title: Bipolar disorder dynamics: affective instabilities, relaxation oscillations and noise.
abstract: Bipolar disorder is a chronic, recurrent mental illness characterized by extreme episodes of depressed and manic mood, interspersed with less severe but highly variable mood fluctuations. Here, we develop a novel mathematical approach for exploring the dynamics of bipolar disorder. We investigate how the dynamics of subjective experience of mood in bipolar disorder can be understood using a relaxation oscillator (RO) framework and test the model against mood time-series fluctuations from a set of individuals with bipolar disorder. We show that variable mood fluctuations in individuals diagnosed with bipolar disorder can be driven by the coupled effects of deterministic dynamics (captured by ROs) and noise. Using a statistical likelihood-based approach, we show that, in general, mood dynamics are described by two independent ROs with differing levels of endogenous variability among individuals. We suggest that this sort of nonlinear approach to bipolar disorder has neurobiological, cognitive and clinical implications for understanding this mental illness through a mechacognitive framework.
authors.affiliation: Department of Zoology, University of Oxford, Oxford OX1 3PS, UK St Peter's College, Oxford OX1 2DL, UK michael.bonsall@zoo.ox.ac.uk.
authors.forename: Michael B
authors.identifier: http://orcid.org/0000-0003-0250-0423
authors.initials: MB
authors.lastname: Bonsall
authors.affiliation: Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford OX1 7JX, UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Geddes
authors.affiliation: Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford OX1 7JX, UK.
authors.forename: Guy M
authors.initials: GM
authors.lastname: Goodwin
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK Department for Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Holmes
mesh_terms: D001683:Biological Clocks; D001714:Bipolar Disorder / Q000503:physiopathology*; D003071:Cognition; D006801:Humans; D008954:Models, Biological
keywords: likelihood; mechacognition; mood dynamics; mood variability