Association du rythme circadien avec des troubles cognitifs légers chez les travailleurs masculins atteints de pneumoconiose à Hong Kong : un croisement

Mild cognitive impairment (MCI) is a cognitive decline greater than expected for an individual's age and education level but without notable interference in daily activities27. It is a preclinical status between normal cognition to cognitive impairment. The CMMSE was used to measure the cognitive function of the study participants. The CMMSE has been translated and validated by Chiu et al. to assess dementia among Hong Kong Chinese28, which contains 30 items to measure various cognitive domains, including orientation, registration, attention and calculation, immediate and short-term recall, and language, with a score ranging from 0 to 30. A lower CMMSE score indicates a worse cognitive function of the participant. We adopted the cut-off levels of CMMSE proposed in a previous study (2012)." href="/articles/s41598-023-28832-5#ref-CR29" id="ref-link-section-d63416991e625"29 to define the cognitive status, i.e., 27–30, 21–26, 0–20 were mutually exclusively categorized as normal cognition, MCI, and cognitive impairment (which also means "moderate-severe cognitive impairment"), respectively./p> 7th, 7th-2nd, and ≤ 2nd percentile was determined as normal cognition, MCI, and cognitive impairment, respectively32. Since no percentile cutoff scores were reported for subjects < 65 years old in the manual, subjects in this age stratum were referred to the percentile scores of the 65–69 age stratum in this study./p>

Each pneumoconiosis worker and community subject continuously wore a GENEActiv Original (Activinsights Company, UK) device on his non-dominant wrist for 168 h without removal, even during sleep or bathing (measurement frequency 100 Hz, sampling rate corresponding to 1 min). The assessment of circadian rhythm parameters had been described previously33. The actigraphy detects and records movements in three mutually vertical axes (x, y, and z) and real-time skin temperature. A gravity-subtracted sum of vector magnitudes (SVM) was automatically calculated with data of the three axes (x, y, and z) and a formula defined by the manufacturer: SVMg s = [(x2 + y2 + z2)½—1 g]." href="/articles/s41598-023-28832-5#ref-CR34" id="ref-link-section-d63416991e665"34. Non-wearing time was determined by reviewing the activity records outputted from the GENEActiv software and self-reported by the interviewees. The non-wearing periods should present low and steady SVM readings. For each participant, the data of non-wearing periods were excluded from the calculation of their parameters. The recordings lasted from 5 to 7 consecutive days, including a weekend. If the sum length of wearing was less than 120 h (5/7 of 168 h), the wearing was considered incomplete, and its data were not analyzed./p> 5), waist circumference, and handgrip strength. The covariates were selected based on the conceptual definition of confounding and referred to previous literature with similar study purposes./p>

This study has several limitations. First, the cross-sectional design of this study may limit us from causal inference. However, this study added value to the scientific literature as evidence of circadian rhythm and the cognitive outcome is very limited in pneumoconiosis patients. Second, sixty community subjects in the study were recruited between June 23 to July 09, 2020, just after the 2nd wave of the COVID-19 outbreak in Hong Kong (2020)." href="/articles/s41598-023-28832-5#ref-CR46" id="ref-link-section-d63416991e4184"46. The possible physical inactivity due to sustained quarantine and social distancing47 may adversely influence participants' circadian rhythm. We performed a sensitivity analysis excluding the community subjects recruited within this period. A significantly decreased amplitude was observed in pneumoconiosis patients compared to that of the community subjects (as shown in Supplementary Table S2). Thus, the overall circadian activity of the community referents may be underestimated. However, we expected this would have biased our findings toward the null. Third, we used medians as cut-offs for each circadian rhythm parameter because there are no standard criteria to define weak and robust circadian rhythm. Meanwhile, the sample size restricted us from further dividing participants into tertiles or quartiles of circadian rhythm parameters to investigate the biological gradient (dose–response) of circadian disruption. According to their self-reported disease history, there were no patients with any lung diseases in our community referents. Thus, we could not compare the major outcomes between community residents with or without other lung diseases. We used the composite outcome of MCI plus cognitive impairment as the primary outcome to improve statistical power. Finally, all our study participants were men, so the generalization to the whole population, including women, could be limited./p> (2019)./p>

(2012)./p>./p> (2020)./p>