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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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Matura S, Prvulovic D, Hartmann D, Scheibe M, Sepanski B, Butz M, Oertel-Knöchel V, Knöchel C, Karakaya T, Fußer F, Hattingen E, Pantel J. Age-Related Effects of the Apolipoprotein E Gene on Brain Function. J Alzheimers Dis 2016; 52:317-31. [DOI: 10.3233/jad-150990] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Silke Matura
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
- Institute of General Practice, Goethe University, Frankfurt/Main, Germany
| | - David Prvulovic
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Daniel Hartmann
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Monika Scheibe
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Beate Sepanski
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Marius Butz
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Viola Oertel-Knöchel
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | | | - Tarik Karakaya
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Fabian Fußer
- Laboratory of Neurophysiology and Neuroimaging, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Goethe University, Frankfurt/Main, Germany
| | - Elke Hattingen
- Institute of Neuroradiology, Goethe University, Frankfurt/Main, Germany
| | - Johannes Pantel
- Institute of General Practice, Goethe University, Frankfurt/Main, Germany
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Ban CX, Zhong L, Wang T, Zhu MJ, Wang JH, Zhang ZL, Wang Z, Su N, Liu YY, Shi YC, Xiao SF, Li X. Enhanced Diabetes Susceptibility in Community Dwelling Han Elders Carrying the Apolipoprotein E 3/3 Genotype. PLoS One 2016; 11:e0151336. [PMID: 26998902 PMCID: PMC4801405 DOI: 10.1371/journal.pone.0151336] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 02/26/2016] [Indexed: 11/30/2022] Open
Abstract
Despite Apolipoprotein E (ApoE) being one of the main apolipoproteins in the blood, the association between its genotype and the high cholesterol or blood glucose levels commonly seen in clinical practice is inconclusive. Such research is also lacking in the Han population. The aim of this study was to investigate the association between APOE genotype, diabetes, and plasma glucose and lipid levels. We included 243 community-dwelling elderly residents in this study. Participant APOE genotypes were assessed and were simultaneously tested for weight, height, blood glucose, triglycerides, cholesterol, and high- and low-density lipoprotein. In addition, gender, age, years of education, cognitive function, and medical history was recorded. Subjects were divided into 3 groups based on APOE genotype: APOE ε2 group (ε2/ε2 and ε2/ε3), APOE ε3 group (ε3/ε3), and APOE ε4 group (ε2/ε4, ε3/ε4 and ε4/ε4). Comparisons between groups were conducted for the incidence of diabetes, high blood pressure, and dementia, as well as for differences in body-mass index, fasting plasma glucose, and blood lipids. The APOE ε3/ε3 genotype exhibited the highest frequency (70.4%) among the subjects. Participants in the APOE ε3 group demonstrated significantly higher levels of fasting plasma glucose than those in the APOE ε2 and APOE ε4 groups (P<0.05). The APOE ε3 group had slightly higher abnormal fasting plasma glucose values than did the APOE ε2 group (P = 0.065). Furthermore, the APOE3 genotype was significantly correlated with both fasting plasma glucose level and glucose abnormality (P< 0.05) and trended toward statistically significant correlation with diabetes (P = 0.082). The correlation between APOE2 and low low-density lipoprotein levels also approached statistical significance (P = 0.052). Thus, elderly community dwelling residents of Han ethnicity carrying the APOE ε3/ε3 genotype might have higher plasma glucose levels and a higher occurrence of diabetes.
