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Balietti M, Conti F. Environmental enrichment and the aging brain: is it time for standardization? Neurosci Biobehav Rev 2022; 139:104728. [PMID: 35691473 DOI: 10.1016/j.neubiorev.2022.104728] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/01/2022] [Accepted: 06/06/2022] [Indexed: 11/30/2022]
Abstract
Aging entails a progressive decline of cognitive abilities. However, since the brain is endowed with considerable plasticity, adequate stimulation can delay or partially compensate for age-related structural and functional impairment. Environmental enrichment (EE) has been reported to determine a wide range of cerebral changes. Although most findings have been obtained in young and adult animals, research has recently turned to aged individuals. Notably, EE can contribute identifying key lifestyle factors whose change can help extend the "mind-span", i.e., the time an individual lives in a healthy cognitive condition. Here we discuss specific methodological issues that can affect the outcomes of EE interventions applied to aged rodents, summarize the main variables that would need standardization (e.g., timing and duration, enrichment items, control animals and setting), and offer some suggestions on how this goal may be achieved. Reaching a consensus on EE experiment design would significantly reduce differences between and within laboratories, enable constructive discussions among researchers, and improve data interpretation.
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Affiliation(s)
- Marta Balietti
- Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy.
| | - Fiorenzo Conti
- Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy; Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy.
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2
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Bontempi P, Podda R, Daducci A, Sonato N, Fattoretti P, Fiorini S, Tambalo S, Mosconi E, Merigo F, Balietti M, Marzola P. MRI characterization of rat brain aging at structural and functional level: Clues for translational applications. Exp Gerontol 2021; 152:111432. [DOI: 10.1016/j.exger.2021.111432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/10/2021] [Accepted: 05/27/2021] [Indexed: 12/18/2022]
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3
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Dang C, Harrington KD, Lim YY, Ames D, Hassenstab J, Laws SM, Yassi N, Hickey M, Rainey-Smith SR, Robertson J, Rowe CC, Sohrabi HR, Salvado O, Weinborn M, Villemagne VL, Masters CL, Maruff P. Superior Memory Reduces 8-year Risk of Mild Cognitive Impairment and Dementia But Not Amyloid β-Associated Cognitive Decline in Older Adults. Arch Clin Neuropsychol 2020; 34:585-598. [PMID: 30272115 DOI: 10.1093/arclin/acy078] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/20/2018] [Accepted: 09/11/2018] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE To prospectively examine 8-year risk of clinical disease progression to mild cognitive impairment (MCI)/dementia in older adults ≥60 with superior episodic memory (SuperAgers) compared to those cognitively normal for their age (CNFA). Additionally, to determine the extent to which SuperAgers were resilient to the negative effects of elevated amyloid-beta (Aβ+) on cognition. METHOD Participants were classified as SuperAgers based on episodic memory performance consistent with younger adults aged 30-44 and no impairment on non-memory tests (n = 179), and were matched with CNFA on age, sex, education, and follow-up time (n = 179). Subdistribution hazard models examined risk of clinical progression to MCI/dementia. Linear mixed models assessed the effect of Aβ on cognition over time. RESULTS Prevalence of Aβ+ and APOE ε4 was equivalent between SuperAgers and CNFA. SuperAgers had 69%-73% reduced risk of clinical progression to MCI/dementia compared to CNFA (HR: 0.27-0.31, 95% CI: 0.11-0.73, p < .001). Aβ+ was associated with cognitive decline in verbal memory and executive function, regardless of SuperAger/CNFA classification. In the absence of Aβ+, equivalent age-related changes in cognition were observed between SuperAgers and CNFA. CONCLUSIONS SuperAgers displayed resilience against clinical progression to MCI/dementia compared to CNFA despite equivalent risk for Alzheimer's disease (AD); however, SuperAgers had no greater protection from Aβ+ than CNFA. The deleterious effects of Aβ on cognition persist regardless of baseline cognitive ability. Thus, superior cognitive performance does not reflect resistance against the neuropathological processes associated with AD, and the observed resilience for SuperAgers may instead reflect neuropsychological criteria for cognitive impairment.
