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Sharp FR, DeCarli CS, Jin LW, Zhan X. White matter injury, cholesterol dysmetabolism, and APP/Abeta dysmetabolism interact to produce Alzheimer's disease (AD) neuropathology: A hypothesis and review. Front Aging Neurosci 2023; 15:1096206. [PMID: 36845656 PMCID: PMC9950279 DOI: 10.3389/fnagi.2023.1096206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/30/2023] [Indexed: 02/12/2023] Open
Abstract
We postulate that myelin injury contributes to cholesterol release from myelin and cholesterol dysmetabolism which contributes to Abeta dysmetabolism, and combined with genetic and AD risk factors, leads to increased Abeta and amyloid plaques. Increased Abeta damages myelin to form a vicious injury cycle. Thus, white matter injury, cholesterol dysmetabolism and Abeta dysmetabolism interact to produce or worsen AD neuropathology. The amyloid cascade is the leading hypothesis for the cause of Alzheimer's disease (AD). The failure of clinical trials based on this hypothesis has raised other possibilities. Even with a possible new success (Lecanemab), it is not clear whether this is a cause or a result of the disease. With the discovery in 1993 that the apolipoprotein E type 4 allele (APOE4) was the major risk factor for sporadic, late-onset AD (LOAD), there has been increasing interest in cholesterol in AD since APOE is a major cholesterol transporter. Recent studies show that cholesterol metabolism is intricately involved with Abeta (Aβ)/amyloid transport and metabolism, with cholesterol down-regulating the Aβ LRP1 transporter and upregulating the Aβ RAGE receptor, both of which would increase brain Aβ. Moreover, manipulating cholesterol transport and metabolism in rodent AD models can ameliorate pathology and cognitive deficits, or worsen them depending upon the manipulation. Though white matter (WM) injury has been noted in AD brain since Alzheimer's initial observations, recent studies have shown abnormal white matter in every AD brain. Moreover, there is age-related WM injury in normal individuals that occurs earlier and is worse with the APOE4 genotype. Moreover, WM injury precedes formation of plaques and tangles in human Familial Alzheimer's disease (FAD) and precedes plaque formation in rodent AD models. Restoring WM in rodent AD models improves cognition without affecting AD pathology. Thus, we postulate that the amyloid cascade, cholesterol dysmetabolism and white matter injury interact to produce and/or worsen AD pathology. We further postulate that the primary initiating event could be related to any of the three, with age a major factor for WM injury, diet and APOE4 and other genes a factor for cholesterol dysmetabolism, and FAD and other genes for Abeta dysmetabolism.
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Affiliation(s)
| | - Charles S. DeCarli
- Department of Neurology, The MIND Institute, University of California at Davis Medical Center, Sacramento, CA, United States
| | - Lee-Way Jin
- Department of Neurology, The MIND Institute, University of California at Davis Medical Center, Sacramento, CA, United States
| | - Xinhua Zhan
- Department of Neurology, The MIND Institute, University of California at Davis Medical Center, Sacramento, CA, United States
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Lavie I, Beeri MS, Berman Y, Schwartz Y, Soleimani L, Heymann A, Ravona-Springer R. Trajectories of depression symptoms over time differ by APOE4 genotype in older adults with type 2 diabetes. Int J Geriatr Psychiatry 2021; 36:1567-1575. [PMID: 34010987 PMCID: PMC8845090 DOI: 10.1002/gps.5583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/17/2021] [Indexed: 11/09/2022]
Abstract
