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Cassady KE, Chen X, Adams JN, Harrison TM, Zhuang K, Maass A, Baker S, Jagust W. Effect of Alzheimer's Pathology on Task-Related Brain Network Reconfiguration in Aging. J Neurosci 2023; 43:6553-6563. [PMID: 37604690 PMCID: PMC10513069 DOI: 10.1523/jneurosci.0023-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 08/02/2023] [Accepted: 08/06/2023] [Indexed: 08/23/2023] Open
Abstract
Large-scale brain networks undergo widespread changes with older age and in neurodegenerative diseases such as Alzheimer's disease (AD). Research in young adults (YA) suggest that the underlying functional architecture of brain networks remains relatively consistent between rest and task states. However, it remains unclear whether the same is true in aging and to what extent any changes may be related to accumulation of AD pathology such as β-amyloid (Aβ) and tau. Here, we examined age-related differences in functional connectivity (FC) between rest and an object-scene mnemonic discrimination task using fMRI in young and older adults (OA; both females and males). We used an a priori episodic memory network (EMN) parcellation scheme associated with object and scene processing, that included anterior-temporal regions and posterior-medial regions. We also used positron emission topography to measure Aβ and tau in older adults. The correlation between rest and task FC (i.e., FC similarity) was reduced in older compared with younger adults. Older adults with lower FC similarity in EMN had higher levels of tau in the same EMN regions and performed worse during object, but not scene, trials during the fMRI task. These findings link AD pathology, particularly tau, to a less stable functional architecture in memory networks. They also suggest that smaller changes in FC organization between rest and task states may facilitate better performance in older age. Interpretations are limited by methodological factors related to different acquisition directions and durations between rest and task scans.SIGNIFICANCE STATEMENT The brain's large-scale network organization is relatively consistent between rest and task states in young adults (YA). We found that memory networks in older adults (OA) were less correlated between rest and (memory) task states compared with young adults. Older adults with less correlated brain networks also had higher levels of Alzheimer's disease (AD) pathology in the same regions, suggesting that a less stable network architecture may reflect the early evolution of AD. Older adults with less correlated brain networks also performed worse during the memory task suggesting that more similar network organization between rest and task states may facilitate better performance in older age.
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Affiliation(s)
- Kaitlin E Cassady
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
| | - Xi Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
| | - Jenna N Adams
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
| | - Theresa M Harrison
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
| | - Kailin Zhuang
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
| | - Anne Maass
- German Center for Neurodegenerative Disease, 39120 Magdeburg, Germany
| | - Suzanne Baker
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - William Jagust
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720
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Zhuang K, Chen X, Cassady KE, Baker SL, Jagust WJ. Metacognition, cortical thickness, and tauopathy in aging. Neurobiol Aging 2022; 118:44-54. [PMID: 35868093 PMCID: PMC9979699 DOI: 10.1016/j.neurobiolaging.2022.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 11/30/2022]
Abstract
We investigated self-rating of cognitive task performance (self-appraisal) and the difference between self-rating and actual task performance (appraisal discrepancy) in cognitively healthy older adults and their relationship with cortical thickness and Alzheimer's disease (AD) biomarkers, amyloid and tau. All participants (N = 151) underwent neuropsychological testing and 1.5T structural magnetic resonance imaging. A subset (N = 66) received amyloid-PET with [11C] PiB and tau-PET with [18F] Flortaucipir. We found that worse performers had lower self-appraisal ratings, but still overestimated their performance, consistent with the Dunning-Kruger effect. Self-appraisal rating and appraisal discrepancy revealed distinct relationships with cortical thickness and AD pathology. Greater appraisal discrepancy, indicating overestimation, was related to thinning of inferior-lateral temporal, fusiform, and rostral anterior cingulate cortices. Lower self-appraisal was associated with higher entorhinal and inferior temporal tau. These results suggest that overestimation could implicate structural atrophy beyond AD pathology, while lower self-appraisal could indicate early behavioral alteration due to AD pathology, supporting the notion of subjective cognitive decline prior to objective deficits.
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Affiliation(s)
- Kailin Zhuang
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Xi Chen
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kaitlin E Cassady
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Suzanne L Baker
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - William J Jagust
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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Cassady KE, Adams JN, Chen X, Maass A, Harrison TM, Landau S, Baker S, Jagust W. Alzheimer's Pathology Is Associated with Dedifferentiation of Intrinsic Functional Memory Networks in Aging. Cereb Cortex 2021; 31:4781-4793. [PMID: 34037210 PMCID: PMC8408467 DOI: 10.1093/cercor/bhab122] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/14/2022] Open
Abstract
In presymptomatic Alzheimer's disease (AD), beta-amyloid plaques (Aβ) and tau tangles accumulate in distinct spatiotemporal patterns within the brain, tracking closely with episodic memory decline. Here, we tested whether age-related changes in the segregation of the brain's intrinsic functional episodic memory networks-anterior-temporal (AT) and posterior-medial (PM) networks-are associated with the accumulation of Aβ, tau, and memory decline using fMRI and PET. We found that AT and PM networks were less segregated in older than that in younger adults and this reduced specialization was associated with more tau and Aβ in the same regions. The effect of network dedifferentiation on memory depended on the amount of Aβ and tau, with low segregation and pathology associated with better performance at baseline and low segregation and high pathology related to worse performance over time. This pattern suggests a compensation phase followed by a degenerative phase in the early, preclinical phase of AD.
