Abstract
BackgroundA defining characteristic of Major Depressive Disorder (MDD) is its episodic course, which might indicate that MDD is a nonlinear dynamic phenomenon with two discrete states. We investigated this hypothesis using the symptom time series of individual patients.MethodsIn 178 primary care patients with MDD, the presence of the nine DSM-IV symptoms of depression was recorded weekly for two years. For each patient, the time-series plots as well as the frequency distributions of the symptoms over 104 weeks were inspected. Furthermore, two indicators of bimodality were obtained: the bimodality coefficient (BC) and the fit of a 1- and a 2-state Hidden Markov Model (HMM).ResultsIn 66 % of the sample, high bimodality coefficients (BC > .55) were found. These corresponded to relatively sudden jumps in the symptom curves and to highly skewed or bimodal frequency distributions. The results of the HMM analyses classified 90 % of the symptom distributions as bimodal.ConclusionsA two-state pattern can be used to describe the course of depression symptoms in many patients. The BC seems useful in differentiating between subgroups of MDD patients based on their life course data.
Highlights
A defining characteristic of Major Depressive Disorder (MDD) is its episodic course, which might indicate that MDD is a nonlinear dynamic phenomenon with two discrete states
We explored a longitudinal dataset for evidence of two discrete states, symptom-free versus depressed, in patients with MDD
Out of the 397 patients, 78 refused to participate and 52 met the exclusion criteria, resulting in a sample of 267 patients (67.3 %). These patients were randomly allocated to four treatment arms: (1) care as usual (CAU) following national general practice guidelines, (2) CAU plus psycho-education program (PEP), (3) CAU + PEP + cognitive behavioural therapy, and (4) CAU + PEP + psychiatric consultation
Summary
A defining characteristic of Major Depressive Disorder (MDD) is its episodic course, which might indicate that MDD is a nonlinear dynamic phenomenon with two discrete states. We investigated this hypothesis using the symptom time series of individual patients. Depression might be modelled as a nonlinear dynamic system that is attracted to two different states of behaviour and that at times moves from one state to the other This hypothesis has already been proposed by several authors [5,6,7,8,9], but has not yet been systematically investigated empirically. In one study [9], critical slowing down as an indicator of nearby tipping points predicted mood shifts in depressed patients
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