OBJECTIVES The APOE-ε4 genotype has been associated with old-age depression, but this relationship has been rarely investigated in type 2 diabetes (T2D) older adults, who are at significantly increased risk for depression, a major contributor to T2D complications. We examined whether trajectories of depression symptoms over time differ by APOE-ε4 genotype in older adults with T2D. METHODS Participants (n = 754 [13.1% APOE-ε4 carrier]s) were from the longitudinal Israel Diabetes and Cognitive Decline (IDCD) study. They were initially cognitively normal and underwent evaluations of depression approximately every 18 months using the 15-item version of the Geriatric Depression Scale (GDS) and the depression subscale of the Neuropsychiatric Inventory (NPI). APOE was defined as a dichotomy of ε4 carriers and non-carriers. We used Hierarchical Linear Mixed Models (HLMM) that modeled the effects of APOE status on repeated GDS and NPI-depression scores in an unadjusted model (Model 1), adjusting for demographic factors (Model 2) and additionally adjusting for cardiovascular factors and global cognition (Model 3). RESULTS Participants' mean age was 71.37 (SD = 4.5); 38.2% female. In comparison to non-carriers, APOE-ε4 carriers had lower mean GDS scores (β = -0.46, p = 0.018) and lower NPI-depression scores (β = -0.170, p = 0.038) throughout all study follow period. The groups did not differ in the slope of change over time in GDS (β = -0.005, p = 0.252) or NPI-depression (β = -0.001, p = 0.994) scores. Additional adjustment for cardiovascular factors and global cognition did not alter these results. CONCLUSIONS In older adults with T2D, APOE-ε4 carriers have less depressive symptoms in successive measurements suggesting they may be less susceptible to depression.
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Affiliation(s)
- Inbar Lavie
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Michal Schnaider Beeri
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel,The Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA,Baruch Ivcher School of Psychology, Interdisciplinary Center, Herzliya, Israel
| | - Yuval Berman
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
| | - Yonathan Schwartz
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
| | - Laili Soleimani
- The Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Anthony Heymann
- Department of Family Medicine, Tel Aviv University, Tel Aviv, Israel,Maccabi Health Services, Tel Aviv, Israel
| | - Ramit Ravona-Springer
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel,The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel,Psychiatric Division, Sheba Medical Center, Tel-Hashomer, Israel
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Beach TG, Malek-Ahmadi M. Alzheimer's Disease Neuropathological Comorbidities are Common in the Younger-Old. J Alzheimers Dis 2021; 79:389-400. [PMID: 33285640 PMCID: PMC8034496 DOI: 10.3233/jad-201213] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Clinicopathological studies have demonstrated that Alzheimer's disease dementia (ADD) is often accompanied by clinically undetectable comorbid neurodegenerative and cerebrovascular disease that alter the rate of cognitive decline. Aside from causing increased variability in clinical response, it is possible that the major ADD comorbidities may not respond to ADD-specific molecular therapeutics. OBJECTIVE As most reports have focused on comorbidity in the oldest-old, its extent in younger age groups that are more likely to be involved in clinical trials is largely unknown; our objective is to provide this information. METHODS We conducted a survey of neuropathological comorbidities in sporadic ADD using data from the US National Alzheimer's Coordinating Center. Subject data was restricted to those with dementia and meeting National Institute on Aging-Alzheimer's Association intermediate or high AD Neuropathological Change levels, excluding those with known autosomal dominant AD-related mutations. RESULTS Highly prevalent ADD comorbidities are not restricted to the oldest-old but are common even in early-onset ADD. The percentage of cases with ADD as the sole major neuropathological diagnosis is highest in the under-60 group, where "pure" ADD cases are still in the minority at 44%. After this AD as a sole major pathology in ADD declines to roughly 20%in the 70s and beyond. Lewy body disease is the most common comorbidity at younger ages but actually is less common at later ages, while for most others, their prevalence increases with age. CONCLUSION Alzheimer's disease neuropathological comorbidities are highly prevalent even in the younger-old.