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Affiliation(s)
- Chun-xia Ban
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Zhong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Tao Wang
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Min-jie Zhu
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing-hua Wang
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhen-lian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Zhe Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Ning Su
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuan-yuan Liu
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan-chen Shi
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shi-fu Xiao
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xia Li
- Department of Psychogeriatrics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Lee A, Qiu A. Modulative effects of COMT haplotype on age-related associations with brain morphology. Hum Brain Mapp 2016; 37:2068-82. [PMID: 26920810 DOI: 10.1002/hbm.23161] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 12/25/2022] Open
Abstract
Catechol-O-methyltransferase (COMT), located on chromosome 22q11.2, encodes an enzyme critical for dopamine flux in the prefrontal cortex. Genetic variants of COMT have been suggested to functionally manipulate prefrontal morphology and function in healthy adults. This study aims to investigate modulative roles of individuals COMT SNPs (rs737865, val158met, rs165599) and its haplotypes in age-related brain morphology using an Asian sample with 174 adults aged from 21 to 80 years. We showed an age-related decline in cortical thickness of the dorsal visual pathway, including the left dorsolateral prefrontal cortex, bilateral angular gyrus, right superior frontal cortex, and age-related shape compression in the basal ganglia as a function of the genotypes of the individual COMT SNPs, especially COMT val158met. Using haplotype trend regression analysis, COMT haplotype probabilities were estimated and further revealed an age-related decline in cortical thickness in the default mode network (DMN), including the posterior cingulate, precuneus, supramarginal and paracentral cortex, and the ventral visual system, including the occipital cortex and left inferior temporal cortex, as a function of the COMT haplotype. Our results provided new evidence on an antagonistic pleiotropic effect in COMT, suggesting that genetically programmed neural benefits in early life may have a potential bearing towards neural susceptibility in later life. Hum Brain Mapp 37:2068-2082, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Annie Lee
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Anqi Qiu
- Department of Biomedical Engineering, National University of Singapore, Singapore, 117576, Singapore.,Clinical Imaging Research Center, National University of Singapore, Singapore, 117456, Singapore.,Singapore Institute for Clinical Sciences, the Agency for Science, Technology and Research, Singapore, 117609, Singapore
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Padgett CR, Summers MJ, Vickers JC, McCormack GH, Skilbeck CE. Exploring the effect of the apolipoprotein E (APOE) gene on executive function, working memory, and processing speed during the early recovery period following traumatic brain injury. J Clin Exp Neuropsychol 2016; 38:551-60. [PMID: 26898659 DOI: 10.1080/13803395.2015.1137557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
INTRODUCTION There is evidence that the e4 allele of the apolipoprotein E (APOE) gene is detrimental to cognitive function, but results from traumatic brain injury (TBI) populations are mixed. A possible explanation is that APOEe2 carriers have routinely been incorporated into APOEe4 and non-e4 groups, despite APOEe2 being proposed to have an ameliorative effect. Our primary aim was to investigate the influence of APOEe4 on cognitive impairment during early recovery following TBI, excluding the potential confound of APOEe2 possession. A secondary objective was to explore whether APOEe4 displays more pronounced effects in moderate to severe TBI and to consider the potential postinjury protective influence of the APOEe2 allele. METHOD Participants who recently sustained a TBI (posttraumatic amnesia > 5 minutes) were assessed on measures of information processing speed, executive function, and working memory upon remission of posttraumatic amnesia. APOE genotype was determined by buccal saliva DNA extraction (APOEe4 n = 37, APOEe3 n = 92, APOEe2 n = 13). RESULTS Stepwise multiple regressions were performed to compare APOEe4 carriers to APOEe3 homozygotes, with injury severity, age, and estimated premorbid IQ included in the first step. This model was found to significantly predict performance on all tasks, accounting for 17.3-24.3% of the variance. When APOEe4 status was added for the second step, there were no significant changes on any tasks (additional variance <1%). The effect of APOEe4 in moderate to severe TBI and the effect of APOEe2 were explored by analysis of covariance (ANCOVA), with no significant effects revealed. CONCLUSIONS It is unlikely that APOE genotype influences cognitive function in the initial recovery period following TBI, regardless of injury severity. However, a more nuanced and long-term exploration of the effect of APOE genotype in the TBI population is warranted.
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Affiliation(s)
- Christine R Padgett
- a School of Medicine , University of Tasmania , Launceston , TAS , Australia.,b Tasmanian Neurotrauma Register , Royal Hobart Hospital , Hobart , TAS , Australia
| | - Mathew J Summers
- c School of Social Sciences , University of the Sunshine Coast , Maroochydore , QLD , Australia.,d Wicking Dementia Research and Education Centre , University of Tasmania , Hobart , TAS , Australia
| | - James C Vickers
- d Wicking Dementia Research and Education Centre , University of Tasmania , Hobart , TAS , Australia
| | - Graeme H McCormack
- d Wicking Dementia Research and Education Centre , University of Tasmania , Hobart , TAS , Australia
| | - Clive E Skilbeck
- a School of Medicine , University of Tasmania , Launceston , TAS , Australia.,b Tasmanian Neurotrauma Register , Royal Hobart Hospital , Hobart , TAS , Australia
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Polito L, Poloni TE, Vaccaro R, Abbondanza S, Mangieri M, Davin A, Villani S, Guaita A. High homocysteine and epistasis between MTHFR and APOE: association with cognitive performance in the elderly. Exp Gerontol 2016; 76:9-16. [PMID: 26774227 DOI: 10.1016/j.exger.2016.01.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 12/18/2015] [Accepted: 01/12/2016] [Indexed: 11/29/2022]
Abstract
High total homocysteine (tHcy) is associated with cognitive impairment in the elderly. The impact of high tHcy on different cognitive domains deserves further investigation, as does the role of the C677T polymorphism of the 5,10 methylenetetrahydrofolate reductase (MTHFR) gene. A cross-sectional analysis of 903 subjects from the population-based "InveCe.Ab" study was performed. The participants had no psychosis or active neurological disorders. They underwent a neuropsychological assessment. Principal component analysis allowed cognitive performance to be condensed into two components: executive functions and memory. Novel components were evaluated for association with tHcy, controlling for potential confounders. Regression models showed that high serum tHcy was associated with lower executive functions, but not with memory. MTHFR C677T TT was associated with higher tHcy but did not affect cognitive performance per se. However, when combined with the apolipoprotein E (APOE)-ε4 allele, it was a risk factor for lower executive performance, independently of tHcy levels. In summary, high tHcy per se, or MTHFR C677T TT in combination with the APOE-ε4 allele, might be associated primarily with executive dysfunctions rather than memory loss.
