Is disturbed intracortical excitability a stable trait of chronic insomnia? A study using transcranial magnetic stimulation before and after multimodal sleep therapy.

Ysbrand D. van der Werf, Ellemarije Altena, Karin D. van Dijk, Rob L.M. Strijers, Wim De Rijke, Cornelis J. Stam, Eus J.W. van Someren
Biological Psychiatry. 2010-11-01; 68(10): 950-955
DOI: 10.1016/j.biopsych.2010.06.028

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1. Biol Psychiatry. 2010 Nov 15;68(10):950-5. doi: 10.1016/j.biopsych.2010.06.028.
Epub 2010 Aug 21.

Is disturbed intracortical excitability a stable trait of chronic insomnia? A
study using transcranial magnetic stimulation before and after multimodal sleep
therapy.

van der Werf YD(1), Altena E, van Dijk KD, Strijers RL, De Rijke W, Stam CJ, van
Someren EJ.

Author information:
(1)Department of Sleep and Cognition, Netherlands Institute for Neuroscience,
Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The
Netherlands.

BACKGROUND: Chronic insomnia is a poorly understood disorder. Risk factors for
developing chronic insomnia are largely unknown, yet disturbances in brain
indexes of arousal seem to accompany the disorder. We here investigate whether
insomnia patients and control participants differ with respect to brain responses
to direct stimulation, i.e., cortical excitability. Transcranial magnetic
stimulation (TMS) offers a method to directly investigate the excitability level
of the human cerebral cortex in psychiatric and neurological disease.
METHODS: We investigated cortical excitability in 16 insomnia patients and 14
carefully matched control participants using absolute and relative amplitudes of
motor evoked potentials in response to single- and paired-pulse stimulation using
TMS.
RESULTS: Nonmedicated insomnia patients showed, first, an exaggerated absolute
response to both suprathreshold single- and paired-pulse stimulation compared
with control participants and second, a reduced relative response to paired-pulse
stimulation at long interpulse intervals (i.e., a reduced intracortical
facilitation). The abnormal excitability persisted despite sleep therapy that
effectively improved sleep quality as well as behavioral and neuroimaging indexes
of brain function.
CONCLUSIONS: The results suggest that a subtly disturbed intracortical
excitability characterizes patients with chronic insomnia: a relatively reduced
intracortical facilitation in the context of a globally increased absolute
excitability. The findings do not resemble TMS findings after sleep deprivation
or in sleep apnea and thus seem specific to insomnia. They may offer diagnostic
value and implications for assessment of risk to develop this common and
disabling disorder.

Copyright © 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All
rights reserved.

DOI: 10.1016/j.biopsych.2010.06.028
PMID: 20728874 [Indexed for MEDLINE]


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