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Affiliation(s)
- Christa Dang
- Department of Obstetrics and Gynaecology, Melbourne Medical School, The University of Melbourne, Parkville, Victoria, Australia.,The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Karra D Harrington
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia.,Cooperative Research Centre for Mental Health, Parkville, Victoria, Australia
| | - Yen Ying Lim
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - David Ames
- Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia.,National Ageing Research Institute, Parkville, Victoria, Australia
| | - Jason Hassenstab
- Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.,Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Department of Psychological & Brain Sciences, Washington University, St. Louis, MO, USA
| | - Simon M Laws
- Cooperative Research Centre for Mental Health, Parkville, Victoria, Australia.,Collaborative Genomics Group, Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.,School of Biomedical Sciences, Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Western Australia, Australia
| | - Nawaf Yassi
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia.,Department of Medicine and Neurology, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Martha Hickey
- Department of Obstetrics and Gynaecology, Melbourne Medical School, The University of Melbourne, Parkville, Victoria, Australia
| | - Stephanie R Rainey-Smith
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.,Australian Alzheimer's Research Foundation, Ralph and Patricia Sarich Neuroscience Research Institute, Nedlands, Western Australia, Australia
| | - Joanne Robertson
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Christopher C Rowe
- Department of Molecular Imaging & Therapy, Austin Health, Melbourne, Victoria, Australia.,Department of Medicine, Austin Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Hamid R Sohrabi
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.,Department of Biomedical Sciences, Macquarie University, Sydney, Australia
| | - Olivier Salvado
- CSIRO Health and Biosecurity, the Australian eHealth Research Centre, Brisbane, Queensland, Australia
| | - Michael Weinborn
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.,Australian Alzheimer's Research Foundation, Ralph and Patricia Sarich Neuroscience Research Institute, Nedlands, Western Australia, Australia.,School of Psychological Science, University of Western Australia, Crawley, Western Australia, Australia
| | - Victor L Villemagne
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia.,Department of Molecular Imaging & Therapy, Austin Health, Melbourne, Victoria, Australia.,Department of Medicine, Austin Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Colin L Masters
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Paul Maruff
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia.,CogState Ltd., Melbourne, Victoria, Australia
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Aged rats with different performances at environmental enrichment onset display different modulation of habituation and aversive memory. Neurobiol Learn Mem 2019; 161:83-91. [PMID: 30951838 DOI: 10.1016/j.nlm.2019.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/20/2019] [Accepted: 04/01/2019] [Indexed: 12/22/2022]
Abstract
A wide agreement exists that environmental enrichment (EE) is most beneficial if introduced early in life, but numerous studies reported that also aged animals remain responsive. As age-related memory and cognition impairments are not uniform, an open question is whether EE might exert different effects in animals with different age-related deficits. A 12-week EE protocol was applied to late adult rats pretested for habituation and aversive memory. Animals were classified as low (LP) and high (HP) performers according to percent exploration change in Open Field test (OF) and as impaired (I) and not impaired (NI) according to latency in Step-through Passive Avoidance test (PA). Standard housing (SH) animals pretested by OF and PA, and naïve (non-pretested) EE and SH rats were used as controls. In comparison to pretest, after the housing protocol, EE LP ameliorated while EE HP and both SH HP and LP worsened their habituation pattern. The positive influence of EE on LP was probably due to the more active interaction with and the faster adaptation to surroundings promoted by continuous, multiple stimuli provided during the enriched housing. Regarding HP, EE did not boost the basal behavior, which likely represented the maximum achievable for that age, and the post housing exploration change dropped, as in SH animals, because of the retesting. After EE, a significant percentage of NI animals became I and a significant percentage of I animals became NI. The changes evidenced in the NI group likely depended on EE-related reduction of anxiety and the consequent more efficient coping with fearful situations. This hypothesis was strengthened by the observation that naïve EE animals were almost all I. Pretested EE I rats were not influenced by the rearing condition: their behavior was comparable to SH animals' behavior and determined by retesting. In conclusion, these results demonstrated that, when applied to aging rats, EE produces different effects based on pre-housing cognitive performances. The issue needs further analyses, but the observation that not all animals are able to take advantage of EE to the same extent suggests the opportunity to design individually tailored approaches to optimize their efficacy and minimize possible unwanted consequences.