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Affiliation(s)
- Letizia Polito
- "Golgi Cenci" Foundation, Abbiategrasso 20081, Milan, Italy.
| | - Tino Emanuele Poloni
- "Golgi Cenci" Foundation, Abbiategrasso 20081, Milan, Italy; "C. Golgi" Geriatric Institute, Abbiategrasso 20081, Milan, Italy
| | - Roberta Vaccaro
- "Golgi Cenci" Foundation, Abbiategrasso 20081, Milan, Italy; "C. Golgi" Geriatric Institute, Abbiategrasso 20081, Milan, Italy
| | | | | | - Annalisa Davin
- "Golgi Cenci" Foundation, Abbiategrasso 20081, Milan, Italy
| | - Simona Villani
- Department of Public Health, Experimental and Forensic Medicine, Unit of Biostatistics and Clinical Epidemiology, University of Pavia, Pavia 27100, Italy
| | - Antonio Guaita
- "Golgi Cenci" Foundation, Abbiategrasso 20081, Milan, Italy
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Rusted J, Carare RO. Are the effects of APOE ϵ4 on cognitive function in nonclinical populations age- and gender-dependent? Neurodegener Dis Manag 2016; 5:37-48. [PMID: 25711453 DOI: 10.2217/nmt.14.43] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
APOE ϵ4 - one of three possible allelic variants (ϵ2, ϵ3 and ϵ4) of the polymorphic protein APOE - is well characterized in its role as the strongest risk factor (after old age) for sporadic Alzheimer's disease (AD). Perhaps less well known, and certainly less well characterized, is that this ϵ4 variant of the APOE gene also is a significant risk factor for age-related cognitive decline in nonclinical populations. This article considers APOE ϵ4 effects on cognition in people without dementia, the extent to which such effects may depend on age and on gender and other interactive biological systems that change across the lifespan.
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Stening E, Persson J, Eriksson E, Wahlund LO, Zetterberg H, Söderlund H. Apolipoprotein E ϵ4 is positively related to spatial performance but unrelated to hippocampal volume in healthy young adults. Behav Brain Res 2015; 299:11-8. [PMID: 26581118 DOI: 10.1016/j.bbr.2015.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/17/2015] [Accepted: 11/06/2015] [Indexed: 12/30/2022]
Abstract
The apolipoprotein E (APOE) ϵ4 allele is known to be a major genetic risk factor for Alzheimer's disease (AD). It has been linked to especially episodic memory decline and hippocampal atrophy in both healthy and demented elderly populations. In young adults, ϵ4 carriers have shown better performance in episodic memory compared to non-carriers. Spatial memory, however, has not been thoroughly assessed in relation to APOE in spite of its dependence on the hippocampus. In this study, we assessed the effect of APOE genotype on a variety of spatial and episodic memory tasks as well as hippocampal volume assessed through manual tracing in a sample of young adults (N=123). We also assessed whether potential effects were modulated by sex. The presence of one or more ϵ4 alleles had positive effects on spatial function and memory and object location memory, but no effect on word recognition. Men were superior to women in spatial function and memory but there were no sex differences in the other tasks. In spite of APOE ϵ4 carriers having superior performance in several memory tasks, no difference was found as a function of APOE genotype in hippocampal volume. To our knowledge, this study is the first to show that APOE ϵ4 has a positive effect on spatial ability in young adults.
