Institute of Psychiatry and Maudsley Hospital, London
Healthcare Technology Systems, Madison, WI, USA
Harvard University Department of Psychiatry, Cambridge, MA, USA
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Correspondence: Professor I. M. Marks, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AZ
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ABSTRACT |
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Aims To develop a way to assess mental imagery in OCD during functional magnetic resonance imaging (fMRI).
Method A small randomised study, controlled for type and order of mental imagery and for treatment condition (exposure therapy guided by a computer or by a therapist, or relaxation guided by audio-tape). Before and after treatment, during fMRI scanning, patients imagined previously-rehearsed scenarios that evoked an urge to ritualise or non-OCD anxiety or a neutral state, and rated their discomfort during imagery.
Results The method evoked greater discomfort during OCD imagery and anxiety (non-OCD) imagery than during neutral imagery. Discomfort was reduced by cancelling imagery. Discomfort during OCD imagery (but not during anxiety non-OCD imagery) fell after exposure therapy but not after relaxation.
Conclusions Results showed differences between OCD and non-OCD images and their change after successful treatment, and confirmed clinical suggestions that cancelling images reduced OCD discomfort. The method's success paves the way for further studies of mental imagery in OCD: for instance, during fMRI.
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INTRODUCTION |
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METHOD |
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Mental imagery during fMRI scanning
Pre-scanning rehearsal outside the scanner
Before the first fMRI session, the researcher asked the patient to choose
and mentally rehearse for a few minutes each of three tasks to be performed
during scanning. Each task involved imagining (I), an image designed to induce
one of three states: (i) urge to ritualise; (ii) non-OCD anxiety, (iii)
neutral state; followed by (II), a second image designed to cancel the first
one. The scenarios imagined were specific to each patient, and the researcher
wrote on a card the detailed content of each of the six images ((I) and (II)
for each of the three tasks) which patients then rehearsed for a few minutes
until they could generate each image reliably.
For image (I) (300 s) of each task, patients had to imagine a scene they said would:
For image (II) (300 s) of each task patients had to switch to another scene that would:
Protocol inside the fMRI scanner
After preliminary adjustment and when patients felt comfortable (10-15 min)
they had three 600 s fMRI scanning runs, one during each of the three tasks
(ritual-evoking, anxiety-evoking, or pleasant). The order of the three tasks
was allocated randomly across patients. Patients did not know which order of
tasks they would be asked to do until the moment the researcher asked them to
start each task.
During scanning patients were invited to lie still and to generate and hold the image for the given task when instructed. Immediately before the task the researcher read from the prepared card into the scanner microphone the image the patient was to imagine. When the subject said that he or she had generated the image clearly and vividly, fMRI scanning began and continued for 600 s. After 300 s (end of image (a)) the researcher read to the patient the cancelling image (b) to start and hold for 300 s.
During each 600 s period of imagery and scan, the researcher asked subjects every 30 s to rate their anxiety/discomfort rating on a 0-8 scale (0=no anxiety; 8=panic) by saying the relevant number out loud. This yielded a total of 20 self-ratings per 600 s task. Between the three tasks, patients rested in the scanner for 1-2 min.
The treatments
The pilot randomised controlled trial used the protocol of a multi-centre
randomised controlled test of BTSTEPS in North America done in parallel
without fMRI scans (further details available from the author upon request),
and was approved by the local Ethical Committee. Fifteen patients were
randomly allocated (by computer-generated random numbers, with minimalisation
regarding numbers per cell) to have one of three treatments: (a) ERP guided by
BTSTEPS (group B, n=5); (b) ERP guided face-to-face by a therapist
(group T, n=4); and (c) control relaxation treatment (group R,
n=6) guided by an audio-tape plus manual given by a therapist. After
treatment, 100 patients in group R who had not improved crossed over to have
the group B treatment, and after that had a third fMRI scan.
The three treatment conditions
All three treatments were given over 10 weeks, and patients were asked to
keep daily diaries of ERP, or of relaxation, homework done. Group T patients
had 10 weekly 60-min sessions with a therapist. Patients in groups B and R,
after being told after initial assessment what to do, had no further contact
with a therapist; however, they saw the study coordinator 2 weeks before
starting (for screening for suitability for the trial and to give written
consent to participate), at baseline (randomisation to start of treatment),
and at weeks 2, 6 and 10 (end of treatment) for rating of outcome and checking
of mood, and they could contact the coordinator by telephone if there were
problems.
