Original Research
Association of QEEG Findings With Clinical Characteristics of
OCD: Evidence of Left Frontotemporal Dysfunction
Ôenel
Tot, MD1,
Aynur Özge, MD2,
Ülkü Çömeleko—lu,
PhD3,
Kemal Yazici, MD4,
Nilgün Bal, MD5
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Objective: Our objectives were 1) to determine hemispheric
asymmetry and regional differences on the EEGs of patients
with obsessive–compulsive disorder (OCD); and 2) to investigate
the effects of sex, treatment response, illness duration,
and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores
on quantitative electroencephalographic (QEEG) measurements.
Method: We recorded EEGs (12-channel) from 22 unmedicated
patients with OCD but no depression and from 20 age- and sex-matched
control subjects. All patients and control subjects underwent
detailed neurological and psychiatric evaluations including
the Hamilton Depression Rating Scale (HDRS) and Y-BOCS.
Results: QEEG revealed higher frequencies of slow-wave
bands and lower frequencies of alpha activity at predominantly
left frontotemporal localization in patients with OCD, compared
with control subjects. Analysis of variance of QEEG parameters
and clinical characteristics showed that sex had a significant
effect on delta and alpha frequencies of frontotemporal areas
during hyperventilation (HV). Increasing total Y-BOCS score
correlated positively with increased frequencies of right
parietal delta activity and decreased frequencies of right
frontotemporal alpha activity during HV. A significantly increased
left frontal slow-wave activity and decreased beta activity
during HV in treatment responders led us to consider that
frontal lobe functions were better in this group of patients.
Illness duration had no important effect on QEEG.
Conclusion: Patients with OCD showed important frontotemporal
dysfunction, predominantly in the left hemisphere. This was
particularly evident in female subjects and in treatment responders.
QEEG may be beneficial in understanding the neurobiological
basis of OCD.
(Can J Psychiatry 2002;47:538–545)
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Clinical Implications
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The finding of left frontotemporal dysfunction
observed in visual EEG in patients with obsessive–
compulsive disorder (OCD) has been confirmed by
quantitative electroencephalographic (QEEG) measurements.
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Left frontotemporal dysfunction was most significant
in female patients with OCD and in treatment responders.
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The severity of left frontotemporal dysfunction
correlated positively with the severity of OCD.
Limitations
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Because specific software was lacking, we performed
QEEG analysis by transferring the data obtained
from the EEG equipment software to a statistical
computer program, and this method may have caused
some errors.
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A second QEEG analysis was not performed at the
end of the treatment period.
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A single activation method (hyperventilation) was
used in EEG.
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The number of male patients was relatively low.
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Key Words: obsessive-compulsive disorder,
electroencephalogram, EEG, quantitative analysis, hemispheric
asymmetry, left hemisphere, frontotemporal dysfunction
Résumé
: Association des résultats des mesures EEGQ avec les
caractéristiques cliniques du trouble obsessionnel-compulsif
: preuve de la dysfonction frontotemporale gauche
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Obsessive–compulsive disorder (OCD) is characterized by recurrent
and disturbing thoughts (obsessions) or repetitive and stereotyped
behaviours (compulsions), or both, that the sufferer feels driven
to perform but recognizes as irrational or excessive (1,2). Over
the past decade, there has been increasing interest in the neurobiological
basis of OCD. Neuroimaging and positron emission tomography (PET)
studies indicate an increased prevalence of neurological soft signs
and increased metabolism in the frontal cortex, basal ganglia, and
cingulate gyrus (3–9).
There are relatively few studies investigating the EEG manifestations
of the obsessional syndrome. In the first such study, Pacella and
others found that 64% of 31 patients had definite EEG abnormalities,
principally in the slow-wave frequencies (10). This was confirmed
by Rockwell and Simons, who obtained EEG abnormalities in the same
frequency bands in 54% of 24 patients (11). Epstein and Bailine
described the appearance of temporal spikes during stage I and the
REM phase of sleep in 3 patients with obsessional symptoms and abnormal
waking EEG, but without epilepsy (12).
Flor-Henry and others reported relatively decreased variability
in the left temporal region (3). Insel and others reported that,
in subjects found to have abnormal EEGs, the abnormality was “nonspecific
theta activity” (13). In reviewing EEG data obtained from patients
with OCD, Jenike and Brotman concluded that EEG disturbances, when
present, were predominantly in the temporal and frontotemporal regions
(14).