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Affiliation(s)
- Eva Stening
- Department of Psychology, Uppsala University, Uppsala, Sweden.
| | - Jonas Persson
- Department of Psychology, Uppsala University, Uppsala, Sweden
| | - Elias Eriksson
- Department of Pharmacology, Institute of Physiology and Neuroscience, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Lars-Olof Wahlund
- Department of Neurobiology, Care Sciences and Society, Division of Clinical Geriatrics, Karolinska Institute, Stockholm, Sweden
| | - Henrik Zetterberg
- Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
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Greenwood PM, Espeseth T, Lin MK, Reinvang I, Parasuraman R. Longitudinal change in working memory as a function of APOE genotype in midlife and old age. Scand J Psychol 2015; 55:268-77. [PMID: 24853824 DOI: 10.1111/sjop.12123] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/17/2014] [Indexed: 01/17/2023]
Abstract
Previous investigations into whether the APOE-ε4 allele exerts cognitive effects at midlife have been inconclusive. We have advanced a "cognitive phenotype" hypothesis arguing that the ε4 allele of the apolipoprotein E gene (APOE) is associated with lower efficiency of neuronal plasticity thereby resulting in poorer cognitive performance independently of the pathology of Alzheimer's disease (Greenwood et al., ). This hypothesis is best tested at midlife, prior to the neuron loss associated with AD diagnosis. This hypothesis predicts that the ε4 allele would alter cognition regardless of age through plasticity mechanisms, but would not induce longitudinal decline in midlife. The alternative "prodrome" hypothesis predicts that the APOE-ε4 allele would be associated with longitudinal cognitive decline as early as midlife due to prodromal effects of AD. We tested these hypotheses with a working memory task in a large cross-sectional sample of cognitively screened APOE-ε4 carriers and non-carriers and also in a small longitudinal sample over 3 years. The sample was divided into middle-aged (mean age 50, range 40-59) and older (mean age 69, range 60-84) individuals. Cross-sectionally, we observed that older, but not middle-aged, APOE-ε4 carriers had lower accuracy than ε4 non-carriers, mainly under the hardest discrimination condition. Longitudinally, we observed increases in accuracy in middle-aged APOE-ε4 carriers, suggesting a cognitive phenotype that includes ability to benefit from experience. We observed a longitudinal decrease in older APOE-ε4 carriers, suggesting an AD prodrome.
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Albert M, Soldan A, Gottesman R, McKhann G, Sacktor N, Farrington L, Grega M, Turner R, Lu Y, Li S, Wang MC, Selnes O. Cognitive changes preceding clinical symptom onset of mild cognitive impairment and relationship to ApoE genotype. Curr Alzheimer Res 2015; 11:773-84. [PMID: 25212916 DOI: 10.2174/156720501108140910121920] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 07/13/2014] [Accepted: 07/28/2014] [Indexed: 01/13/2023]
Abstract
BACKGROUND This study had two goals (1) to evaluate changes in neuropsychological performance among cognitively normal individuals that might precede the onset of clinical symptoms, and (2) to examine the impact of Apolipoprotein E (ApoE) genotype on these changes. METHODS Longitudinal neuropsychological, clinical assessments and consensus diagnoses were completed prospectively in 268 cognitively normal individuals. The mean duration of follow-up was 9.2 years (+/- 3.3). 208 participants remained normal and 60 developed cognitive decline, consistent with a diagnosis of MCI or dementia. Cox regression analyses were completed, for both baseline scores and rate of change in scores, in relation to time to onset of clinical symptoms. Analyses were completed both with and without ApoE-4 status included. Interactions with ApoE-4 status were also examined. RESULTS Lower baseline test scores, as well as greater rate of change in test scores, were associated with time to onset of clinical symptoms (p<0.001). The mean time from baseline to onset of clinical symptoms was 6.15 (+/- 3.4) years. The presence of an ApoE-4 allele doubled the risk of progression. The rate of change in two of the test scores was significantly different in ApoE-4 carriers vs. non-carriers. CONCLUSIONS Cognitive performance declines prior to the onset of clinical symptoms that are a harbinger of a diagnosis of MCI. Cognitive changes in normal individuals who will subsequently decline may be observed at least 6.5 years prior to symptom onset. In addition, the risk of decline is doubled among individuals with an ApoE-4 allele.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Ola Selnes
- Johns Hopkins School of Medicine - Neurology 1620 McElderry Street Reed Hall West 1 , Baltimore, Maryland 21205 United States.
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Kuczmarski MF, Allegro D, Stave E. The association of healthful diets and cognitive function: a review. J Nutr Gerontol Geriatr 2015; 33:69-90. [PMID: 24827060 DOI: 10.1080/21551197.2014.907101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The association of diet with mild cognitive impairment has not been extensively studied. Consumption of a healthful diet may help to attenuate age-related decline in older adults. Published studies have suggested that greater adherence to a Mediterranean-style dietary pattern is associated with a lower risk of developing Alzheimer's disease and with a slower rate of cognitive decline with age. However, published findings are inconsistent. The discrepancies most likely can be explained by the variations in both dietary and cognitive methodologies. It is not clear how diet contributes to the development of neurocognitive changes with age. This review will update available knowledge on the relationship between adherence to healthful diets and cognition and document the need for researchers to adopt more coherent and uniform methodology to allow for better quantification of the association of diet with cognitive function. There appears to be a relationship between diet and cognition.
