Interaction between the progression of Alzheimer's disease and fractal degradation

P, Li; Yu, Lei; Yang, Jingyun; Lo, Men Tzung; Hu, Chelsea; Buchman, Aron S.; Bennett, David A.; Hu, Kun

doi:10.1016/j.neurobiolaging.2019.08.023

Cited by 23 publications

(46 citation statements)

References 57 publications

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“…On the basis of the consistent difference between complexity during the 6MWT vs. resting condition, our results moreover show that a decreased exponent α during the 6MWT at the beginning of the PR program was associated with lower functional improvement (6MWT distance) in response to PR (Figure 3). This main result is consistent with the literature showing that a decreased complexity in several physiological signals and clinical conditions is associated with different poor outcomes, such as decreased cognitive function (Yang et al, 2013), increased risk of falls (Zhou et al, 2017), bad outcome after hospitalization (Tang et al, 2015), development of Alzheimer's disease (Li et al, 2019b), and more generally an increased mortality risk (Mäkikallio et al, 1999;Batchinsky et al, 2007;Li et al, 2019a;Raichlen et al, 2019). The fact that the association between complexity and response to PR was only significant when complexity was assessed during perturbation (6MWT) is indeed consistent with previous results reported by Zhou et al (2017): this study addressed the risk of falls in the elderly and showed that only the complexity of postural sway under dualtask perturbation was associated with the risk of falls in the upcoming months.…”

Section: Only Complexity Measured Under Perturbation Relates To the Potential Of Functional Improvement Throughout Prsupporting

confidence: 91%

“…Indeed, this association is mainly an indirect one, based on cross-sectional studies showing a reduced complexity in groups of patients and in several medical conditions compared to healthy individuals ( Vaillancourt and Newell, 2002 ; Carvalho et al, 2011 ; Manor and Lipsitz, 2013 ; Dames et al, 2014 ; Li et al, 2019b ). Moreover, considering that adaptive capacity is defined as the capacity to manage perturbations, it is quite irrelevant for most studies to assess complexity in baseline situations without evaluating the system’s response to acute or chronic perturbations ( Ideker et al, 2001 ).…”

Section: Introductionmentioning

confidence: 99%

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Adaptive Capacities and Complexity of Heart Rate Variability in Patients With Chronic Obstructive Pulmonary Disease Throughout Pulmonary Rehabilitation

Hognon

Héraud²,

Varray

et al. 2021

Front. Physiol.

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IntroductionThe complexity of bio-signals, like R-R intervals, is considered a reflection of the organism’s capacity to adapt. However, this association still remains to be consolidated. We investigated whether the complexity of R-R intervals at rest and during perturbation [6-minute walking test (6MWT)], yielded information regarding adaptive capacities in Chronic Obstructive Pulmonary Disease (COPD) patients during pulmonary rehabilitation (PR).MethodsIn total, 23 COPD patients (64 ± 8 years, with forced expiratory volume in 1 s of 55 ± 19% predicted) were tested three times at the start (T1), middle (T2), and end (T3) of 4 weeks PR. Each time, R-R intervals were measured at rest and during 6MWT. The complexity of R-R intervals was assessed by evenly spaced Detrended Fluctuations Analysis and evaluated by the fractal exponent α and deviation from maximal complexity |1-α|.ResultsThe 6MWT distance was significantly increased at T2 and T3 compared to T1. Neither α nor |1-α| at rest and during perturbation significantly changed throughout PR, nor were they consistently associated with 6MWT distances at each time. Throughout the PR program, complexity during the 6MWT was significantly lower compared to the rest. The level of α during 6MWT at T1 was positively correlated with the improvement of the 6MWT distance throughout the PR program.DiscussionReduced complexity in COPD patients during acute perturbation at the beginning of PR supports a decreased improvement of the 6MWT distance throughout PR. This result seems consistent with the notion that the complexity reflects the patients’ adaptive capacities and could therefore become a clinical indicator in an applied perspective.

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Section: Only Complexity Measured Under Perturbation Relates To the Potential Of Functional Improvement Throughout Prsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Adaptive Capacities and Complexity of Heart Rate Variability in Patients With Chronic Obstructive Pulmonary Disease Throughout Pulmonary Rehabilitation

Hognon

Héraud²,

Varray

et al. 2021

Front. Physiol.

