title: [To err is human? Interests of chaotic models to study adult psychiatric disorders and developmental disorders].
abstract: BACKGROUND
  Many clinical and biological parameters have nonlinear chaotic fluctuations. These variations result in unexpected pseudo-random transitions. In these models, few risk factors can lead to unexpected phenomena if oscillations and self-reinforcement patterns occur. Complex rhythms could ease the ability of a physiological system to adapt and react quickly to a constantly changing environment.
  
  
  OBJECTIVE
  It has been proposed that several psychiatric disorders and developmental disorders are characterized by a loss of complex rhythm in favor of a more organized pattern. We examine evidence to support these assumptions in literatures.
  
  
  METHODS
  We performed a literature review of the main computerized databases (Medline, PubMed) and manual searches of the literature concerning non dynamic rhythms in time series analysis, in adults with psychiatric disorder and children with developmental disorder. These results were interpreted through a developmental approach that highlights the role of the learning process in the emergence of abilities.
  
  
  RESULTS
  Analysis of clinical scores and electroencephalographic data have found that subjects with bipolar disorder or schizophrenia, tested over a time series, have lower chaotic rhythms compared with healthy subjects. Growing children share several properties of a complex system: the interdependence of developmental axes (motor, emotional, language, social skills), multiple hierarchical levels (i.e. genetic, biological, environmental, and cultural), the two-way transactions between the child and his environment, and the sensitivity to initial conditions. This could explain the difficulty to predict the emergence of abilities or the long-term prognosis of impairment in children. This limitation is not only due to errors in the explanatory model or the lack of explanatory variable. It is also caused by instability, which is a core characteristic of a chaotic system.
  
  
  CONCLUSIONS
  The study of chaotic rhythms in time-series clinical and nonclinical data (e.g. EEG, functional neuroimaging) could improve the prediction of an acute event, such as relapse of mood disorder. Moreover, the complex rhythms in children may play a major part in synchronicity during interactions with a caregiver, held as essential for later development of self-regulation skills, such as emotional stability.
authors.affiliation: Service de psychiatrie de l'enfant et de l'adolescent, université Pierre-et-Marie-Curie, hôpital Pitié-Salpêtrière, AP-HP, 47-83, boulevard de l'Hôpital, 75013 Paris, France. Electronic address: xavierbenarous@gmail.com.
authors.forename: X
authors.initials: X
authors.lastname: Benarous
authors.affiliation: Service de psychiatrie de l'enfant et de l'adolescent, université Pierre-et-Marie-Curie, hôpital Pitié-Salpêtrière, AP-HP, 47-83, boulevard de l'Hôpital, 75013 Paris, France; CNRS UMR 7222, institut des systèmes intelligents et robotiques, université Pierre-et-Marie-Curie, 4, place Jussieu, 75005 Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Cohen
mesh_terms: D000328:Adult; D002648:Child; D002658:Developmental Disabilities / Q000523:psychology*; D006801:Humans; D001523:Mental Disorders / Q000523:psychology*; D008960:Models, Psychological; D017711:Nonlinear Dynamics
keywords: Chaos theory; Developmental disorder; Developmental psychopathology; Nonlinear dynamic; Psychiatric disorder; Psychopathologie développementale; Système dynamique non linéaire; Théorie du chaos; Trouble du développement; Trouble psychiatrique