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Affiliation(s)
- Marie Fanelli Kuczmarski
- a Department of Behavioral Health and Nutrition , University of Delaware , Newark , Delaware , USA
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Zhang CC, Ren HY, Li ML, Wang Q, Deng W, Guo WJ, Lei W, Xiang B, Zhao LS, Ma XH, Yao YG, Li T. Apolipoprotein E gene polymorphisms associated with processing speed and executive functions in healthy Han Chinese. Neurosci Bull 2015; 31:368-70. [PMID: 25827315 DOI: 10.1007/s12264-014-1515-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/19/2015] [Indexed: 02/05/2023] Open
Affiliation(s)
- Cheng-Cheng Zhang
- The Mental Health Center, West China Hospital, Sichuan University, Chengdu, 610041, China
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McFall GP, Wiebe SA, Vergote D, Westaway D, Jhamandas J, Bäckman L, Dixon RA. ApoE and pulse pressure interactively influence level and change in the aging of episodic memory: Protective effects among ε2 carriers. Neuropsychology 2014; 29:388-401. [PMID: 25436424 DOI: 10.1037/neu0000150] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE We tested independent and interactive effects of Apolipoprotein E (ApoE) and pulse pressure (PP) concurrently and longitudinally across 9 years (3 waves) of episodic (EM) and semantic memory (SM) data from the Victoria Longitudinal Study. METHOD We assembled a sample of older adults (n = 570, baseline M age = 71, age range = 53-95) and used latent growth modeling to test 4 research goals. RESULTS First, the best fitting memory model was 2 single latent variables for EM and SM, each exhibiting configural, metric, and partial scalar invariance. This model was analyzed as a parallel process model. Second, baseline level of PP predicted EM performance at centering age (75) and rate of 9-year EM change. Third, we observed no main effects of ApoE on EM or SM. Fourth, EM was affected by higher PP but differentially less so for carriers of the ApoE ε2 allele than the ε3 or ε4 alleles. CONCLUSIONS PP is confirmed as a risk factor for concurrent and changing cognitive health in aging, but the effects operate differently across risk and protective allelic distribution of the ApoE gene.
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Shu H, Shi Y, Chen G, Wang Z, Liu D, Yue C, Ward BD, Li W, Xu Z, Chen G, Guo Q, Xu J, Li SJ, Zhang Z. Opposite Neural Trajectories of Apolipoprotein E ϵ4 and ϵ2 Alleles with Aging Associated with Different Risks of Alzheimer's Disease. Cereb Cortex 2014; 26:1421-1429. [PMID: 25336599 DOI: 10.1093/cercor/bhu237] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The apolipoprotein E (APOE) ϵ4 allele is a confirmed genetic risk factor and the APOE ϵ2 allele is a protective factor related to late-onset Alzheimer's disease (AD). Intriguingly, recent studies demonstrated similar brain function alterations between APOE ϵ2 and ϵ4 alleles, despite their opposite susceptibilities to AD. To address this apparent discrepancy, we recruited 129 cognitively normal elderly subjects, including 36 ϵ2 carriers, 44 ϵ3 homozygotes, and 49 ϵ4 carriers. All subjects underwent resting-state functional MRI scans. We hypothesized that aging could influence the APOE ϵ2 and ϵ4 allele effects that contribute to their appropriate AD risks differently. Using the stepwise regression analysis, we demonstrated that although both ϵ2 and ϵ4 carriers showed decreased functional connectivity (FC) compared with ϵ3 homozygotes, they have opposite aging trajectories in the default mode network-primarily in the bilateral anterior cingulate cortex. As age increased, ϵ2 carriers showed elevated FC, whereas ϵ4 carriers exhibited decreased FC. Behaviorally, the altered DMN FC positively correlated with information processing speed in both ϵ2 and ϵ4 carriers. It is suggested that the opposite aging trajectories between APOE ϵ2 and ϵ4 alleles in the DMN may reflect the antagonistic pleiotropic properties and associate with their different AD risks.