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“…As secondary analyses, we also assessed longitudinal changes of circadian measures and the longitudinal change in global cognition simultaneously using bivariate linear mixed-effects models, for which the covariance structure of the individualspecific random slopes captured correlations between the changes. 21 The corresponding two residuals were also allowed to covary with each other to allow better model fit. Positive or negative covariance between the individual-specific slopes of circadian metrics and cognition would indicate that they changed in the same or opposite direction over time.…”

Section: Discussionmentioning

confidence: 99%

Circadian disturbances in Alzheimer's disease progression: a prospective observational cohort study of community-based older adults

Gao

Gaba

et al. 2020

The Lancet Healthy Longevity

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101

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Background Circadian disturbances are commonly seen in people with Alzheimer's disease and have been reported in individuals without symptoms of dementia but with Alzheimer's pathology. We aimed to assess the temporal relationship between circadian disturbances and Alzheimer's progression. MethodsWe did a prospective cohort study of 1401 healthy older adults (aged >59 years) enrolled in the Rush Memory and Aging Project (Rush University Medical Center, Chicago, IL, USA) who had been followed up for up to 15 years. Participants underwent annual assessments of cognition (with a battery of 21 cognitive performance tests) and motor activities (with actigraphy). Four measures were extracted from actigraphy to quantify daily and circadian rhythmicity, which were amplitude of 24-h activity rhythm, acrophase (representing peak activity time), interdaily stability of 24-h activity rhythm, and intradaily variability for hourly fragmentation of activity rhythm. We used Cox proportional hazards models and logistic regressions to assess whether circadian disturbances predict an increased risk of incident Alzheimer's dementia and conversion of mild cognitive impairment to Alzheimer's dementia. We used linear mixed-effects models to investigate how circadian rhythms changed longitudinally and how the change integrated to Alzheimer's progression. FindingsParticipants had a median age of 81•8 (IQR 76•3-85•7) years. Risk of developing Alzheimer's dementia was increased with lower amplitude (1 SD decrease, hazard ratio [HR] 1•39, 95% CI 1•19-1•62) and higher intradaily variability (1 SD increase, 1•22, 1•04-1•43). In participants with mild cognitive impairment, increased risk of Alzheimer's dementia was predicted by lower amplitude (1 SD decrease, HR 1•46, 95% CI 1•24-1•72), higher intradaily variability (1 SD increase, 1•36, 1•15-1•60), and lower interdaily stability (1 SD decrease, 1•21, 1•02-1•44). A faster transition to Alzheimer's dementia in participants with mild cognitive impairment was predicted by lower amplitude (1 SD decrease, odds ratio [OR] 2•08, 95% CI 1•53-2•93), increased intradaily variability (1 SD increase, 1•97, 1•43-2•79), and decreased interdaily stability (1 SD decrease, 1•35, 1•01-1•84). Circadian amplitude, acrophase, and interdaily stability progressively decreased over time, and intradaily variability progressively increased over time. Alzheimer's progression accelerated these aging effects by doubling or more than doubling the annual changes in these measures after the diagnosis of mild cognitive impairment, and further doubled them after the diagnosis of Alzheimer's dementia. The longitudinal change of global cognition positively correlated with the longitudinal changes in amplitude and interdaily stability and negatively correlated with the longitudinal change in intradaily variability. Interpretation Our results indicate a link between circadian dysregulation and Alzheimer's progression, implying either a bidirectional relation or shared common underlying pathophysiological mechanisms.

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“…This finding supports the theory that fractal regulation reflects the complexity of physiological control. And conversely, the degradation suggests a reduced complexity in the system; thus the system becomes less adaptive to perturbations and more vulnerable to catastrophic events (26,33).…”

Section: Discussionmentioning

confidence: 99%

More random motor activity fluctuations predict incident frailty, disability, and mortality

Lim

Gao

et al. 2019

Sci. Transl. Med.

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Mobile healthcare increasingly relies on analytical tools that can extract meaningful information from ambulatory physiological recordings. We tested whether a nonlinear tool of fractal physiology could predict long-term health consequences in a large, elderly cohort. Fractal physiology is an emerging field that aims to study how fractal temporal structures in physiological fluctuations generated by complex physiological networks can provide important information about system adaptability. We assessed fractal temporal correlations in the spontaneous fluctuations of ambulatory motor activity of 1275 older participants at baseline, with a follow-up period of up to 13 years. We found that people with reduced temporal correlations (more random activity fluctuations) at baseline had increased risk of frailty, disability, and all-cause death during follow-up. Specifically, for 1-SD decrease in the temporal activity correlations of this studied cohort, the risk of frailty increased by 31%, the risk of disability increased by 15 to 25%, and the risk of death increased by 26%. These incidences occurred on average 4.7 years (frailty), 3 to 4.2 years (disability), and 5.8 years (death) after baseline. These observations were independent of age, sex, education, chronic health conditions, depressive symptoms, cognition, motor function, and total daily activity. The temporal structures in daily motor activity fluctuations may contain unique prognostic information regarding wellness and health in the elderly population.

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Interaction between the progression of Alzheimer's disease and fractal degradation

Cited by 23 publications

References 57 publications

Adaptive Capacities and Complexity of Heart Rate Variability in Patients With Chronic Obstructive Pulmonary Disease Throughout Pulmonary Rehabilitation

Adaptive Capacities and Complexity of Heart Rate Variability in Patients With Chronic Obstructive Pulmonary Disease Throughout Pulmonary Rehabilitation

Circadian disturbances in Alzheimer's disease progression: a prospective observational cohort study of community-based older adults

More random motor activity fluctuations predict incident frailty, disability, and mortality

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