title: Altered heart rate dynamics associated with antipsychotic-induced subjective restlessness in patients with schizophrenia.
abstract: BACKGROUND
  Antipsychotic-induced subjective inner restlessness is one of the common and distressing adverse effects associated with antipsychotics; however, its underlying neurobiological basis is not well understood. We examined the relationship between antipsychotic-induced subjective inner restlessness and autonomic neurocardiac function.
  
  
  METHODS
  Twenty-two schizophrenia patients with antipsychotic-induced subjective restlessness, 28 schizophrenia patients without antipsychotic-induced subjective restlessness, and 28 matched healthy control subjects were evaluated. Assessments of the linear and nonlinear complexity measures of heart rate dynamics were performed. Multivariate analysis of variance and correlation analysis were conducted.
  
  
  RESULTS
  The mean interbeat (RR) interval value was significantly higher in control subjects than in patients with and without antipsychotic-induced subjective restlessness (P < 0.05). The low frequency/high frequency ratio was significantly higher in patients with antipsychotic-induced subjective restlessness than in control subjects and in patients without antipsychotic-induced subjective restlessness (P < 0.05), while the approximate entropy value was significantly lower in patients with antipsychotic-induced subjective restlessness than in control subjects and in patients without antipsychotic-induced subjective restlessness (P < 0.05). Correlation analyses controlling for psychotic symptom severity showed that the degree of antipsychotic-induced restlessness had a significant negative correlation with the value of approximate entropy (P < 0.05).
  
  
  CONCLUSIONS
  The results indicate that antipsychotic-induced subjective restlessness is associated with altered heart rate dynamics parameters, particularly the nonlinear complexity measure, suggesting that it might adversely affect autonomic neurocardiac integrity. Further prospective research is necessary to elucidate the precise interrelationships and causality.
authors.affiliation: Department of Psychiatry, Gil Medical center, Incheon, South Korea ; Graduate school of Medicine, Gachon University, Incheon, South Korea.
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Jun-Hyung
authors.initials: JH
authors.lastname: Ann
authors.forename: Jinyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Mee-Hee
authors.initials: MH
authors.lastname: Kim
authors.forename: Ah-Young
authors.initials: AY
authors.lastname: Han
keywords: antipsychotics; heart rate dynamics; subjective restlessness