Heart rate variability response to mental arithmetic stress in patients with schizophrenia: autonomic response to stress in schizophrenia.
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.
Castro
Mariana N
MN
Department of Neurology, Fundación Lucha contra Enfermedades Neurológicas de la Infancia (FLENI), Buenos Aires, Argentina.
Vigo
Daniel E
DE
Weidema
Hylke
H
Fahrer
Rodolfo D
RD
Chu
Elvina M
EM
de Achával
Delfina
D
Nogués
Martín
M
Leiguarda
Ramón C
RC
Cardinali
Daniel P
DP
Guinjoan
Salvador M
SM
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*