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Affiliation(s)
- Hao Shu
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China.,Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Yongmei Shi
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China
| | - Gang Chen
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Zan Wang
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China
| | - Duan Liu
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China
| | - Chunxian Yue
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China
| | - B Douglas Ward
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Wenjun Li
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Zhan Xu
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Guangyu Chen
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Qihao Guo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jun Xu
- Brain Center, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu, China
| | - Shi-Jiang Li
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Zhijun Zhang
- Department of Neurology, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, Jiangsu, China
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DiBattista AM, Stevens BW, Rebeck GW, Green AE. Two Alzheimer's disease risk genes increase entorhinal cortex volume in young adults. Front Hum Neurosci 2014; 8:779. [PMID: 25339884 PMCID: PMC4186290 DOI: 10.3389/fnhum.2014.00779] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/14/2014] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) risk genes alter brain structure and function decades before disease onset. Apolipoprotein E (APOE) is the strongest known genetic risk factor for AD, and a related gene, apolipoprotein J (APOJ), also affects disease risk. However, the extent to which these genes affect brain structure in young adults remains unclear. Here, we report that AD risk alleles of these two genes, APOE-ε4 and APOJ-C, cumulatively alter brain volume in young adults. Using voxel-based morphometry (VBM) in 57 individuals, we examined the entorhinal cortex, one of the earliest brain regions affected in AD pathogenesis. Apolipoprotein E-ε4 carriers exhibited higher right entorhinal cortex volume compared to non-carriers. Interestingly, APOJ-C risk genotype was associated with higher bilateral entorhinal cortex volume in non-APOE-ε4 carriers. To determine the combined disease risk of APOE and APOJ status per subject, we used cumulative odds ratios as regressors for volumetric measurements. Higher disease risk corresponded to greater right entorhinal cortex volume. These results suggest that, years before disease onset, two key AD genetic risk factors may exert influence on the structure of a brain region where AD pathogenesis takes root.
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Affiliation(s)
| | - Benson W Stevens
- Department of Neuroscience, Georgetown University Medical Center Washington, DC, USA ; Department of Psychology, Georgetown University Washington, DC, USA
| | - G William Rebeck
- Department of Neuroscience, Georgetown University Medical Center Washington, DC, USA
| | - Adam E Green
- Department of Psychology, Georgetown University Washington, DC, USA
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66
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Synergistic associations of catechol-O-methyltransferase and brain-derived neurotrophic factor with executive function in aging are selective and modified by apolipoprotein E. Neurobiol Aging 2014; 36:249-56. [PMID: 25107496 DOI: 10.1016/j.neurobiolaging.2014.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 06/16/2014] [Accepted: 06/16/2014] [Indexed: 11/23/2022]
Abstract
Genetic polymorphisms of catechol-O-methyltransferase (COMT) and brain-derived neurotrophic factor (BDNF) have shown promising but inconsistent linkages with executive function (EF) in normal aging. We tested (1) independent contributions of COMT and BDNF risk; (2) potential magnification by risk-related interactions or additive effects with age; and (3) effect modification through stratification by apolipoprotein E (APOE) (risk: ε4+). Multiple linear regression models were applied with nondemented older adults (N = 634; range: 53-95 years) for an EF latent variable. No independent effects of BDNF or COMT on EF were observed. Additive (but not interactive) effects of COMT, BDNF, and age showed that older adults with a high-risk allelic combination performed differentially worse. Of 2 tested models of synergistic effects, the additive approach selectively supported a magnification hypothesis, which was qualified by the presence or the absence of APOE ε4.