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McFall GP, McDermott KL, Dixon RA. Modifiable Risk Factors Discriminate Memory Trajectories in Non-Demented Aging: Precision Factors and Targets for Promoting Healthier Brain Aging and Preventing Dementia. J Alzheimers Dis 2019; 70:S101-S118. [PMID: 30775975 PMCID: PMC6700610 DOI: 10.3233/jad-180571] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Non-demented cognitive aging trajectories are characterized by vast level and slope differences and a spectrum of outcomes, including dementia. OBJECTIVE The goal of AD risk management (and its corollary, promoting healthy brain aging) is aided by two converging objectives: 1) classifying dynamic distributions of non-demented cognitive trajectories, and 2) identifying modifiable risk-elevating and risk-reducing factors that discriminate stable or normal trajectory patterns from declining or pre-impairment patterns. METHOD Using latent class growth analysis we classified three episodic memory aging trajectories for n = 882 older adults (baseline Mage=71.6, SD=8.9, range = 53-95, female=66%): Stable (SMA; above average level, sustained slope), Normal (NMA; average level, moderately declining slope), and Declining (DMA; below average level, substantially declining slope). Using random forest analyses, we simultaneously assessed 17 risk/protective factors from non-modifiable demographic, functional, psychological, and lifestyle domains. Within two age strata (Young-Old, Old-Old), three pairwise prediction analyses identified important discriminating factors. RESULTS Prediction analyses revealed that different modifiable risk predictors, both shared and unique across age strata, discriminated SMA (i.e., education, depressive symptoms, living status, body mass index, heart rate, social activity) and DMA (i.e., lifestyle activities [cognitive, self-maintenance, social], grip strength, heart rate, gait) groups. CONCLUSION Memory trajectory analyses produced empirical classes varying in level and slope. Prediction analyses revealed different predictors of SMA and DMA that also varied by age strata. Precision approaches for promoting healthier memory aging-and delaying memory impairment-may identify modifiable factors that constitute specific targets for intervention in the differential context of age and non-demented trajectory patterns.
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Affiliation(s)
- G. Peggy McFall
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Kirstie L. McDermott
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Roger A. Dixon
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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Balietti M, Fattorini G, Pugliese A, Marcotulli D, Bragina L, Conti F. Two Behavioral Tests Allow a Better Correlation Between Cognitive Function and Expression of Synaptic Proteins. Front Aging Neurosci 2018; 10:91. [PMID: 29670520 PMCID: PMC5893842 DOI: 10.3389/fnagi.2018.00091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 03/19/2018] [Indexed: 12/12/2022] Open
Abstract
The molecular substrate of age-associated cognitive decline (AACD) is still elusive. Evidence indicates that AACD is related to synaptic impairment in hippocampus, but different hippocampal regions play different roles, with the dorsal hippocampus (DH) associated to spatial learning, and the ventral hippocampus (VH) crucial for emotionality. If changes in hippocampal function contributes to AACD, this contribution may be reflected in alterations of synaptic protein levels. A commonly used approach to investigate this issue is western blotting. When this technique is applied to the entire hippocampus and the cognitive impairment is evaluated by a single task, changes in expression of a protein might undergo a "dilution effect", as they may occur only in a given hippocampal region. We show that two behavioral tests yield more accurate results than one test in evaluating the function of the whole rat hippocampus by studying the expression of synaptotagmin 1 (SYT1), a vesicular protein whose expression in aged hippocampus is reportedly inconsistent. Analysis of SYT1 levels in the whole hippocampus of rats selected by the Morris water maze (MWM) test only failed to highlight a difference, whereas analysis of SYT1 levels in the whole hippocampus of rats categorized by both the MWM and the step-through passive avoidance (STPA) tests demonstrated a significant increase of SYT1 level in impaired rats. These findings, besides showing that SYT1 increases in impaired aged rats, suggest that using the whole hippocampus in blotting studies may prevent false negative results only if animals are categorized with tests exploring both DH and VH.
