title: Heart rate variability response to mental arithmetic stress in patients with schizophrenia: autonomic response to stress in schizophrenia.
abstract: BACKGROUND
  The vulnerability-stress hypothesis is an established model of schizophrenia symptom formation. We sought to characterise the pattern of the cardiac autonomic response to mental arithmetic stress in patients with stable schizophrenia.
  
  
  METHODS
  We performed heart rate variability (HRV) analysis on recordings obtained before, during, and after a standard test of autonomic function involving mental stress in 25 patients with DSM-IV schizophrenia (S) and 25 healthy individuals (C).
  
  
  RESULTS
  Patients with schizophrenia had a normal response to the mental arithmetic stress test. Relative contributions of low-frequency (LF) HRV and high-frequency (HF) HRV influences on heart rate in patients were similar to controls both at rest (LF 64+/-19% (S) vs. 56+/-16% (C); HF 36+/-19% (S) vs. 44+/-16% (C), t=1.52, p=0.136) and during mental stress, with increased LF (S: 76+/-12%, C: 74+/-11%) and decreased HF (S: 24+/-12%, C: 26+/-11%) in the latter study condition. Whilst healthy persons recovered the resting pattern of HRV immediately after stress termination (LF 60+/-15%, HF 40+/-15%, F=18.5, p<0.001), in patients HRV remained unchanged throughout the observed recovery period, with larger LF (71+/-17%) and lower HF (29+/-17%) compared with baseline (F=7.3, p=0.013).
  
  
  CONCLUSIONS
  Patients with schizophrenia exhibit a normal response to the mental arithmetic stress test as a standard test of autonomic function but in contrast with healthy individuals, they maintain stress-related changes of cardiac autonomic function beyond stimulus cessation.
authors.affiliation: Department of Neurology, Fundación Lucha contra Enfermedades Neurológicas de la Infancia (FLENI), Buenos Aires, Argentina.
authors.forename: Mariana N
authors.initials: MN
authors.lastname: Castro
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Vigo
authors.forename: Hylke
authors.initials: H
authors.lastname: Weidema
authors.forename: Rodolfo D
authors.initials: RD
authors.lastname: Fahrer
authors.forename: Elvina M
authors.initials: EM
authors.lastname: Chu
authors.forename: Delfina
authors.initials: D
authors.lastname: de Achával
authors.forename: Martín
authors.initials: M
authors.lastname: Nogués
authors.forename: Ramón C
authors.initials: RC
authors.lastname: Leiguarda
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cardinali
authors.forename: Salvador M
authors.initials: SM
authors.lastname: Guinjoan
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005583:Fourier Analysis; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011340:Problem Solving / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D012016:Reference Values; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D012815:Signal Processing, Computer-Assisted; D013315:Stress, Psychological / Q000150:complications*