Introduction. Core body temperature (CBT) is a firmly regulated parameter of human physiology and an important indicator of human health. Furthermore, because CBT is underlying rhythmic oscillations controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus, it is a vital and accepted measurement of the circadian rhythm (CR). Disturbances in CBT and CR are potential early biomarkers for neurodegeneration. Dysfunction in temperature and circadian rhythm regulation is widely implicated in some of the most common neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and the less common Narcolepsy Type 1 (NT1). Compared with healthy individuals, patients with neurodegenerative diseases may exhibit abnormalities in the circadian cycle and thermoregulatory control. This study aims to determine the disease-specific profile of circadian rhythm and thermoregulation in patients with neurodegenerative disorders (AD, PD, and NT1) compared to healthy individuals.
Methods. 5 AD, 20 PD, 20 NT1 patients, and 74 healthy controls were included in the study. Core body (CBT), proximal (apical, clavicular, and upper arm) and distal (wrist) skin temperatures, actigraphy, heart rate (HR), and ambient temperature were measured over 72 hr under free-living, non-invasive conditions. Participants were asked to maintain a diary regarding their sleeping, eating, and physical activity habits.
Statistics: To compare each patient group with age-, sex-, and body mass index-matched healthy controls cosinor analysis, and one-way analysis of variance (ANOVA) were performed.
Results. Compared to healthy controls, CBT showed significantly reduced values in NT1 and PD patients during the day, whereas in AD, distal skin temperatures were elevated during the day. Circadian CBT amplitude showed a trend towards reduced values in NT1 and PD patients compared to controls. Furthermore, the temperature profiles of NT1 patients demonstrated specific patterns depending on cataplexy or nap events. Activity data showed significant changes, such as more fragmented and irregular sleep in patients compared to matched controls.
Conclusion. Thermoregulation and circadian rhythm patterns showed alterations in patients with neurodegenerative diseases (AD, PD, and NT1) compared to those of matched healthy controls, therefore identifying potential disease-specific biomarkers. For patients with narcolepsy, distal skin temperature demonstrated a significant reduction within the 5 minutes preceding the onset of cataplexy, suggesting that lower skin temperature increases cataplexy risk.