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Affiliation(s)
- Marta Balietti
- Center for Neurobiology of Aging, INRCA, IRCCS, Ancona, Italy
| | - Giorgia Fattorini
- Center for Neurobiology of Aging, INRCA, IRCCS, Ancona, Italy.,Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Arianna Pugliese
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Daniele Marcotulli
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Luca Bragina
- Center for Neurobiology of Aging, INRCA, IRCCS, Ancona, Italy.,Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Fiorenzo Conti
- Center for Neurobiology of Aging, INRCA, IRCCS, Ancona, Italy.,Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy.,Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
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Bornschlegl M, Fischer R, Petermann F. Erfolgreiches kognitives Altern: Zusammenhang der kognitiven Leistungen mit Aktivität und Zufriedenheit. ZEITSCHRIFT FUR NEUROPSYCHOLOGIE 2016. [DOI: 10.1024/1016-264x/a000184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Zusammenfassung. Für erfolgreiches Altern sind Kognition, Zufriedenheit und tägliche Aktivitäten relevante Faktoren. In dieser Studie werden Zusammenhänge zwischen diesen Faktoren aufgedeckt. Bei 167 Senioren (60 bis 98 Jahre) wurden Aktivität und Zufriedenheit in einem Interview, Kognition durch die Neuropsychological Assessment Battery (dt. Version) erfasst. Alle Faktoren zeigen eine negative Altersentwicklung. Aktivitäten korrelieren mit allen Faktoren; insbesondere stehen Alltagsaktivitäten und kognitive Aktivitäten positiv mit Kognition im Zusammenhang, soziale Aktivität ist davon unabhängig. Die kognitiven Funktionsbereiche Aufmerksamkeit, Sprache und exekutive Funktionen variieren mit Aktivität und Zufriedenheit, Gedächtnis nur mit kognitiven Aktivitäten, Wahrnehmung ist davon unabhängig. Dies könnte bedeuten, dass kognitive Aktivitäten spezifisch mit der kognitiven Leistung und soziale Aktivitäten spezifisch mit der emotionalen Bewertung zusammenhängen und als Schutzfaktoren während der Entwicklung wirken könnten.
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Affiliation(s)
- Mona Bornschlegl
- Zentrum für Klinische Psychologie und Rehabilitation der Universität Bremen
| | - Rico Fischer
- Zentrum für Klinische Psychologie und Rehabilitation der Universität Bremen
| | - Franz Petermann
- Zentrum für Klinische Psychologie und Rehabilitation der Universität Bremen
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Tromp D, Dufour A, Lithfous S, Pebayle T, Després O. Episodic memory in normal aging and Alzheimer disease: Insights from imaging and behavioral studies. Ageing Res Rev 2015; 24:232-62. [PMID: 26318058 DOI: 10.1016/j.arr.2015.08.006] [Citation(s) in RCA: 201] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/20/2015] [Indexed: 12/30/2022]
Abstract
Age-related cognitive changes often include difficulties in retrieving memories, particularly those that rely on personal experiences within their temporal and spatial contexts (i.e., episodic memories). This decline may vary depending on the studied phase (i.e., encoding, storage or retrieval), according to inter-individual differences, and whether we are talking about normal or pathological (e.g., Alzheimer disease; AD) aging. Such cognitive changes are associated with different structural and functional alterations in the human neural network that underpins episodic memory. The prefrontal cortex is the first structure to be affected by age, followed by the medial temporal lobe (MTL), the parietal cortex and the cerebellum. In AD, however, the modifications occur mainly in the MTL (hippocampus and adjacent structures) before spreading to the neocortex. In this review, we will present results that attempt to characterize normal and pathological cognitive aging at multiple levels by integrating structural, behavioral, inter-individual and neuroimaging measures of episodic memory.
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Affiliation(s)
- D Tromp
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA - UMR 7364 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France.
| | - A Dufour
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA - UMR 7364 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France; Centre d'Investigations Neurocognitives et Neurophysiologiques (CI2N - UMS 3489 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France
| | - S Lithfous
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA - UMR 7364 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France
| | - T Pebayle
- Centre d'Investigations Neurocognitives et Neurophysiologiques (CI2N - UMS 3489 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France
| | - O Després
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA - UMR 7364 - CNRS/UDS) - 21 rue Becquerel, 67087 Strasbourg, France.