Patients in group B were given a BTSTEPS workbook and an identification number and chose a personal four-digit password number for confidentiality. They could access the BTSTEPS computer tollfree 24 hours a day, 7 days a week. On the phone, patients performed repeated computer interviews for self-assessment and ERP self-treatment, driving their interviews mainly by key-presses on their telephone keypad. Users did each telephone interview after completing the relevant section in their workbook.
For group T, ERP was guided face-to-face by a live trained human therapist. Patients were taught prolonged daily self-exposure to situations that evoked rituals and obsessions and to resist ensuing urges to ritualise. One therapist left on maternity leave half-way through treatment, after which another continued the treatment.
Patients in group R were asked to do daily self-administered progressive relaxation exercises along the careful lines of Jacobsen (1938), and were given a structured relaxation audio-tape and manual to help them.
All patients were asked to do ERP or relaxation homework exercises for an hour a day and to record these exercises in daily ERP or relaxation homework diaries.
Patient inclusion criteria
Minimum age 14; having had OCD (DSM-IV criteria;
American Psychiatric Association,
1994) for over 2 years; total score on the Yale-Brown Obsessive
Compulsive Scale (YBOCS; Goodman et
al, 1989) over 15, including over 7 on
compulsions or over 9 on that sub-scale if the YBOCS total was
9-14; if on serotonergic antidepressants (clomipramine, paroxetine,
sertraline, fluoxetine or fluvoxamine), they must have been on a stable dose
for over 3 months before enrolment; must have given written informed
consent.
Must have none of the following: other psychotropic medication in the past 3 months; electroconvulsive therapy in the past 6 months; suicidal plans; score greater than 15 on a depression scale based on the 17-item Hamilton Rating Scale for Depression (HRSD); bipolar disorder; history of major tics or Tourette's syndrome; schizophrenia; unstable medical condition; alcohol/substance abuse in the 6 months before enrolment; organic brain syndrome; developmental disorder or disability impairing participation or understanding of ERP or relaxation; schizotypal personality disorder; psychosurgery; need for in-patient care.
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RESULTS |
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Description of patients
The 15 patients (nine men, six women) came from a waiting list for
out-patient behaviour therapy. All were native English speakers living in
greater London. Their mean age was 32 years (s.d.=7). Twelve were employed or
were students. The mean of the OCD duration was 18 years (s.d.=10); their main
problems were checking (six), washing (three), mental rituals (four), and a
mixture of these in two patients. Seven were on a stable dose of clomipramine
or an SSRI. The three treatment groups were similar in all these respects and
as regards chronic moderate-to-severe OCD and work/social disability. At week
0, self-rated mean scores were: YBOCS 28.2 (s.d.=5.3; actual range 6-40,
possible range 0-40); work/social adjustment (WSA;
Marks, 1986) total 21
(s.d.=8.2; possible range 0-40), Hamilton depression (six-item Bech version;
Bech et al, 1981) 9.4
(s.d.=7; possible range 0-40) (higher values=more severe OCD). One subject did
not complete the protocol because of claustrophobia in the scanner. Another
persisted, but was overwhelmed by panic throughout. The analysis below
therefore refers mostly to the 13 patients who completed the protocol.
Pre-treatment responses to task images
The three tasks were to imagine a ritual-evoking (OCD), anxiety-(non-OCD)
evoking or neutral scene for 300 s (image (I)) and then to imagine a scene to
cancel it for 300 s (image (II), see above). Patients rated discomfort every
30 s; their 10 discomfort ratings per 300 s image were pooled for that
image.
Image (I) evoked substantial discomfort with both OCD and anxiety (non-OCD) scenes, but not with neutral scenes. On a scale of 0-8 (8=most discomfort possible), mean discomfort evoked by the OCD image was 5.25 (s.d.=1.6, range 2.3-7.9), by the anxious (non-OCD) image it was 4.85 (s.d.=1.68, range 2.5-7.5) and by the neutral scene was 1.55 (s.d.=1.3, range 0-4.5) (Fig. 1: OCD I, ANX I and NEU I). During both the OCD image and the anxiety (non-OCD) image, discomfort was significantly higher than during the neutral image (respectively t=6.07, t=5.12; P < 0.0001, P < 0.0001).
