In preclinical research on Alzheimer’s disease and related tauopathies, tau phosphorylation analysis is routinely employed in both cellular and animal models. However, recognizing the sensitivity of tau phosphorylation to various extrinsic factors, notably temperature, is vital for experimental accuracy. Hypothermia can trigger tau hyperphosphorylation, while hyperthermia leads to its dephosphorylation. Nevertheless, the rapidity of tau phosphorylation in response to unintentional temperature variations remains unknown. In cell cultures, the most significant temperature change occurs when the cells are removed from the incubator before harvesting, and in animal models, during anesthesia prior to euthanasia. In this study, we investigate the kinetics of tau phosphorylation in N2a and SH-SY5Y neuronal cell lines, as well as in mice exposed to anesthesia. We observed changes in tau phosphorylation within the few seconds upon transferring cell cultures from their 37°C incubator to room temperature conditions.However, cells placed directly on ice post-incubation exhibited negligible phosphorylation changes. In vivo, isoflurane anesthesia rapidly resulted in tau hyperphosphorylation within the few seconds needed to lose the pedal withdrawal reflex in mice. These findings emphasize the critical importance of preventing temperature variation in researches focused on tau. To ensure accurate results, we recommend avoiding anesthesia before euthanasia and promptly placing cells on ice after removal from the incubator. By controlling temperature fluctuations, the reliability and validity of tau phosphorylation studies can be significantly enhanced.

Background: Gait speed is associated with a higher prevalence of balance disorders in older adults residing at high altitudes. This study investigated this association in older adults from 12 high-altitude Andean Peruvian communities. Methods: We performed a secondary data analysis from an analytical cross-sectional study of adults >60 years of age, residing in 12 high-altitude Andean Peruvian communities, enrolled between 2013 and 2019. The exposure and outcome variables were gait speed (categorized in tertiles), and balance disorders (defined as a functional reach value of ≤20.32 cm), respectively. We built generalized linear models of the Poisson family with a logarithmic link function and robust variances, and estimated crude prevalence ratios (cPR) and adjusted prevalence ratios (aPR) with 95% confidence intervals (CIs). Results: We analyzed 418 older adults; 38.8% (n=162) were male, and the mean age was 73.2±6.9 years. The mean gait speed and functional reach were 0.66±0.24 m/s and 19.9±6.48 cm, respectively. In the adjusted regression model, the intermediate (aPR=1.88; 95% CI, 1.39–2.55; p<0.001) and low (aPR=2.04; 95% CI, 1.51–2.76; p<0.001) tertiles of gait speed were associated with a higher prevalence of balance disorders. Conclusion The intermediate and low tertiles of gait speed were associated with a higher prevalence of balance disorders among older adult residents of 12 high-altitude Andean communities. We recommend further research on the behavior of this association to propose interventions for these vulnerable groups and reduce the impact of geriatric conditions.