Applying time series analyses on continuous accelerometry data—A clinical example in older adults with and without cognitive impairment

Introduction Many clinical studies reporting accelerometry data use sum score measures such as percentage of time spent in moderate to vigorous activity which do not provide insight into differences in activity patterns over 24 hours, and thus do not adequately depict circadian activity patterns. Here, we present an improved functional data analysis approach to model activity patterns and circadian rhythms from accelerometer data. As a use case, we demonstrated its application in patients with mild cognitive impairment (MCI) and age-matched healthy older volunteers (HOV). Methods Data of two studies were pooled for this analysis. Following baseline cognitive assessment participants were provided with accelerometers for seven consecutive days. A function on scalar regression (FoSR) approach was used to analyze 24 hours accelerometer data. Results Information on 48 HOV (mean age 65 SD 6 years) and 18 patients with MCI (mean age 70, SD 8 years) were available for this analysis. MCI patients displayed slightly lower activity in the morning hours (minimum relative activity at 6:05 am: -41.3%, 95% CI -64.7 to -2.5%, p = 0.031) and in the evening (minimum relative activity at 21:40 am: -48.4%, 95% CI -68.5 to 15.4%, p = 0.001) as compared to HOV after adjusting for age and sex. Discussion Using a novel approach of FoSR, we found timeframes with lower activity levels in MCI patients compared to HOV which were not evident if sum scores of amount of activity were used, possibly indicating that changes in circadian rhythmicity in neurodegenerative disease are detectable using easy-to-administer accelerometry. Clinical trials Effects of Brain Stimulation During Nocturnal Sleep on Memory Consolidation in Patients With Mild Cognitive Impairments, ClinicalTrial.gov identifier: NCT01782391. Effects of Brain Stimulation During a Daytime Nap on Memory Consolidation in Patients With Mild Cognitive Impairment, ClinicalTrial.gov identifier: NCT01782365.

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Applying time series analyses on continuous accelerometry data – a clinical example in older adults with and without cognitive impairment

10.1101/2020.03.24.20042226 ◽

2020 ◽

Author(s):

Torsten Rackoll ◽

Konrad Neumann ◽

Sven Passmann ◽

Ulrike Grittner ◽

Nadine Külzow ◽

...

Keyword(s):

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Brain Stimulation ◽

Memory Consolidation ◽

Activity Patterns ◽

Accelerometer Data ◽

Activity Data ◽

Link Type ◽

Early Afternoon ◽

The Impact

AbstractIntroductionCurrent analysis approaches of accelerometry data use sum score measures which do not provide insight in activity patterns over 24 hours, and thus do not adequately depict circadian activity patterns. Here, we used a functional approach to analyze accelerometer data that models activity pattern and circadian rhythm. As a test case, we demonstrated its application in patients with mild cognitive impairment (MCI) and age-matched healthy older volunteers (HOV). Moreover, we assessed the impact of chronotype on distribution of activity data.MethodsData of two studies were pooled for this analysis. Following baseline cognitive assessment participants were provided with accelerometers for seven consecutive days. A function on scalar regression (FoSR) approach was used to analyze 24 hours accelerometer data. In a second step, analyses were controlled for chronotype using the German version of the morningness-eveningness questionnaire (d-MEQ).ResultsInformation on 47 HOV (mean age 66 SD 6 years) and 13 patients with MCI (mean age 69, SD 8 years) were available for this analysis. MCI patients displayed slightly higher activity in the morning hours as compared to HOV (maximum relative activity at 7:35 am: 75.6%, 95% CI 2.6 to 200.4%, p = 0.031). After controlling for d-MEQ, disturbed activity patterns were found in MCI of intermediate or evening chronotype, compared to HOV, i.e., MCI presented with higher activities in the morning hours (peak at 8:40 am: 357.6%, 95% CI 92.9 to 985.1, p < 0.001) and early afternoon hours (peak at 1:40 pm: 401.8%, 95% CI 63.9 to 1436.4, p < 0.001).DiscussionUsing a novel approach of FoSR, we found timeframes with higher activity levels in MCI patients compared to HOV which were not evident if sum scores of amount of activity were used. In addition, we found that previously described activity patterns as a function of chronotype swere altered in MCI patients, possibly indicating that changes in circadian rhythmicity in neurodegenerative disease are detectable using easy-to-administer accelerometry.Clinical TrialsEffects of Brain Stimulation During Nocturnal Sleep on Memory Consolidation in Patients With Mild Cognitive Impairments, https://clinicaltrials.gov/ct2/show/NCT01782391?term=NCT01782391&rank=1,ClinicalTrial.gov identifier: NCT01782391Effects of Brain Stimulation During a Daytime Nap on Memory Consolidation in Patients With Mild Cognitive Impairment,https://clinicaltrials.gov/ct2/show/NCT01782365?term=NCT01782365&rank=1,ClinicalTrial.gov identifier: NCT01782365

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Transcranial stimulation enhances memory-relevant sleep oscillations and their functional coupling in mild cognitive impairment

10.1101/095588 ◽

2016 ◽

Author(s):

Julia Ladenbauer ◽

Josef Ladenbauer ◽

Nadine Külzow ◽

Rebecca de Boor ◽

Elena Avramova ◽

...

Keyword(s):

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Memory Consolidation ◽

Declarative Memory ◽

Activity Patterns ◽

Functional Coupling ◽

Dependent Manner ◽

Sleep State ◽

Sleep Physiology ◽

Spindle Power

AbstractAlzheimer’s disease (AD) not only involves loss of memory functions but also prominent deterioration of sleep physiology, already evident in the stage ofmild cognitive impairment(MCI). Cortical slow oscillations (SO, 0.5-1 Hz) and thalamo-cortical spindle activity (12-15 Hz) during sleep, and their temporal coordination, are considered critical for memory formation. We investigated the potential of slow oscillatory transcranial direct current stimulation (so-tDCS), applied during a daytime nap in a sleep state-dependent manner, to modulate these activity patterns and sleep-related memory consolidation in 16 patients with MCI.Stimulation significantly increased overall SO and spindle power, amplified spindle power during SO up-phases, and led to stronger synchronization between SO and spindle power fluctuations in electroencephalographic recordings. Moreover, visual declarative memory was improved by so-tDCS compared to sham stimulation, associated with stronger synchronization. These findings indicate a well-tolerated therapeutic approach for disordered sleep physiology and deficits in memory consolidation in MCI patients.

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