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Park J, Lai MKP, Arumugam TV, Jo DG. O-GlcNAcylation as a Therapeutic Target for Alzheimer's Disease. Neuromolecular Med 2020; 22:171-193. [PMID: 31894464 DOI: 10.1007/s12017-019-08584-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 12/13/2019] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and the number of elderly patients suffering from AD has been steadily increasing. Despite worldwide efforts to cope with this disease, little progress has been achieved with regard to identification of effective therapeutics. Thus, active research focusing on identification of new therapeutic targets of AD is ongoing. Among the new targets, post-translational modifications which modify the properties of mature proteins have gained attention. O-GlcNAcylation, a type of PTM that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to a protein, is being sought as a new target to treat AD pathologies. O-GlcNAcylation has been known to modify the two important components of AD pathological hallmarks, amyloid precursor protein, and tau protein. In addition, elevating O-GlcNAcylation levels in AD animal models has been shown to be effective in alleviating AD-associated pathology. Although studies investigating the precise mechanism of reversal of AD pathologies by targeting O-GlcNAcylation are not yet complete, it is clearly important to examine O-GlcNAcylation regulation as a target of AD therapeutics. This review highlights the mechanisms of O-GlcNAcylation and its role as a potential therapeutic target under physiological and pathological AD conditions.
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Affiliation(s)
- Jinsu Park
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Korea
- Department of Health Science and Technology, Sungkyunkwan University, Seoul, 06351, Korea
| | - Mitchell K P Lai
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore
| | - Thiruma V Arumugam
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Korea.
- Department of Physiology, Yong Loo Lin School Medicine, National University of Singapore, Singapore, 117593, Singapore.
- Department of Physiology, Anatomy & Microbiology, School of Life Sciences, La Trobe University, Bundoora, VIC, Australia.
| | - Dong-Gyu Jo
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Korea.
- Department of Health Science and Technology, Sungkyunkwan University, Seoul, 06351, Korea.
- Biomedical Institute for Convergence, Sungkyunkwan University, Suwon, 16419, Korea.
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Farhadi A, Vosough M, Zhang JS, Tahamtani Y, Shahpasand K. A Possible Neurodegeneration Mechanism Triggered by Diabetes. Trends Endocrinol Metab 2019; 30:692-700. [PMID: 31399291 DOI: 10.1016/j.tem.2019.07.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/08/2019] [Accepted: 07/12/2019] [Indexed: 01/14/2023]
Abstract
Several conditions result in neurodegeneration; among which diabetes mellitus (DM) is of crucial importance. Tau (τ) malfunction is a major pathological process participating in neurodegeneration. Despite extensive considerations, the actual causative link between DM and τ abnormalities remains uncertain thus far. Phosphorylated (p)-τ at Thr-Pro motifs can exist in the two distinct cis and trans conformations. cis is neurotoxic, and is accumulated upon various stress conditions, such as nutrition depletion. We assume that pathogenic cis p-τ is the central mediator of neurodegeneration in DM, and propose why different brain areas give various responses to stress conditions. We herein juxtapose recent approaches in diabetic neurodegeneration and propose a therapeutic target to stop neuronal loss during DM.
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Affiliation(s)
- Aisan Farhadi
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, IR 19395-4644, Iran; Department of Developmental Biology, University of Science and Culture, Tehran, Iran
| | - Massoud Vosough
- Department of Regenerative Biomedicine, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Jin-San Zhang
- International Collaborative Center on Growth Factor Research, and School of Pharmaceutical Sciences, Wenzhou Medical University; Institute of Life Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China; Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Yaser Tahamtani
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, IR 19395-4644, Iran.
| | - Koorosh Shahpasand
- Department of Brain and Cognitive Sciences, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, IR 19395-4644, Iran.
