O019 Understanding sleep-wake disturbances in dementia with Lewy bodies using parametric and non-parametric measures in wrist actigraphy

Abstract Introduction Sleep-wake disturbances are a commonly reported non-motor symptom in dementia with Lewy bodies patients (DLB). Wrist actigraphy offers a low-burden, cost-effective option to measure sleep disturbances and has demonstrated alterations in rest-activity patterns in other synucleinopathies. This study reports both parametric and non-parametric actigraphy variables in DLB and investigates their associations with cognitive, behavioural, and quality of life measures. Methods Eleven participants with DLB (10:1, M:F) and 7 age-matched healthy controls (5:2, M:F) completed a battery of neuropsychological, cognitive and motor assessments and were given an actigraphy device for 2 weeks. Mann-Whitney U tests were used to compare groups and Spearman’s correlation was used to assess the relationship between actigraphy and cognitive, behavioural and quality of life measures. Results DLB patients reported lower cognitive (p=0.002), motor function (p<0.001) and non-motor function scores (p=0.001), along with increased depression (p=0.014). There were no significant differences between groups for total sleep time or percentage of time awake. However, compared to controls, DLB patients reported higher interdaily variability (transitions between rest and activity) (p=0.015) and lower relative amplitude (the difference between the leave active 5-hour and most active 10-hour patterns in an average 24-hour period) (p=0.011). Furthermore, interdaily stability (the relationship between rest-activity rhythm and the zeitgeber) was positively correlated with depression, hallucinations, and cognitive fluctuations. Discussion Wrist actigraphy and its non-parametric measures may serve as a valuable tool for investigating sleep-wake disturbances in patients with DLB and help better understand the pathophysiological role of rest-activity and circadian rhythm disruption in this condition.