (hypertension), and genetic polymorphisms associated with variation in pro-inflammatory cytokines levels (IL-1β C-511T and IL-6 C-174G) and risk for Alzheimer's disease (APOEε4) in healthy adult volunteers (N = 80; age = 22-82 years). Volumes of three hippocampal subfields, cornu ammonis (CA) 1-2, CA3-dentate gyrus, and the subiculum were manually measured on high-resolution magnetic resonance images. Advanced age was differentially associated with smaller volume of CA1-2, whereas carriers of the T allele of IL-1β C-511T polymorphism had smaller volume of all hippocampal subfields than CC homozygotes did. Neither of the other genetic variants, nor diagnosis of hypertension, was associated with any of the measured volumes. The results support the notion that volumes of age-sensitive brain regions may be affected by pro-inflammatory factors that may be targeted by therapeutic interventions.
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Drachman DA. The amyloid hypothesis, time to move on: Amyloid is the downstream result, not cause, of Alzheimer's disease. Alzheimers Dement 2014; 10:372-80. [PMID: 24589433 DOI: 10.1016/j.jalz.2013.11.003] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/07/2013] [Accepted: 11/25/2013] [Indexed: 12/12/2022]
Abstract
The "amyloid hypothesis" has dominated Alzheimer research for more than 20 years, and proposes that amyloid is the toxic cause of neural/synaptic damage and dementia. If correct, decreasing the formation or removing amyloid should be therapeutic. Despite discrepancies in the proposed mechanism, and failed clinical trials, amyloid continues to be considered the cause of a degenerative cascade. Alternative hypotheses must explain three features: (i) why amyloid toxicity is not the etiology of Alzheimer's disease (AD), (ii) what alternative mechanisms cause the degeneration and dementia of AD, and (iii) why increased amyloid accumulates in the brain in AD. We propose that AD, which occurs in elderly, already vulnerable brains, with multiple age-related changes, is precipitated by impaired microvascular function, resulting primarily from decreased Notch-related angiogenesis. With impaired microvasculature, a lack of vascular endothelial-derived trophic factors and decreased cerebral blood flow cause the atrophy of neural structures. Therapeutic strategies should focus on supporting normal angiogenesis.
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