Complexity and nonlinear biomarkers in emotional disorders: A meta-analytic study.
This meta-analysis aimed at gathering and summarising the findings on nonlinear biomarkers in the field of emotional disorders under the hypothesis that diseased systems show lowered complexity and hence less flexibility to adjust daily contexts. Scientific manuscripts from 1970 to 2014 were reviewed, 58 articles were analysed, and independent meta-analyses on anxiety disorders, bipolar disorders, and depressive disorders were conducted. Results revealed that anxious patients exhibited lower complexity than controls (p<0.05) despite panic patients showed more irregular respiratory activity. Inconclusive results were found for bipolar patients but pointed to higher randomness when suffering manic episodes. Finally, depressed patients showed a loss of complexity in the cardiac system and a loss of orderliness (despite a higher complexity) in brain and stress-related hormonal systems. As a conclusion, our findings highlight that either a loss of complexity or a loss of ordered complexity characterise the physiological systems of patients with emotional disorders. Several considerations for complexity, its related measurements, and suggestions for further research are discussed.
Research Institute of Health Sciences, University of the Balearic Islands, Spain. Electronic address: a.delatorre@uib.es.
Alejandro
A
de la Torre-Luque
Research Institute of Health Sciences, University of the Balearic Islands, Spain.
Xavier
X
Bornas
Research Institute of Health Sciences, University of the Balearic Islands, Spain.
Maria
M
Balle
Research Institute of Health Sciences, University of the Balearic Islands, Spain.
Aina
A
Fiol-Veny
D001007:Anxiety; D001008:Anxiety Disorders; D015415:Biomarkers; D001714:Bipolar Disorder; D006801:Humans; D019964:Mood Disorders
D015415:Biomarkers
Anxiety disorders; Bipolar disorders; Complexity; Depression; Meta-analysis; Nonlinear dynamical systems theory