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Affiliation(s)
- Kaitlin E Cassady
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Jenna N Adams
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Xi Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Anne Maass
- German Center for Neurodegenerative Disease, Magdeburg 39120, Germany
| | - Theresa M Harrison
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Susan Landau
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Suzanne Baker
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - William Jagust
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
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Ruitenberg MFL, Cassady KE, Reuter-Lorenz PA, Tommerdahl M, Seidler RD. Age-Related Reductions in Tactile and Motor Inhibitory Function Start Early but Are Independent. Front Aging Neurosci 2019; 11:193. [PMID: 31417396 PMCID: PMC6682653 DOI: 10.3389/fnagi.2019.00193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/15/2019] [Indexed: 11/13/2022] Open
Abstract
Aging is associated with declines in motor and somatosensory function. Some of these motor declines have been linked to age-related reductions in inhibitory function. Here we examined whether tactile surround inhibition also changes with age and whether these changes are associated with those in the motor domain. We tested a group of 56 participants spanning a wide age range (18-76 years old), allowing us to examine when age differences emerge across the lifespan. Participants performed tactile and motor tasks that have previously been linked to inter- and intra-hemispheric inhibition in the somatosensory and motor systems. The results showed that aging is associated with reductions in inhibitory function in both the tactile and motor systems starting around 40 years of age; however, age effects in the two systems were not correlated. The independent effects of age on tactile and motor inhibitory function suggest that distinct mechanisms may underlie age-related reductions in inhibition in the somatosensory and motor systems.
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Affiliation(s)
- Marit F L Ruitenberg
- Department of Experimental Psychology, Ghent University, Ghent, Belgium.,Department of Health, Medical and Neuropsychology, Leiden University, Leiden, Netherlands
| | - Kaitlin E Cassady
- Department of Psychology, University of Michigan, Ann Arbor, MI, United States
| | | | - Mark Tommerdahl
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, United States
| | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
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Ruitenberg MFL, Cassady KE. Commentary: Age Differentiation within Gray Matter, White Matter, and between Memory and White Matter in an Adult Life Span Cohort. Front Aging Neurosci 2019; 11:93. [PMID: 31057393 PMCID: PMC6482270 DOI: 10.3389/fnagi.2019.00093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 04/04/2019] [Indexed: 11/23/2022] Open
Affiliation(s)
- Marit F. L. Ruitenberg
- Department of Experimental Psychology, Ghent University, Ghent, Belgium
- *Correspondence: Marit F. L. Ruitenberg
| | - Kaitlin E. Cassady
- Department of Psychology, University of Michigan, Ann Arbor, MI, United States
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Koppelmans V, Scott JM, Downs ME, Cassady KE, Yuan P, Pasternak O, Wood SJ, De Dios YE, Gadd NE, Kofman I, Riascos R, Reuter-Lorenz PA, Bloomberg JJ, Mulavara AP, Ploutz-Snyder LL, Seidler RD. Exercise effects on bed rest-induced brain changes. PLoS One 2018; 13:e0205515. [PMID: 30308004 PMCID: PMC6181401 DOI: 10.1371/journal.pone.0205515] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 09/26/2018] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Spaceflight negatively affects sensorimotor behavior; exercise mitigates some of these effects. Head down tilt bed rest (HDBR) induces body unloading and fluid shifts, and is often used to investigate spaceflight effects. Here, we examined whether exercise mitigates effects of 70 days HDBR on the brain and if fitness and brain changes with HDBR are related. METHODS HDBR subjects were randomized to no-exercise (n = 5) or traditional aerobic and resistance exercise (n = 5). Additionally, a flywheel exercise group was included (n = 8). Exercise protocols for exercise groups were similar in intensity, therefore these groups were pooled in statistical analyses. Pre and post-HDBR MRI (structure and structural/functional connectivity) and physical fitness measures (lower body strength, muscle cross sectional area, VO2 max, body composition) were collected. Voxel-wise permutation analyses were used to test group differences in brain changes, and their associations with fitness changes. RESULTS Comparisons of exercisers to controls revealed that exercise led to smaller fitness deterioration with HDBR but did not affect brain volume or connectivity. Group comparisons showed that exercise modulated post-HDBR recovery of brain connectivity in somatosensory regions. Posthoc analysis showed that this was related to functional connectivity decrease with HDBR in non-exercisers but not in exercisers. Correlational analyses between fitness and brain changes showed that fitness decreases were associated with functional connectivity and volumetric increases (all r >.74), potentially reflecting compensation. Modest brain changes or even decreases in connectivity and volume were observed in subjects who maintained or showed small fitness gains. These results did not survive Bonferroni correction, but can be considered meaningful because of the large effect sizes. CONCLUSION Exercise performed during HDBR mitigates declines in fitness and strength. Associations between fitness and brain connectivity and volume changes, although unadjusted for multiple comparisons in this small sample, suggest that supine exercise reduces compensatory HDBR-induced brain changes.
