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St. John's Wort:
Future Treatment for Obsessive-Compulsive Disorder?
A small, open clinical study suggests that
St. John's wort (SJW) warrants further study as a treatment for
obsessive-compulsive disorder (OCD), an anxiety disorder characterized
by repetitive behaviors and/or thoughts (Taylor et al.,
2000). Numerous studies have shown that St. John's wort (Hypericum
perforatum L., Clusiaceae) is effective in alleviating mild
to moderate depression, possibly via effects on the brain's uptake
of the neurotransmitter serotonin. Recently, studies have shown
that serotonin-reuptake inhibitors (SRI) antidepressant drugs
(including clomipramine, fluoxetine, fluvoxamine, paroxetine,
and sertraline) are effective against OCD, leading researchers
to speculate about the potential of SJW as a new treatment for
the condition.
For the open-label study, the researchers
enrolled 13 people who had been diagnosed with OCD at least 12
months earlier. (One subsequently dropped out because of a rash.)
Participants received 450 mg SJW (standardized to 0.3 percent
hypericin) twice daily for 12 weeks. (The authors provided no
further details about the SJW preparation used.) At baseline and
one-week intervals thereafter, clinicians evaluated the participants
using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the
Clinical Global Impression of Improvement Scale (CGI). Participants
evaluated their own improvement using the CGI. At baseline and
one-month intervals, changes in depression were measured using
the Hamilton Rating Scale for Depression (HAM-D).
At endpoint (after 12 weeks or at the time
the subject left the study), participants had an average drop
of 7.4 points on the Y-BOCS. On the CGI scale, clinicians rated
42 percent of participants as "much" or "very much improved,"
50 percent as "minimally improved," and 8 percent (one person)
as unchanged. Participants' self-evaluations yielded identical
assessments. By all three of these outcome measures, SJW had a
highly significant beneficial effect - comparable to that observed
with clomipramine, other SRIs, and behavior therapy. Participants'
mean HAM-D scores also dropped significantly between baseline
and endpoint, although the authors noted that participants began
the trial with scores that did not indicate clinical depression.
SJW generally takes four to six weeks to
exert an antidepressant effect. Because a statistically significant
change in Y-BOCS scores was noted after only one week of treatment
in the OCD trial, the researchers suspect that a placebo effect
may have accounted for the dramatic improvement observed. However,
the treatment effect continued to increase over time, whereas
a genuine placebo effect typically diminishes. Future placebo-controlled,
double-blind studies are needed to resolve this question. Adverse
events included diarrhea (reported by three participants) and
restless sleep (in two participants). One dropped out in the first
days of the study because of a rash, leaving 12 participants.
The prescription drugs used to treat OCD generally have more serious
and frequent side effects, so larger studies supporting this new
indication for SJW could be welcome news to people affected by
the disorder.
Although SJW's primary mechanism of action
remains undetermined, laboratory research indicates that the herb
inhibits the uptake of other brain chemicals (dopamine and norepinephrine)
as effectively as it acts on serotonin. Most SRIs are more selective
in their mode of action, primarily blocking serotonin. Interestingly,
the SRI that appears most effective against OCD, clomipramine,
is also the least serotonin-specific. It is possible that SJW,
too, exerts its effect by acting on a broader group of neurotransmitters.
- Nancy Hoegler, Herb Research Foundation
[Taylor LvH, Kobak K. An open-label trial of St. John's wort (Hypericum
perforatum) in obsessive-compulsive disorder. Journal of
Clinical Psychiatry 2000; 61(8): 575-578.]
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