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The cancelling image (II) successfully reduced discomfort to both OCD and anxiety (non-OCD) scenes and there was little discomfort during the neutral scene (Fig. 1: OCD II, Anx II and NEU II). Mean discomfort scores during the OCD task changed from 5.25 (s.d.=1.61) for image (I) to 3.05 (s.d.=1.37) for its cancelling image (II) (t=5.85; P=0.001) (Fig. 2). Mean discomfort scores during the anxiety (non-OCD) task changed from 4.85 (s.d.=1.68) for image (I) to 2.09 (s.d.=0.89) for its cancelling image (II) (t=6.12; P=0.001). Though the cancelling image (II) significantly reduced discomfort from image (I), that reduction was not right down to the level found during neutral image (II).
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Change from before to after treatment in response to image (I)
During OCD image (I), discomfort fell significantly from before to after
the treatment in the two ERP groups B and T pooled, from 5.1 (s.d.=1.08) to
3.4 (s.d.=1.9) (t=2.68, P=0.03)
(Fig. 2: OCDpre and OCDpost).
For the two ERP groups separated, the fall in group B was from a mean of 4.9
(s.d.=1) to 2.8 (s.d.=1.4) (t=2.5, P=0.07), and less in
group T, from 5.5 (s.d.=0.7) to 4.4 (s.d.=2.6) (t=9, P=0.5).
Discomfort during OCD image (I) remained unchanged before and after treatment
in group R: 5.7 (s.d.=3.0) to 5.8 (s.d.=2.7).
During anxiety (non-OCD) image (I), discomfort showed almost no change from
before to after treatment in groups B (4.04.2), T (5.0
5.3) or R
(5.2
5.4).
During the neutral image (I) too, there was almost no change from before to
after treatment: group B 1.20.8, group T 2.1
2.3, group R
(0.9
0.6).
Change from before to after treatment in response to image (II)
Before treatment, the cancelling image (II) had reduced discomfort during
OCD and the non-OCD anxiety image (I), but some discomfort had remained during
image (II). From before to after treatment, during OCD image (II) discomfort
fell significantly in the two ERP groups B and T pooled, from a mean of 3.5
(s.d.=1.0) to 1.8 (s.d.=1.8) (t=1.9, P=0.02)
(Fig. 3: OCDpre and OCDpost).
For the two groups separated, the fall in group B was from a mean of 3.5
(s.d.=1.2) to 1.6 (s.d.=1.3) (t=2.19, P=0.09), and less in
group T from 3.5 (s.d.=1.0) to 2.0 (s.d.=1.9) (t=0.17,
P=0.23). Discomfort during OCD image (II) rose marginally though
significantly from before to after treatment in group R, from 2.7 (s.d.=2.1)
to 3.1 (s.d.=2.0) (P=0.02).
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During the anxiety (non-OCD) image (II), discomfort did not change
significantly from before to after treatment in the two ERP groups B and T
pooled (2.42.08, t=1.44, P=0.19) or separated (B:
2.14
1.5, t=1.8, P=0.14, T: 2.9
3.0,
t=1.0, P=0.4) or in group R (1.9
2.2, t=0.87,
P=0.5).
During the neutral image (II), discomfort remained low in all groups from
before to after treatment: groups B and T pooled, 1.2 (s.d.=1.2) to 0.79
(s.d.=0.8), t=2.4, P0.05; group B 0.920.44,
t=2.2, P=0.1; group T 1.7
1.4, t=0.99,
P=0.43; group R 1.4
0.7, t=1.5, P=0.28. For
the two ERP groups pooled, the low discomfort during neutral image (II) fell
significantly further after treatment.
The fall in discomfort during the cancelling OCD image (II) from before to after treatment was thus significant only after exposure, not relaxation. After treatment, although the cancelling image still reduced discomfort from both OCD and anxiety (non-OCD) image (I), this reduction was not right down to the low level rated during the neutral image (II).
Changes in imagery v. changes in scores on clinical
scales
Before treatment, during the OCD imagery, neither the amount of discomfort
it evoked nor the discomfort remaining after its cancellation correlated
significantly with clinical scores, respective correlations being: YBOCS
(r=0.42 and 0.00), WSA (r=0.33 and 0.34) or HRSD
(r=-0.02 and 0.15). Discomfort during the OCD image at baseline and
after its cancellation did not correlate significantly with post-treatment
YBOCS or WSA scores.