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Affiliation(s)
- Vincent Koppelmans
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Psychiatry, University of Utah, Salt Lake City, Utah, United States of America
| | - Jessica M. Scott
- Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Universities Space Research Association, NASA Johnson Space Center, Houston, Texas, United States of America
| | | | - Kaitlin E. Cassady
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peng Yuan
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Ofer Pasternak
- Department of Psychiatry and Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Scott J. Wood
- NASA Johnson Space Center, Houston, Texas, United States of America
| | | | | | - Igor Kofman
- KBRwyle, Houston, Texas, United States of America
| | - Roy Riascos
- The University of Texas Health Science Center, Houston, Texas, United States of America
| | - Patricia A. Reuter-Lorenz
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
- Neuroscience Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | | | | | - Lori L. Ploutz-Snyder
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Universities Space Research Association, NASA Johnson Space Center, Houston, Texas, United States of America
| | - Rachael D. Seidler
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Psychology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, Florida, United States of America
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Koppelmans V, Mulavara AP, Yuan P, Cassady KE, Cooke KA, Wood SJ, Reuter-Lorenz PA, De Dios YE, Stepanyan V, Szecsy DL, Gadd NE, Kofman I, Scott JM, Downs ME, Bloomberg JJ, Ploutz-Snyder L, Seidler RD. Exercise as potential countermeasure for the effects of 70 days of bed rest on cognitive and sensorimotor performance. Front Syst Neurosci 2015; 9:121. [PMID: 26388746 PMCID: PMC4558429 DOI: 10.3389/fnsys.2015.00121] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 08/17/2015] [Indexed: 12/14/2022] Open
Abstract
Background: Spaceflight has been associated with changes in gait and balance; it is unclear whether it affects cognition. Head down tilt bed rest (HDBR) is a microgravity analog that mimics cephalad fluid shifts and body unloading. In consideration of astronaut’s health and mission success, we investigated the effects of HDBR on cognition and sensorimotor function. Furthermore, we investigated if exercise mitigates any cognitive and sensorimotor sequelae of spaceflight. Method: We conducted a 70-day six-degree HDBR study in 10 male subjects who were randomly assigned to a HDBR supine exercise or a HDBR control group. Cognitive measures (i.e., processing speed, manual dexterity, psychomotor speed, visual dependency, and 2D and 3D mental rotation) and sensorimotor performance (functional mobility (FMT) and balance performance) were collected at 12 and 8 days pre-HDBR, at 7, 50, and 70 days in HDBR, and at 8 and 12 days post-HDBR. Exercise comprised resistance training, and continuous and high-intensity interval aerobic exercise. We also repeatedly assessed an outside-of-bed rest control group to examine metric stability. Results: Small practice effects were observed in the control group for some tasks; these were taken into account when analyzing effects of HDBR. No significant effects of HDBR on cognition were observed, although visual dependency during HDBR remained stable in HDBR controls whereas it decreased in HDBR exercise subjects. Furthermore, HDBR was associated with loss of FMT and standing balance performance, which were almost fully recovered 12 days post-HDBR. Aerobic and resistance exercise partially mitigated the effects of HDBR on FMT and accelerated the recovery time course post-HDBR. Discussion: HDBR did not significantly affect cognitive performance but did adversely affect FMT and standing balance performance. Exercise had some protective effects on the deterioration and recovery of FMT.
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Affiliation(s)
| | - Ajitkumar P Mulavara
- NASA Johnson Space Center Houston, TX, USA ; Universities Space Research Association Houston, TX, USA
| | - Peng Yuan
- School of Kinesiology, University of Michigan Ann Arbor, MI, USA
| | - Kaitlin E Cassady
- School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA
| | - Katherine A Cooke
- School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA
| | - Scott J Wood
- NASA Johnson Space Center Houston, TX, USA ; Department of Psychology, Azusa Pacific University Azusa, CA, USA
| | - Patricia A Reuter-Lorenz
- Department of Psychology, University of Michigan Ann Arbor, MI, USA ; Neuroscience Program, University of Michigan Ann Arbor, MI, USA
| | - Yiri E De Dios
- Wyle Science, Technology and Engineering Group Houston, TX, USA
| | | | | | - Nichole E Gadd
- Wyle Science, Technology and Engineering Group Houston, TX, USA
| | - Igor Kofman
- Wyle Science, Technology and Engineering Group Houston, TX, USA
| | | | - Meghan E Downs
- Department of Health and Human Performance, University of Houston Houston, TX, USA
| | | | - Lori Ploutz-Snyder
- NASA Johnson Space Center Houston, TX, USA ; Universities Space Research Association Houston, TX, USA
| | - Rachael D Seidler
- School of Kinesiology, University of Michigan Ann Arbor, MI, USA ; Department of Psychology, University of Michigan Ann Arbor, MI, USA ; Neuroscience Program, University of Michigan Ann Arbor, MI, USA ; Institute of Gerontology, University of Michigan Ann Arbor, MI, USA
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