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Updated: Apr 12, 2026
Measuring Cardiac Autonomic Nervous System ANS Activity in Toddlers - Resting and Developmental Challenges
Published on: February 25, 2016
Reduction of autonomic regulation in children and adolescents with conversion disorders
Kasia Kozlowska1, Donna M Palmer, Kerri J Brown
1From the Department of Psychological Medicine (Kozlowska, Chudleigh), The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Disciplines of Psychiatry (Kozlowska, Brown, McLean) and of Paediatrics and Child Health (Kozlowska), University of Sydney Medical School, Sydney, New South Wales, Australia; Brain Dynamics Centre (Kozlowska, Palmer), Westmead Millennium Institute for Medical Research and University of Sydney Medical School, Sydney, New South Wales, Australia; Royal Australian College of Physicians (Brown), Sydney, New South Wales, Australia; SWaGS Psychiatry Training Network (McLean), WSLHD, Sydney, New South Wales, Australia; BMRI (McLean) and Department of Psychology (Chudleigh), University of Sydney, Sydney, New South Wales, Australia; Consultation-Liaison Psychiatry (McLean), Royal North Shore Hospital, Sydney, New South Wales, Australia; CSPP (Gevirtz), Alliant International University, San Diego, California; Department of Psychiatry (Scher), Harvard Medical School, Boston, Massachusetts; McLean Hospital (Scher), Belmont, Massachusetts; School of Public Health (Scher), Sydney University Medical School, Sydney, New South Wales, Australia; and Department of Psychiatry and Behavioral Sciences (Williams), Stanford University School of Medicine, Stanford, California.
Objective:
Conversion symptoms--functional neurological disturbances of body function--occur in association with extreme arousal, often in the context of emotional distress. The mechanisms that determine how and why such symptoms occur remain unknown. In this study, we used cardiac measures to assess arousal and cardiac autonomic regulation in children and adolescents who presented with acute conversion symptoms.
Methods:
Heart rate was recorded in 57 children and adolescents (41 girls; 8.5-18 years old) with acute conversion symptoms and 57 age- and sex-matched healthy controls, during a resting condition and then during tasks involving cognitive and emotional activation. Arousal and autonomic regulation were assessed by measures of heart rate and heart rate variability. Psychological measures included attachment and emotional distress.
Results:
Children and adolescents with conversion symptoms displayed higher autonomic arousal than did the controls, both at baseline and during task conditions (higher heart rate: baseline mean [standard deviation] = 82 [9.49] versus 74 [10.79] beats/min, p < .001; lower root mean squared successive differences-heart rate variability: 45.35 [27.97] versus 58.62 [25.69] ms(2), p = .012; and lower high-frequency heart rate variability: 6.50 [1.19] versus 7.01 [0.95] ln[ms(2)] p = .017), and decreased autonomic regulation (attenuation of heart rate increases across tasks). The baseline pattern of increased autonomic arousal was especially pronounced in children with coercive-preoccupied patterns of attachment. Autonomic measures were not correlated with measures of emotional distress.
Conclusions:
High autonomic arousal may be a precondition for generating conversion symptoms. Functional dysregulations of the cardiac, respiratory, and circulatory systems may mediate fainting episodes and nonepileptic seizures, and aberrant patterns of functional connectivity between motor areas and central arousal systems may be responsible for generating motor conversion symptoms.
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