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Interaction of APOE e4 and poor glycemic control predicts white matter hyperintensity growth from 73 to 76. Neurobiol Aging 2017; 54:54-58. [PMID: 28324763 PMCID: PMC5407886 DOI: 10.1016/j.neurobiolaging.2017.02.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 02/13/2017] [Accepted: 02/19/2017] [Indexed: 11/22/2022]
Abstract
We examined whether apolipoprotein E (APOE) status interacts with vascular risk factors (VRFs) to predict the progression of white matter hyperintensities (WMHs) on brain MRI scans over a specific period of life in older age when the risk of dementia increases. At age 73 years, baseline VRFs were assessed via self-reported history of diabetes, hypertension, smoking, and hypercholesterolemia, and via objective measures of blood HbA1c, body mass index, diastolic and systolic blood pressure, and blood high-density lipoprotein to total cholesterol (HDL) ratio. APOE e4 allele was coded as either present or absent. WMH progression was measured on MRI over 3 years in 434 older adults, in a same-year-of-birth cohort. APOE e4 carriers with either a self-reported diagnosis of diabetes (β = 0.160, p = 0.002) or higher glycated hemoglobin levels (β = 0.114, p = 0.014) exhibited greater WMH progression, and the former survived correction for multiple testing. All other APOE-VRF interactions were nonsignificant (βinteraction < 0.056, p > 0.228). The results suggest that carrying the APOE “risk” e4 allele increases the risk of greater age-related WMH progression over the early part of the eighth decade of life, when combined with poorer glycemic control. The interaction effect was robust to co-occurring VRFs, suggesting a possible target for mitigating brain and cognitive aging at this age.
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Bender AR, Prindle JJ, Brandmaier AM, Raz N. White matter and memory in healthy adults: Coupled changes over two years. Neuroimage 2016; 131:193-204. [PMID: 26545457 PMCID: PMC4848116 DOI: 10.1016/j.neuroimage.2015.10.085] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 10/06/2015] [Accepted: 10/29/2015] [Indexed: 11/16/2022] Open
Abstract
Numerous cross-sectional studies have used diffusion tensor imaging (DTI) to link age-related differences in white matter (WM) anisotropy and concomitant decrements in cognitive ability. Due to a dearth of longitudinal evidence, the relationship between changes in diffusion properties of WM and cognitive performance remains unclear. Here we examine the relationship between two-year changes in WM organization and cognitive performance in healthy adults (N=96, age range at baseline=18-79 years). We used latent change score models (LCSM) to evaluate changes in age-sensitive cognitive abilities - fluid intelligence and associative memory. WM changes were assessed by fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) in WM regions that are considered part of established memory networks and exhibited individual differences in change. In modeling change, we postulated reciprocal paths between baseline measures and change factors, within and between WM and cognition domains, and accounted for individual differences in baseline age. Although baseline cross-sectional memory performance was positively associated with FA and negatively with RD, longitudinal effects told an altogether different story. Independent of age, longitudinal improvements in associative memory were significantly associated with linear reductions in FA and increases in RD. The present findings demonstrate the sensitivity of DTI-derived indices to changes in the brain and cognition and affirm the importance of longitudinal models for evaluating brain-cognition relations.
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Affiliation(s)
- Andrew R Bender
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
| | - John J Prindle
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Andreas M Brandmaier
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin, Germany
| | - Naftali Raz
- Institute of Gerontology & Department of Psychology, Wayne State University, Detroit, MI, USA
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Leritz EC, McGlinchey RE, Salat DH, Milberg WP. Elevated levels of serum cholesterol are associated with better performance on tasks of episodic memory. Metab Brain Dis 2016; 31:465-73. [PMID: 26873100 PMCID: PMC4913474 DOI: 10.1007/s11011-016-9797-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 01/18/2016] [Indexed: 01/14/2023]
Abstract
We examined how serum cholesterol, an established risk factor for cerebrovascular disease (CVD), relates to cognitive function in healthy middle-older aged individuals with no neurologic or CVD history. A complete lipid panel was obtained from a cohort of one hundred twenty individuals, ages 43-85, who also underwent a comprehensive neuropsychological examination. In order to reduce the number of variables and empirically identify broad cognitive domains, scores from neuropsychological tests were submitted into a factor analysis. This analysis revealed three explainable factors: Memory, Executive Function and Memory/Language. Three separate hierarchical multiple regression analyses were conducted using individual cholesterol metrics (total cholesterol, low density lipoprotein; LDL, high density lipoprotein; HDL, and triglycerides), as well as age, education, medication status (lipid lowering agents), ApoE status, and additional risk factors for CVD to predict neuropsychological function. The Memory Factor was predicted by a combination of age, LDL, and triglyceride levels; both age and triglycerides were negatively associated with factor score, while LDL levels revealed a positive relationship. Both the Executive and Memory/Language factor were only explained by education, whereby more years were associated with better performance. These results provide evidence that individual cholesterol lipoproteins and triglycerides may differentially impact cognitive function, over and above other common CVD risk factors and ApoE status. Our findings demonstrate the importance of consideration of vascular risk factors, such as cholesterol, in studies of cognitive aging.