Change in clinical scale scores from before to after treatment
Available results for group B are for six patients (four who were in the
original group B and two who had group B's treatment after they had been in
group R without improving), for group T for three patients, and for group R
for four patients. Improvement from before to after treatment on the YBOCS
total score was, for groups B, T and R respectively, a mean of 9.1
(29.718.1=36%, t=9.1, P < 0.001), 2.7
(27.3
24.6=10%, P=0.057) and -4.2 (28.5
32.7=-15%). For the
two ERP groups B and T pooled, the fall in YBOCS score from before to after
treatment remained significant, from 28.3 (s.d.=5.1) to 20.3 (s.d.=5.8)
(t-4.5, P=0.002). The improvement on the WSA total score
after treatment was, for groups B, T and R respectively, a mean of 9.0
(19
10=47%, P=0.03), 2.0 (25
23=8%) and -1.2
(24.5
25.7). For the two ERP groups B and T pooled, the WSA score
improved significantly from a mean of 21 (s.d.=8.6) before treatment to 14.1
(s.d.=9.6) after treatment (t=-4.22, P0.003). The HRSD score
did not change for groups B and T pooled, the mean values being: before
treatment 12 (s.d.=8.5), after treatment 11.7 (s.d.=8).
Group R patients did not improve from before to after treatment (YBOCS
28.532.7; WSA 24.5
25.7; HRSD 8.3
20.3).
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DISCUSSION |
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The experimental method also had its intended specific effect after treatment. After exposure therapy, discomfort fell significantly during the OCD image but not during the anxiety (non-OCD) image (after relaxation therapy there was no change in discomfort during either image). This specificity of the drop in discomfort during particular imagery fits the specific decrement in treated symptoms that usually occurs with exposure therapy. Interestingly, initial discomfort evoked by OCD scenes did not predict clinical response to exposure therapy.
It is noteworthy that patients were able to evoke different types of imagery despite having to give brief subjective discomfort ratings at 30-second intervals during the imagery tasks. Both type of image and type of treatment had been randomised.
Caveats about the small numbers
Only tentative conclusions can be drawn from the clinical measures, because
of the small numbers of patients per cell. Exposure guided by BTSTEPS led to
significant improvement which was clinically meaningful, with patients
resuming more normal work and social lives. Gains from exposure guided by a
therapist were unexpectedly small, and might perhaps be due to some patients
having to change therapist half-way when their original therapist had to go on
maternity leave. The facts that relaxation (without exposure) guided by an
audio-tape and manual did not help patients, and that two patients who did not
improve with relaxation went on to improve with subsequent exposure guided by
BTSTEPS, fitted past results with OCD, in which relaxation was guided by a
therapist (Marks, 1987).
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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I.M.M., J.G. and L.B. have intellectual property rights in the computer system that guided exposure therapy.
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REFERENCES |
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Bachofen, M., Nakagawa, A., Marks, I. M., et al (1999) Self-treatment of obsessive compulsive disorder using a manual and a computer-conducted telephone interview: replication of a US-UK study. Journal of Clinical Psychiatry, 60, 545-549.[Medline]
Bech, P., Allerup, P., Gram, L. F., et al (1981) The Hamilton depression scale. Evaluation of objectivity using logistic models. Acta Psychiatrica Scandinavica, 63, 290-299.[Medline]
Goodman, W. K., Price, L. H., Rasmussen, S. A., et al (1989) The Yale-Brown Obsessive Compulsive Scale. II: Validity. Archives of General Psychiatry, 46, 1012-1016.[Abstract]
Greist, J., Marks, I. M., Baer, L., et al (1998) Self-treatment for OCD using a manual and a computerized telephone interview: a US-UK Study. MD Computing, 15, 149-157.[Medline]
Jacobsen, E. (1938) Progressive Relaxation. Chicago, IL: University of Chicago Press.
Lang, P. J. (1985) The cognitive psychophysiology of emotion: Fear and anxiety. In Anxiety and Anxiety Disorders (eds A. H. Tuma & J. C. Moser), ch. 7. Hillsdale, NJ: Erlbaum.
Marks, I. M. (1986) Behavioural Psychotherapy. Maudsley Pocketbook of Clinical Management. Bristol: John Wright.
Marks, I. M. (1987) Fears, Phobias and Rituals. New York: Oxford University Press.
Marks, I. M., Marset, P., Boulougouris, J., et al (1971) Psychophysiological accompaniments of neutral and phobic imagery. Psychological Medicine, 1, 299-307.[Medline]
Marks, I. M., Baer, L., Greist, J. H., et al (1998) Home self-assessment of obsessive-compulsive disorder. Use of a manual and a computer-conducted telephone interview: two UK-US studies. British Journal of Psychiatry, 172, 406-412.[Abstract]
Received for publication June 30, 1999. Revision received September 16, 1999. Accepted for publication October 3, 1999.
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