J Psychiatry Neurosci 2010; 34(4): 314-322
Mirte J. Bakker, MSc; Marina A.J. Tijssen, MD, PhD; Johan N. van der Meer, MSc; Johannes H.T.M. Koelman, MD, PhD; Frits Boer, MD, PhD
Bakker, Tijssen, van der Meer, Koelman — Department of Neurology and Clinical Neurophysiology; Bakker, Boer —
Department of Child and Adolescent Psychiatry, Academic Medical Centre, University of Amsterdam, The Netherlands
Background: Young patients with anxiety disorders are thought to have a hypersensitive fear system, including alterations of the early sensorimotor processing of threatening information. However, there is equivocal support in auditory blink response studies for an enlarged auditory startle reflex (ASR) in such patients. We sought to investigate the ASR measured over multiple muscles (whole-body) in children and adolescents with anxiety disorders.
Methods: Between August and December 2006, we assessed ASRs (elicited by 8 consecutive tones of 104 dB, interstimulus interval of about 2 min) in 25 patients and 25 matched controls using a case–control design and in 9 nonaffected siblings. We recorded the electromyographic activity of 6 muscles and the sympathetic skin response. We investigated response occurrence (probability %) and response magnitude (area under the curve in μV × ms) of the combined response of 6 muscles and of the single blink response.
Results: In patients (17 girls, mean age 12 years; 13 social phobia, 9 generalized anxiety, 3 other), the combined response probability (p = 0.027) of all muscles, the combined area under the curve of all muscles (p = 0.011) and the sympathetic skin response (p = 0.006) were enlarged compared with matched controls. The response probability (p = 0.48) and area under the curve (p = 0.07) of the blink response were normal in patients compared with controls. The ASR pattern was normal with normal latencies in patients compared with controls. In nonaffected siblings, the sympathetic skin response (p = 0.038), but not the combined response probability of all muscles (p = 0.15), was enlarged compared with controls.
Limitations: Limitations are the sample size and restricted comparison to the psychophysiological ASR paradigm.
Conclusions: The results point toward a hypersensitive central nervous system (fear system), including early sensorimotor processing alterations and autonomic hyperreactivity. The multiple muscle (wholebody) ASR is suggested to be a better tool to detect ASR abnormalities in patients with anxiety disorders than the blink response alone. Abnormalities in ASR serve as a candidate endophenotype of anxiety disorders.
The study was conducted at The Brain Dynamics Centre, Westmead Hospital and University of Sydney, NSW, 2006, Australia.
Submitted Jul. 31, 2008; Revised Oct. 8, 2008, Jan. 6, 2009; Accepted Jan. 7, 2009
Competing interests: None declared for Drs. Bakker, van der Meer, Koelman and Boer. Dr. Tijssen reports having received travel assistance from Boehringer Ingelheim.
Contributors: Drs. Bakker, Tijssen, Koelman and Boer designed the study. Dr. Bakker acquired the data and wrote the article. All authors analyzed the data, reviewed the article and approved its publication.
Correspondence to: Dr. M. Tijssen-de Koning, Department of Neurology, Academic Medical Centre, University of Amsterdam, PO BOX 22660, 1100 DD Amsterdam, The Netherlands; firstname.lastname@example.org