Neurofilament light chain (NfL) is a novel biomarker of neurodegenerative diseases. It is detectable in the peripheral blood, allowing low-invasive assessment of early signs of neurodegeneration. The level of NfL gradually increases with age; however, what other factors affect it remains unclear. The present study examined the association between blood NfL level and renal function among healthy participants undergoing a health check (n = 43, serum NfL) and patients with diabetes mellitus (n = 188, plasma NfL). All participants were 60 years of age or older; none were diagnosed with dementia. In each group, levels of blood NfL and serum creatinine significantly correlated (coefficient r = 0.50, 0.56). These associations remained statistically significant even after adjustment for age, sex, and body mass index. These findings indicate that blood NfL level might be partially affected by renal function. We recommend measuring renal function for a more precise evaluation of neuroaxonal damage, in particular, among older adults.

Background: There is a difference in the neuronal state of individuals. However, this has not been taken into consideration in most intervention studies. Recent advances in analytical technologies in hematological examination enabled us to evaluate neuronal states in a relatively convenient manner. Objective: Using these advanced technologies, we aimed to investigate whether cognitive intervention effects vary as a function of levels of blood-based biomarkers, such as neurofilament light chain (NfL), since plasma NfL could be a biomarker of neurodegenerative diseases including Alzheimer's disease. Methods: In this study, we employed a group conversation-based intervention methodology named Photo-Integrated Conversation Moderated by Robots (PICMOR), which has been shown to improve verbal fluency in older adults. To examine the possibility of varying effects of this intervention method according to the neuronal state of each individual, we conducted a randomized controlled trial (UMIN Clinical Trials Registry number: UMIN000036599) and investigated how longitudinal changes in cognitive performance, such as verbal fluency, vary with the NfL level measured at the baseline. Results: As the main result, positive intervention effects of PICMOR on verbal fluency were observed in individuals with lower level of NfL, which indicate a relatively intact neuronal state, whereas negative intervention effects were identified in individuals with higher NfL level. Conclusion: Our findings suggest that cognitive intervention effects vary depending on level of Nfl in the plasma. Thus, future intervention studies should take into account the neuronal status of the participants to examine intervention effects.

Background: Patients with diabetes are at a higher risk for cognitive decline. Thus, biomarkers that can provide early and simple detection of cognitive decline are required. Neurofilament light chain (NfL) is a cytoskeletal protein that constitutes neural axons. Plasma NfL levels are elevated when neurodegeneration occurs. Here, we investigated whether plasma NfL levels were associated with cognitive decline in patients with type 2 diabetes. Method: This study included 183 patients with type 2 diabetes who visited Osaka University Hospital. All participants were tested for cognitive function using the Mini-Mental State Examination (MMSE) and the Rivermead Behavioural Memory Test (RBMT). NfL levels were analysed in the plasma and the relationship between NfL and cognitive function was examined. Results: Lower RBMT-standardized profile scores (SPS) or MMSE scores correlated with higher plasma NfL levels (one-way analysis of variance: MMSE, P = 0.0237; RBMT-SPS, P = 0.0001). Furthermore, plasma NfL levels (β = À0.34, P = 0.0005) and age (β = À0.19, P = 0.016) were significantly associated with the RBMT score after multivariable regression adjustment. Conclusions: Plasma NfL levels were correlated with mild cognitive decline which is detected by the RBMT but not the MMSE in patients with type 2 diabetes. This suggests that plasma NfL levels may provide a valuable clinical tool for identifying mild cognitive decline in patients with diabetes.

This retrospective cohort study investigates the association between the incidence of sleep problems and changes in digital media use among university students during the COVID-19 pandemic. It used data from annual health check-ups performed at a Japanese university in 2019 and 2020. Students undergoing these check-ups were identified to respond to questions about sleep problems, digital media use, breakfast and exercise habits, and stress. In total, 3,869 students were included in the analysis. The association between the incidence of sleep problems in 2020 and the changes in digital media use between 2019 and 2020 was assessed using logistic regression models. The rate of long digital media use (≥ 2 hours) in 2019 was 42.6%, while in 2020 it was 53.6%. Incidence of sleep problems was observed in 244 students (6.3%) in 2020. There were 786 students (20.3%) who used digital media for ≤ 2 h in 2019 and ≥ 2 h in 2020. From the sample, 66 students (8.4%) reported incidence of sleep problems in 2020. Additionally, those respondents who specifically reported increased digital media use between 2019 and 2020 (increased use) where at greater risk (OR: 1.76; 95% CI: 1.21, 2.55) of reporting sleep problems in 2020, even after controlling for other study variables. Thus, this study provides evidence that the incidence of sleep problems has had a significant association with an increase in digital media use among university students throughout the COVID-19 pandemic. These findings highlight the importance of ensuring appropriate digital media use among students for improved quality of sleep.