Abstract
Background: In an earlier study comparing obsessive-compulsive disorder (OCD) patients
to psychiatrically screened normals, we found lowered motor evoked potential (MEP)
threshold to transcranial magnetic stimulation (TMS) and decreased intracortical inhibition
in OCD. We sought to determine whether this pattern was specific to OCD.
Methods: We measured the threshold and amplitude of MEPs to single and paired (subthreshold-suprathreshold;
3, 4, 10, 15 msec intervals) TMS in 46 healthy volunteers (23 women, 23 men) who were
given the NEO-PI-R personality inventory. Nineteen of the men also received cognitive
and motor tests.
Results: The paired-pulse conditioned/unconditioned MEP amplitude ratios correlated
with Neuroticism (N), a stable measure of trait-level anxiety and other negative emotions,
in the whole sample (r = 0.48; p = 0.0006), and in the men (r = 0.63; p = 0.0009). There were no other significant correlations.
Conclusions: This relationship reflects a factor that contributes to both personality
and cortical regulation. It was not statistically significant in women, probably because
of confounding hormonal influences on excitability. Decreased intracortical inhibition
may be related more to trait anxiety and depression, which are high in OCD, than to
OCD itself. However, the MEP threshold (significantly lowered in OCD) was unrelated
to N.
Keywords
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Article info
Publication history
Accepted:
May 21,
2001
Received in revised form:
May 11,
2001
Received:
March 23,
2001
Identification
Copyright
© 2001 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
