An evidence map of actigraphy studies exploring longitudinal associations between rest-activity rhythms and course and outcome of bipolar disorders

Abstract

Background Evidence mapping is a structured approach used to synthesize the state-of-the-art in an emerging field of research when systematic reviews or meta-analyses are deemed inappropriate. We employed this strategy to summarise knowledge regarding longitudinal ecological monitoring of rest-activity rhythms (RAR) and disease modifiers, course of illness, treatment response or outcome in bipolar disorders (BD). Structure We had two key aims: (1) to determine the number and type of actigraphy studies of in BD that explored data regarding: outcome over time (e.g. relapse/recurrence according to polarity, or recovery/remission), treatment response or illness trajectories and (2) to examine the range of actigraphy metrics that can be used to estimate disruptions of RAR and describe which individual circadian rhythm or sleep–wake cycle parameters are most consistently associated with outcome over time in BD. The mapping process incorporated four steps: clarifying the project focus, describing boundaries and ‘coordinates’ for mapping, searching the literature and producing a brief synopsis with summary charts of the key outputs. Twenty-seven independent studies (reported in 29 publications) were eligible for inclusion in the map. Most were small-scale, with the median sample size being 15 per study and median duration of actigraphy being about 7 days (range 1–210). Interestingly, 17 studies comprised wholly or partly of inpatients (63%). The available evidence indicated that a discrete number of RAR metrics are more consistently associated with transition between different phases of BD and/or may be predictive of longitudinal course of illness or treatment response. The metrics that show the most frequent associations represent markers of the amount, timing, or variability of RAR rather than the sleep quality metrics that are frequently targeted in contemporary studies of BD. Conclusions Despite 50 years of research, use of actigraphy to assess RAR in longitudinal studies and examination of these metrics and treatment response, course and outcome of BD is under-investigated. This is in marked contrast to the extensive literature on case–control or cross-sectional studies of actigraphy, especially typical sleep analysis metrics in BD. However, given the encouraging findings on putative RAR markers, we recommend increased study of putative circadian phenotypes of BD.

Neurobiological and behavioral mechanisms of circadian rhythm disruption in bipolar disorder: A critical multi‐disciplinary literature review and agenda for future research from the ISBD task force on chronobiology

“…However, the direction of causality and specificity of these comorbidities with BD illness course are not clear. When considering actigraphy studies in exploring the course of BD over time, a systematic review of 27 studies identified rest/activity metrics including total activity, timing, and variability that were consistently associated with transition between different phases of BD that may be predictive of longitudinal course 251 …”

Chronotypes and circadian rest–activity rhythms in bipolar disorders: a meta‐analysis of self‐ and observer rating scales

“…For instance, disruptions of CRAR have been associated with an earlier age at onset, a more unstable course of BD, suicidality, emotional dysregulation, depressive residual symptoms, worse metabolic health, poor functioning and lower response to lithium. 54,62,[80][81][82][83][84][85][86][87][88] It would be sensible to encourage more widespread longitudinal monitoring of CRAR disturbances in BD, especially as several reviews highlight that they can be effectively targeted by psychoeducational interventions (such as sleep hygiene, regular physical activity, stabilizing sleep-wake cycles) or other so called 'chronotherapeutics'. 89 In the longer term, we hope that clinical practice guidelines offer advice on the monitoring and management of CRAR in BD, as current editions do not give sufficient attention to this issue (e.g.…”

“…The assessment of CRAR in BD can enhance our research understanding of the underlying pathophysiological processes, but also it is important clinically as evidence indicates that CRAR may influence the onset, course and outcome of BD. For instance, disruptions of CRAR have been associated with an earlier age at onset, a more unstable course of BD, suicidality, emotional dysregulation, depressive residual symptoms, worse metabolic health, poor functioning and lower response to lithium 54,62,80‐88 . It would be sensible to encourage more widespread longitudinal monitoring of CRAR disturbances in BD, especially as several reviews highlight that they can be effectively targeted by psychoeducational interventions (such as sleep hygiene, regular physical activity, stabilizing sleep–wake cycles) or other so called ‘chronotherapeutics’ 89 .…”

Can machine learning with data from wearable devices distinguish disease severity levels and generalise across patients? A pilot study in Mania and Depression

“…In fact, wearables collecting highly detailed actigraphy, sleep and cardiovascular information have already been shown to accurately capture rest-activity rhythms, illness activity and episodes in BD [14, 10, 11]. However, their longitudinal potential on treatment response and outcomes remains poorly investigated [38]. Electrodermal activity (EDA) hyporeactivity, denoting autonomic dysfunction, has long been recognized as a strong predictive biomarker for both unipolar and bipolar depression as well as suicidal behaviour [19, 15, 36].…”