Assessment of Fitbit Charge 4 for sleep stage and heart rate monitoring against polysomnography and during home monitoring in Huntington's disease.

STUDY OBJECTIVES: Wearable devices that monitor sleep stages and heart rate offer the potential for longitudinal sleep monitoring in patients with neurodegenerative diseases. Sleep quality reduces with disease progression in Huntington's disease (HD). However, the involuntary movements characteristic of HD may affect the accuracy of wrist-worn devices. This study compares sleep stage and heart rate data from the Fitbit Charge 4 (FB) against polysomnography (PSG) in participants with HD. METHODS: Ten participants with manifest HD wore an FB during overnight hospital-based PSG, and 9 of these participants continued to wear the FB for 7 nights at home. Sleep stages (30-second epochs) and minute-by-minute heart rate were extracted and compared against PSG data. RESULTS: FB-estimated total sleep and wake times and sleep stage times were in good agreement with PSG, with intraclass correlations of 0.79-0.96. However, poor agreement was observed for wake after sleep onset and the number of awakenings. FB detected waking with 68.6 ± 15.5% sensitivity and 93.7 ± 2.5% specificity, rapid eye movement sleep with high sensitivity and specificity (78.7 ± 31.9%, 95.6 ± 2.3%), and deep sleep with lower sensitivity but high specificity (56.4 ± 28.8%, 95.0 ± 4.8%). FB heart rate was strongly correlated with PSG, and the mean absolute error between FB and PSG heart rate data was 1.16 ± 0.42 beats/min. At home, longer sleep and shorter wake times were observed compared with hospital data, whereas percentage sleep stage times were consistent with hospital data. CONCLUSIONS: Results suggest the potential for long-term monitoring of sleep patterns using wrist-worn wearable devices as part of symptom management in HD. CITATION: Doheny EP, Renerts K, Braun A, et al. Assessment of Fitbit Charge 4 for sleep stage and heart rate monitoring against polysomnography and during home monitoring in Huntington's disease. J Clin Sleep Med. 2024;20(7):1163-1171.

Effect of 2000 IU compared with 800 IU vitamin D on cognitive performance among adults age 60 years and older: a randomized controlled trial.

BACKGROUND: Findings on the effects of vitamin D on cognitive performance have been inconsistent and no clinical trials with detailed cognitive testing in healthy older adults have been reported. OBJECTIVES: We tested whether 2000 IU is superior to 800 IU vitamin D3/d for cognitive performance among relatively healthy older adults. DESIGN: We analyzed data on cognitive performance as the secondary outcome of a 2-y double-blind randomized controlled trial that originally investigated the effect of vitamin D3 on knee function and pain in seniors with osteoarthritis. Participants were randomly assigned to either 2000 or 800 IU vitamin D3/d. Capsules had identical appearances and taste. A total of 273 community-dwelling older adults aged ≥60 y were enrolled 6-8 wk after unilateral joint replacement. Inclusion required a baseline Mini Mental State Examination (MMSE) score of 24. We implemented a detailed 2-h cognitive test battery. The primary cognitive endpoint was the score achieved in the MMSE. Secondary endpoints included a composite score of 7 executive function tests, auditory verbal and visual design learning tests, and reaction times. RESULTS: At baseline, mean age was 70.3 y, 31.4% were vitamin D-deficient [25(OH)D <20 ng/mL], and mean ± SD MMSE score was 28.0 ± 1.5. Although the mean ± SD 25(OH)D concentrations achieved differed significantly between treatment groups at 24-mo follow-up (2000 IU = 45.1 ± 10.2 ng/mL; 800 IU = 37.5 ± 8.8 ng/mL; P < 0.0001), none of the primary or secondary endpoints of cognitive performance differed between treatment group. Results by treatment were similar for predefined subgroups of baseline 25(OH)D status (deficient compared with replete) and age (60-69 y compared with ≥70 y). CONCLUSIONS: Our study does not support a superior cognitive benefit of 2000 IU compared with 800 IU vitamin D/d among relatively healthy older adults over a 24-mo treatment period. This trial was registered at clinicaltrials.gov as NCT00599807.