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Runge SK, Craig BM, Jim HS. Word Recall: Cognitive Performance Within Internet Surveys. JMIR Ment Health 2015; 2:e20. [PMID: 26543924 PMCID: PMC4607399 DOI: 10.2196/mental.3969] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 02/12/2015] [Accepted: 03/18/2015] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The use of online surveys for data collection has increased exponentially, yet it is often unclear whether interview-based cognitive assessments (such as face-to-face or telephonic word recall tasks) can be adapted for use in application-based research settings. OBJECTIVE The objective of the current study was to compare and characterize the results of online word recall tasks to those of the Health and Retirement Study (HRS) and determine the feasibility and reliability of incorporating word recall tasks into application-based cognitive assessments. METHODS The results of the online immediate and delayed word recall assessment, included within the Women's Health and Valuation (WHV) study, were compared to the results of the immediate and delayed recall tasks of Waves 5-11 (2000-2012) of the HRS. RESULTS Performance on the WHV immediate and delayed tasks demonstrated strong concordance with performance on the HRS tasks (ρc=.79, 95% CI 0.67-0.91), despite significant differences between study populations (P<.001) and study design. Sociodemographic characteristics and self-reported memory demonstrated similar relationships with performance on both the HRS and WHV tasks. CONCLUSIONS The key finding of this study is that the HRS word recall tasks performed similarly when used as an online cognitive assessment in the WHV. Online administration of cognitive tests, which has the potential to significantly reduce participant and administrative burden, should be considered in future research studies and health assessments.
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Affiliation(s)
- Shannon K Runge
- University of South Florida and Moffitt Cancer Center Tampa, FL United States
| | - Benjamin M Craig
- Moffitt Cancer Center and University of South Florida Tampa, FL United States
| | - Heather S Jim
- Moffitt Cancer Center and University of South Florida Tampa, FL United States
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Dixon RA, DeCarlo CA, MacDonald SWS, Vergote D, Jhamandas J, Westaway D. APOE and COMT polymorphisms are complementary biomarkers of status, stability, and transitions in normal aging and early mild cognitive impairment. Front Aging Neurosci 2014; 6:236. [PMID: 25249975 PMCID: PMC4155788 DOI: 10.3389/fnagi.2014.00236] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 08/19/2014] [Indexed: 12/18/2022] Open
Abstract
Objective: Research has reported associations among selected genetic susceptibility biomarkers and risk of (a) normal cognitive aging decrements, (b) established mild cognitive impairment (MCI), and (c) sporadic Alzheimer's disease (AD). In focusing on the transitional normal-to-early MCI phase, we examine associations among three theoretically relevant polymorphisms (APOE [rs429358, rs7412], BDNF [rs6265], COMT [rs4680]) and both baseline cognitive status (MCI vs. normal aging) and two-wave (four-year) longitudinal stability or change profiles. The latter included three profiles: (a) stable as normal aging, (b) stable or chronic impairment (MCI-to-MCI), and (c) emergence of impairment (normal-to-MCI). Method: Genotyped older adults (n = 237 at baseline; age range = 64–91; 62% women) from the Victoria Longitudinal Study were examined for (a) independent and interactive associations of three genetic polymorphisms with (b) two objectively classified cognitive status groups (not-impaired controls (NIC) and MCI) at (c) both baseline and across a two-wave (four-year) longitudinal interval. Results: First, logistic regression revealed that the presence of at least one APOE ε4 allele (the risk factor for AD) was linked to greater baseline risk of objective MCI. Second, multinomial logistic regression revealed that (a) the presence of an APOE ε4 allele was associated with an increased risk of 4-year MCI status stability (chronicity), and (b) the COMT homozygous risk genotype (G/G or Val/Val) was associated with an increased risk of both MCI-to-MCI stability (chronicity) and emerging NIC-to-MCI conversion. Discussion: Both chronicity and emergence of objectively classified early cognitive impairment may be genetically heterogeneous phenomena, with influences from a panel of both normal cognitive aging (COMT) and AD-related (APOE) polymorphisms.
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Affiliation(s)
- Roger A Dixon
- Department of Psychology, University of Alberta Edmonton, AB, Canada ; Neuroscience and Mental Health Institute, University of Alberta Edmonton, AB, Canada
| | - Correne A DeCarlo
- Department of Psychology, University of Victoria Victoria, BC, Canada
| | | | - David Vergote
- Centre for Prions and Protein Folding Diseases, University of Alberta Edmonton, AB, Canada
| | - Jack Jhamandas
- Neuroscience and Mental Health Institute, University of Alberta Edmonton, AB, Canada ; Department of Medicine (Neurology), University of Alberta Edmonton, AB, Canada
| | - David Westaway
- Neuroscience and Mental Health Institute, University of Alberta Edmonton, AB, Canada ; Centre for Prions and Protein Folding Diseases, University of Alberta Edmonton, AB, Canada
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