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Affiliation(s)
- Elizabeth C Leritz
- Geriatric Research, Education and Clinical Center (GRECC), VA Boston Healthcare System, Boston, MA, USA.
- Neuroimaging Research for Veterans Center (NERVE), VA Boston Healthcare System, Boston, MA, USA.
- Harvard Medical School, Boston, MA, USA.
| | - Regina E McGlinchey
- Geriatric Research, Education and Clinical Center (GRECC), VA Boston Healthcare System, Boston, MA, USA
- Neuroimaging Research for Veterans Center (NERVE), VA Boston Healthcare System, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - David H Salat
- Geriatric Research, Education and Clinical Center (GRECC), VA Boston Healthcare System, Boston, MA, USA
- Neuroimaging Research for Veterans Center (NERVE), VA Boston Healthcare System, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, USA
| | - William P Milberg
- Geriatric Research, Education and Clinical Center (GRECC), VA Boston Healthcare System, Boston, MA, USA
- Neuroimaging Research for Veterans Center (NERVE), VA Boston Healthcare System, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
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Foley JM, Salat DH, Stricker NH, McGlinchey RE, Milberg WP, Grande LJ, Leritz EC. Glucose Dysregulation Interacts With APOE-∊4 to Potentiate Temporoparietal Cortical Thinning. Am J Alzheimers Dis Other Demen 2016; 31:76-86. [PMID: 26006791 PMCID: PMC4913470 DOI: 10.1177/1533317515587084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We examined the interactive effects of apolipoprotein ∊4 (APOE-∊4), a risk factor for Alzheimer's disease (AD), and diabetes risk on cortical thickness among 107 healthy elderly participants; in particular, participants included 27 APOE-∊4+ and 80 APOE-∊4- controls using T1-weighted structural magnetic resonance imaging. Regions of interests included select frontal, temporal, and parietal cortical regions. Among APOE-∊4, glucose abnormalities independently predicted reduced cortical thickness among temporoparietal regions but failed to predict changes for noncarriers. However, among noncarriers, age independently predicted reduced cortical thickness among temporoparietal and frontal regions. Diabetes risk is particularly important for the integrity of cortical gray matter in APOE-∊4 and demonstrates a pattern of thinning that is expected in preclinical AD. However, in the absence of this genetic factor, age confers risk for reduced cortical thickness among regions of expected compromise. This study supports aggressive management of cerebrovascular factors and earlier preclinical detection of AD among individuals presenting with genetic and metabolic risks.
