title: Correlates of depression in bipolar disorder.
abstract: We analyse time series from 100 patients with bipolar disorder for correlates of depression symptoms. As the sampling interval is non-uniform, we quantify the extent of missing and irregular data using new measures of compliance and continuity. We find that uniformity of response is negatively correlated with the standard deviation of sleep ratings (ρ = -0.26, p = 0.01). To investigate the correlation structure of the time series themselves, we apply the Edelson-Krolik method for correlation estimation. We examine the correlation between depression symptoms for a subset of patients and find that self-reported measures of sleep and appetite/weight show a lower average correlation than other symptoms. Using surrogate time series as a reference dataset, we find no evidence that depression is correlated between patients, though we note a possible loss of information from sparse sampling.
authors.affiliation: Oxford Centre for Industrial and Applied Mathematics (OCIAM), Mathematical Institute, University of Oxford, , Oxford, UK, Smith School of Enterprise and the Environment, University of Oxford, , Oxford, UK, Department of Psychiatry, University of Oxford, , Oxford, UK, MIT Media Lab, Aston University, , Birmingham, UK.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Moore
authors.forename: Max A
authors.initials: MA
authors.lastname: Little
authors.forename: Patrick E
authors.initials: PE
authors.lastname: McSharry
authors.forename: Guy M
authors.initials: GM
authors.lastname: Goodwin
authors.forename: John R
authors.initials: JR
authors.lastname: Geddes
mesh_terms: D000339:Affect / Q000502:physiology*; D001066:Appetite / Q000502:physiology*; D001714:Bipolar Disorder / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D006801:Humans; D008954:Models, Biological; D012621:Seasons; D012890:Sleep / Q000502:physiology*; D013997:Time Factors
keywords: bipolar disorder; mood variability; psychiatry; public healthcare; time-series analysis