In a detailed quantitative electroencephalographic (QEEG) study,
Khanna found decreased power in the nondominant frontotemporal and
posterior temporal regions (15). In an important study using QEEG
and brain mapping, Perros and others found significantly increased
relative power in the theta-2 band in the left temporal and central
regions and significantly reduced variability in frontal and temporal
regions (16).
Prichep and others reported the existence of 2 subtypes of OCD
patients within a clinically homogeneous group of patients who met
DSM-III-R criteria for OCD. Their QEEG results suggested that Cluster
1 (treatment nonresponders) was characterized by excess relative
power in theta, especially in the frontal and frontotemporal regions,
and Cluster 2 (treatment responders) was characterized by increased
relative power in alpha (9).
Drake and others compared EEG spectral measures in patients with
OCD and in healthy control subjects and reported that modal alpha
frequency (MAF) and maximal alpha frequency (MxAF) were reduced
in the frontal regions in patients, compared with control subjects
(17). Most of these observations support the hypothesis that obsessions
and compulsions have a physiologic basis and frontal lobe disturbance
in their pathophysiology. However, studies conducted so far have
described EEG changes obtained from restricted region recordings.
The association of EEG findings with the clinical characteristics
of OCD and with patients’ sex has not been clarified.
This study investigates EEG changes at resting state (RS) and during
hyperventilation (HV) in unmedicated OCD patients without depression
and in healthy control subjects. It also investigates the possible
association of clinical characteristics of OCD and QEEG findings.
Method
Subjects
The patients and the control subjects were matched for age and
sex. Table 1 gives
their demographic characteristics. We selected 22 right-handed OCD
patients as the study group and 20 right-handed healthy subjects
as the control group. Patients were consecutively selected from
among those applying to the psychiatric outpatient clinic of Mersin
University Faculty of Medicine. Twelve patients had never taken
treatment for OCD. Ten patients had previous treatment periods but
had not taken psychotropic drugs for at least 2 weeks prior to the
study, either from noncompliance or because of adverse effects.
None of the control subjects had a history of any psychiatric disorder,
and none had ever taken drugs affecting the central nervous system
(CNS). Inclusion criteria for the study were as follows: 1) a strict
DSM-IV diagnosis of OCD, 2) the presence of symptoms for at least
1 year, 3) being free of psychotropic drugs for at least 2 weeks
prior to the study, 4) being neurologically intact (that is, without
epilepsy, stroke, head injury, dementia, or sleep disorder), 5)
being free of concomitant severe or chronic medical illnesses (for
example, hepatic failure or chronic renal failure) or comorbid psychiatric
disorders (for example, other anxiety disorders, depression, schizophrenia,
or substance abuse), and 6) having no history of psychosurgery or
any other neurosurgical procedure. All patients received treatment
for OCD. Depressive symptoms on the Hamilton Depression Rating Scale
(HDRS) were absent or mild (that is, scores were below 15) (18).
Validity and reliability of the Turkish version of the HDRS has
been tested by Akdemir and others (19). Patients reported a wide
range of obsessions and compulsions. Most often, these included
hand-washing, checking, and hoarding compulsions and contamination,
aggressive, somatic, and religious obsessions, as well as pathological
doubt. Eight patients showed obsessional thoughts without significant
compulsions. We administered the Yale-Brown Obsessive Compulsive
Scale (Y-BOCS) to assess the severity of obsessive–compulsive
symptoms (20,21). Validity and reliability of the Turkish version
of Y-BOCS has been tested by Tek and others (22).
After clinical evaluation, patients were started on pharmacotherapy
(11 patients on fluvoxamine [dosage range, 100 to 300 mg daily],
4 on fluoxetine [dosage range, 20 to 80 mg daily], and 5 on sertraline
[dosage range, 100 to 200 mg daily]). Treatment drugs were determined
on the basis of previous treatment and adverse effects. Dosages
were adjusted according to each patient’s clinical condition
and adverse-effect status. At the end of month 3, we evaluated treatment
response, using the Clinical Global Impression Scale (CGI) (23).
Responders were defined as very much improved or much improved,
and nonresponders as those who showed minimal or no change on CGI;
13 patients were responders and 7 patients were nonresponders. Two
patients discontinued drug therapy and were excluded from the treatment-response
analysis.
All subjects gave informed consent after a full explanation of
the study and the EEG testing procedure.
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