title: Point-process nonlinear autonomic assessment of depressive states in bipolar patients.
abstract: BACKGROUND
  This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems".
  
  
  OBJECTIVE
  The goal of this work is to apply a computational methodology able to characterize mood states in bipolar patients through instantaneous analysis of heartbeat dynamics.
  
  
  METHODS
  A Point-Process-based Nonlinear Autoregressive Integrative (NARI) model is applied to analyze data collected from five bipolar patients (two males and three females, age 42.4 ± 10.5 range 32 -56) undergoing a dedicated affective elicitation protocol using images from the International Affective Picture System (IAPS) and Thematic Apperception Test (TAT). The study was designed within the European project PSYCHE (Personalised monitoring SYstems for Care in mental HEalth).
  
  
  RESULTS
  RESULTS demonstrate that the inclusion of instantaneous higher order spectral (HOS) features estimated from the NARI nonlinear assessment significantly improves the accuracy in successfully recognizing specific mood states such as euthymia and depression with respect to results using only linear indices. In particular, a specificity of 74.44% using the instantaneous linear features set, and 99.56% using also the nonlinear feature set were achieved. Moreover, IAPS emotional elicitation resulted in a more discriminant procedure with respect to the TAT elicitation protocol.
  
  
  CONCLUSIONS
  A significant pattern of instantaneous heartbeat features was found in depressive and euthymic states despite the inter-subject variability. The presented point-process Heart Rate Variability (HRV) nonlinear methodology provides a promising application in the field of mood assessment in bipolar patients.
authors: Gaetano Valenza, Ph.D., Department of Information Engineering, Research Centre "E. Piaggio", Faculty of Engineering, University of Pisa, Via G. Caruso 16, 56122 Pisa, Italy.
authors: G
authors: G
authors: Valenza
authors: L
authors: L
authors: Citi
authors: C
authors: C
authors: Gentili
authors: A
authors: A
authors: Lanatá
authors: E P
authors: EP
authors: Scilingo
authors: R
authors: R
authors: Barbieri
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000503:physiopathology; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000706:statistics & numerical data; D017711:Nonlinear Dynamics; D011581:Psychological Tests / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Bipolar Disorder; Bispectrum; Heart Rate Variability (HRV); High Order Statistics; International Affective Picture System (IAPS); Nonlinear Analysis; Point Process; Thematic Apperception Test (TAT); Wiener-Volterra Series