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Adluru N, Destiche DJ, Lu SYF, Doran ST, Birdsill AC, Melah KE, Okonkwo OC, Alexander AL, Dowling NM, Johnson SC, Sager MA, Bendlin BB. White matter microstructure in late middle-age: Effects of apolipoprotein E4 and parental family history of Alzheimer's disease. NEUROIMAGE-CLINICAL 2014; 4:730-42. [PMID: 24936424 PMCID: PMC4053649 DOI: 10.1016/j.nicl.2014.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 01/05/2023]
Abstract
INTRODUCTION Little is still known about the effects of risk factors for Alzheimer's disease (AD) on white matter microstructure in cognitively healthy adults. The purpose of this cross-sectional study was to assess the effect of two well-known risk factors for AD, parental family history and APOE4 genotype. METHODS This study included 343 participants from the Wisconsin Registry for Alzheimer's Prevention, who underwent diffusion tensor imaging (DTI). A region of interest analysis was performed on fractional anisotropy maps, in addition to mean, radial, and axial diffusivity maps, aligned to a common template space using a diffeomorphic, tensor-based registration method. The analysis focused on brain regions known to be affected in AD including the corpus callosum, superior longitudinal fasciculus, fornix, cingulum, and uncinate fasciculus. Analyses assessed the impact of APOE4, parental family history of AD, age, and sex on white matter microstructure in late middle-aged participants (aged 47-76 years). RESULTS Both APOE4 and parental family history were associated with microstructural white matter differences. Participants with parental family history of AD had higher FA in the genu of the corpus callosum and the superior longitudinal fasciculus. We observed an interaction between family history and APOE4, where participants who were family history positive but APOE4 negative had lower axial diffusivity in the uncinate fasciculus, and participants who were both family history positive and APOE4 positive had higher axial diffusivity in this region. We also observed an interaction between APOE4 and age, whereby older participants (=65 years of age) who were APOE4 carriers, had higher MD in the superior longitudinal fasciculus and in the portion of the cingulum bundle running adjacent to the cingulate cortex, compared to non-carriers. Older participants who were APOE4 carriers also showed higher radial diffusivity in the genu compared to non-carriers. Across all participants, age had an effect on FA, MD, and axial and radial diffusivities. Sex differences were observed in FA and radial diffusivity. CONCLUSION APOE4 genotype, parental family history of AD, age, and sex are all associated with microstructural white matter differences in late middle-aged adults. In participants at risk for AD, alterations in diffusion characteristics-both expected and unexpected-may represent cellular changes occurring at the earliest disease stages, but further work is needed. Higher mean, radial, and axial diffusivities were observed in participants who are more likely to be experiencing later stage preclinical pathology, including participants who were both older and carried APOE4, or who were positive for both APOE4 and parental family history of AD.
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Affiliation(s)
- Nagesh Adluru
- Waisman Laboratory for Brain Imaging and Behavior, Madison, WI, USA
| | | | | | - Samuel T Doran
- Waisman Laboratory for Brain Imaging and Behavior, Madison, WI, USA
| | - Alex C Birdsill
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA
| | - Kelsey E Melah
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA
| | - Ozioma C Okonkwo
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA
| | - Andrew L Alexander
- Waisman Laboratory for Brain Imaging and Behavior, Madison, WI, USA ; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, 1111 Highland Ave, Madison, WI 53705, USA ; University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, 6001 Research Park Blvd, Madison, WI 53719, USA
| | - N Maritza Dowling
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA ; Department of Biostatistics and Medical Informatics, 600 Highland Avenue, Madison, WI 53792, USA
| | - Sterling C Johnson
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA ; Geriatric Research, Education and Clinical Center (GRECC), William S. Middleton Memorial Veteran's Hospital, 2500 Overlook Terrace, Madison, WI 53705, USA ; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, 7818 Big Sky Drive, Madison, WI 53719, USA
| | - Mark A Sager
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA ; Geriatric Research, Education and Clinical Center (GRECC), William S. Middleton Memorial Veteran's Hospital, 2500 Overlook Terrace, Madison, WI 53705, USA ; Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, 7818 Big Sky Drive, Madison, WI 53719, USA
| | - Barbara B Bendlin
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Department of Medicine, 600 Highland Avenue, Madison, WI 53792, USA
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Verhaaren BFJ, Vernooij MW, Koudstaal PJ, Uitterlinden AG, van Duijn CM, Hofman A, Breteler MMB, Ikram MA. Alzheimer's disease genes and cognition in the nondemented general population. Biol Psychiatry 2013; 73:429-34. [PMID: 22592056 DOI: 10.1016/j.biopsych.2012.04.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2011] [Revised: 03/26/2012] [Accepted: 04/12/2012] [Indexed: 01/27/2023]
Abstract
BACKGROUND Genome-wide association studies have established 11 genes for late-onset Alzheimer's disease (AD). We investigated whether these genes jointly affect cognition in a nondemented population and improve prediction of AD. METHODS In 5171 nondemented people (age 45-99 years) from the population-based Rotterdam Study, we genotyped APOE-ε4 and single nucleotide polymorphisms from the genes CLU, PICALM, BIN1, CR1, ABCA7, MS4A6A, MS4A4E, CD2AP, EPHA1, and CD33. We constructed a genetic risk score by adding the risk alleles per individual weighted by the reported effect sizes. All people underwent cognitive testing. With linear regression we investigated the relationship between the genetic risk score and cognition, with and without APOE. In a subcohort, with more than 10 years of follow-up, we assessed whether the risk score predicted AD. RESULTS The genetic risk score was primarily associated with memory (standardized difference [95% confidence interval] per SD increase in genetic risk score: -.05[-.07; -.02], p = 1.5 * 10(-4)). This association attenuated when APOE was excluded from the genetic risk score (-.03[-.05; .00], p = .047) and would not survive a multiple-testing correction. Similarly, we found that although the genetic risk score without APOE was associated with the development of AD (p = .010), it only marginally improved prediction of AD beyond age, sex, APOE (area under the curve: .8159 vs. .8148). CONCLUSIONS In nondemented people, there is only a marginal joint effect of AD genes on memory independent from APOE. Moreover, although associated with AD, these genes jointly hardly improve prediction of AD.