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Affiliation(s)
- Jessica M Foley
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - David H Salat
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
| | - Nikki H Stricker
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Regina E McGlinchey
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - William P Milberg
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
| | - Laura J Grande
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Elizabeth C Leritz
- Department of Psychiatry, VA Boston Healthcare System, Boston, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA
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Bender AR, Raz N. Normal-appearing cerebral white matter in healthy adults: mean change over 2 years and individual differences in change. Neurobiol Aging 2015; 36:1834-48. [PMID: 25771392 DOI: 10.1016/j.neurobiolaging.2015.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 12/20/2022]
Abstract
Diffusion tensor imaging studies show age-related differences in cerebral white matter (WM). However, few have studied WM changes over time, and none evaluated individual differences in change across a wide age range. Here, we examined 2-year WM change in 96 healthy adults (baseline age, 19-78 years), individual differences in change, and the influence of vascular and metabolic risk thereon. Fractional anisotropy (FA), axial diffusivity, and radial diffusivity (RD) represented microstructural properties of normal-appearing WM within 13 regions. Cross-sectional analyses revealed age-related differences in all WM indices across the regions. In contrast, latent change score analyses showed longitudinal declines in axial diffusivity in association and projection fibers and increases in anterior commissural fibers. FA and RD evidenced a less consistent pattern of change. Metabolic risk mediated the effects of age on FA and RD change in corpus callosum body and dorsal cingulum. These findings underscore the importance of longitudinal studies in evaluating individual differences in change and the role of metabolic factors in shaping trajectories of brain aging.
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Affiliation(s)
- Andrew R Bender
- Institute of Gerontology, Wayne State University, Detroit, MI, USA.
| | - Naftali Raz
- Institute of Gerontology, Wayne State University, Detroit, MI, USA; Department of Psychology, Wayne State University, Detroit, MI, USA
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Suri S, Mackay CE, Kelly ME, Germuska M, Tunbridge EM, Frisoni GB, Matthews PM, Ebmeier KP, Bulte DP, Filippini N. Reduced cerebrovascular reactivity in young adults carrying the APOE ε4 allele. Alzheimers Dement 2014; 11:648-57.e1. [PMID: 25160043 DOI: 10.1016/j.jalz.2014.05.1755] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 05/06/2014] [Accepted: 05/29/2014] [Indexed: 01/10/2023]
Abstract
BACKGROUND Functional magnetic resonance imaging (MRI) studies have shown that APOE ε2- and ε4-carriers have similar patterns of blood-oxygenation-level-dependent (BOLD) activation suggesting that we need to look beyond the BOLD signal to link APOE's effect on the brain to Alzheimer's disease (AD)-risk. METHODS We evaluated APOE-related differences in BOLD activation in response to a memory task, cerebrovascular reactivity using a CO2-inhalation challenge (CO2-CVR), and the potential contribution of CO2-CVR to the BOLD signal. RESULTS APOE ε4-carriers had the highest task-related hippocampal BOLD signal relative to non-carriers. The largest differences in CO2-CVR were between ε2- and ε4-carriers, with the latter having the lowest values. Genotype differences in CO2-CVR accounted for ∼70% of hippocampal BOLD differences between groups. CONCLUSION Because CO2-CVR gauges vascular health, the differential effect of APOE in young adults may reflect a vascular contribution to the vulnerability of ε4-carriers to late-life pathology. Studies confirming our findings are warranted.
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Affiliation(s)
- Sana Suri
- Department of Psychiatry, University of Oxford, Oxford United Kingdom; Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom
| | - Clare E Mackay
- Department of Psychiatry, University of Oxford, Oxford United Kingdom; Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom
| | - Michael E Kelly
- Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom
| | - Michael Germuska
- Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom
| | | | - Giovanni B Frisoni
- Laboratory of Epidemiology, Neuroimaging, and Telemedicine, Istituto di Ricovero e Cura a Carattere Scientifico San Giovanni di Dio-Fatebenefratelli, Brescia, Italy; Department of Psychiatry, University Hospital and University of Geneva, Chene-Bourg, Switzerland
| | - Paul M Matthews
- Division of Brain Sciences, Imperial College, Hammersmith Campus London, United Kingdom
| | - Klaus P Ebmeier
- Department of Psychiatry, University of Oxford, Oxford United Kingdom
| | - Daniel P Bulte
- Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom
| | - Nicola Filippini
- Department of Psychiatry, University of Oxford, Oxford United Kingdom; Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford United Kingdom.
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