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Affiliation(s)
- Benjamin F J Verhaaren
- Department of Epidemiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
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Abstract
Apolipoprotein E (Apo-E) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the ε4 allele are at increased risk of AD compared with those carrying the more common ε3 allele, whereas the ε2 allele decreases risk. Presence of the APOE ε4 allele is also associated with increased risk of cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. Apo-E-lipoproteins bind to several cell-surface receptors to deliver lipids, and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. Apo-E isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on Apo-E in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different Apo-E isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting Apo-E.
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70
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Moreau PH, Bott JB, Zerbinatti C, Renger JJ, Kelche C, Cassel JC, Mathis C. ApoE4 confers better spatial memory than apoE3 in young adult hAPP-Yac/apoE-TR mice. Behav Brain Res 2013; 243:1-5. [PMID: 23291160 DOI: 10.1016/j.bbr.2012.12.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/21/2012] [Accepted: 12/24/2012] [Indexed: 12/17/2022]
Abstract
The APOE-ɛ4 allele is associated with increased cognitive decline during normal aging and Alzheimer's disease. However, several studies intriguingly found a beneficial effect on cognition in young adult human APOE-ɛ4 carriers. Here, we show that 3-month old bigenic hAPP-Yac/apoE4-TR mice outperformed their hAPP-Yac/apoE3-TR counterparts on learning and memory performances in the highly hippocampus-dependent, hidden-platform version of the Morris water maze task. The two mouse lines did not differ in a non-spatial visible-platform version of the task. This hAPP-Yac/apoE-TR model may thus provide a useful tool to study the mechanisms involved in the antagonistic pleiotropic effects of APOE-ɛ4 on cognitive functions.
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Affiliation(s)
- Pierre-Henri Moreau
- Laboratoire d'Imagerie et de Neurosciences Cognitives, UMR 7237 CNRS, Université de Strasbourg, IFR 37, GDR CNRS 2905, 12 rue Goethe, F-67000 Strasbourg, France
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Westlye ET, Hodneland E, Haász J, Espeseth T, Lundervold A, Lundervold AJ. Episodic memory of APOE ε4 carriers is correlated with fractional anisotropy, but not cortical thickness, in the medial temporal lobe. Neuroimage 2012; 63:507-16. [PMID: 22796460 DOI: 10.1016/j.neuroimage.2012.06.072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/08/2012] [Accepted: 06/29/2012] [Indexed: 01/25/2023] Open
Abstract
The ε4 allele of apolipoprotein E (apoE, protein; APOE, gene) is the most important genetic risk factor for the development of Alzheimer's disease (AD). Cortical structures in the medial temporal lobe (MTL) are important for memory function and are affected early in AD. Both gray matter (GM) and white matter (WM) structures in the MTL have been reported to display AD related changes in healthy APOE ε4 carriers, but the effects are relatively small and somewhat deviating. Still, there is a lack of studies directly linking structural measures with performance on psychometric tests in ε4+ individuals. We hypothesized that intact WM integrity in the MTL facilitates episodic memory, and predicted a higher correlation between WM integrity and memory performance in APOE ε4 carriers due to a possible limiting effect of WM microstructure. In the present study of 92 healthy (MMSE>27) participants we acquired T1 3D and DTI images from a 1.5T MRI scanner, and tested the participants with California Verbal Learning Test II (CVLT-II). The study had two main aims: 1) to relate verbal memory performance to entorhinal WM (EWM) integrity in APOE ε4 carriers and non-carriers, and 2) to investigate APOE ε4 effects on EWM and EC thickness. We observed a strong, positive correlation between FA in the EWM and memory performance, which was driven solely by APOE ε4 carriers. These effects were significant while controlling for age, sex, EWM volume and EC thickness. Although EC thickness was significantly reduced in ε4 carriers, we did not find a relationship between EC thickness and memory performance. Thus, increased susceptibility of the WM structures underpinning the entorhinal-hippocampal network, offers a plausible explanation for the earlier onset of cognitive decline previously reported in APOE ε4 carriers.
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Affiliation(s)
- Erling Tjelta Westlye
- Neuroinformatics and Image Analysis Laboratory, Department of Biomedicine, University of Bergen, NO-5020 Bergen, Norway.
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