Jim et al. - Re: Jim Clark's question # 4 below, there is a modest literature
comparing "antidepressants" (I place the word in quotations, as there is now
increasing consensus that these are not medications for depression per se) with
"active placebos," which create many/most of the same side effects (e.g., dry
mouth) as traditional antidepressants. My understanding is that atropine is
the most frequently used active placebo in this literature.
See below for a link to a 2009 Cochrane Collaboration review compariing
antidepressants, in this case the older tricyclics, with active placebos. This
certainly will not be the final word on the issue, as the question remains
highly contentious.
http://psychrights.org/research/Digest/CriticalThinkRxCites/Moncrief2004.pdf
For TIPSters who can't readily access the PDF, here are the bottom line
results and conclusions from the review:
Main results
Nine studies involving 751 participants were included. Two of them produced
effect sizes which showed a consistent and statistically significant difference
in favour of the active drug. Combining all studies produced a pooled estimate
of effect of 0.39 standard deviations (confidence interval, 0.24 to 0.54) in
favour of the antidepressant measured by improvement in mood. There was high
heterogeneity due to one strongly positive trial. Sensitivity analysis omitting
this trial reduced the pooled effect to 0.17 (0.00 to 0.34). The pooled effect
for inpatient and outpatient trials was highly sensitive to decisions about
which combination of data was included but inpatient trials produced the lowest
effects.
Authors' conclusions
The more conservative estimates from the present analysis found that
differences between antidepressants and active placebos were small. This
suggests that unblinding effects may inflate the efficacy of antidepressants in
trials using inert placebos. Further research into unblinding is warranted.
...Scott
________________________________________
From: Jim Clark [[email protected]]
Sent: Wednesday, September 14, 2011 11:00 PM
To: Teaching in the Psychological Sciences (TIPS)
Subject: Re: [tips] Blinded or Blind Studies
Hi
James M. Clark
Professor of Psychology
204-786-9757
204-774-4134 Fax
[email protected]
>>> Mike Wiliams <[email protected]> 14-Sep-11 1:10:07 PM >>>
>Outpatients still get dry mouth and constipation.
What underlies my
criticism is that humans will reason their way through a study
and if they are given basic information like side effects, they will
infer the
presence of treatment or placebo. All the great research guides assume
that the
subjects are passive agents of the treatment research design. The idea
that they
would interact with the design causes great problems in our own inferences.
I generalize to all studies simply because I cannot think of a way
anyone, including
myself, can get around the problem. When problems like this exist the
very human
researchers put their collective heads in the sand and say its not so.
We can never be confident that any study of a psychological intervention
ever worked.
We have to accept that none of these interventions will ever meet an
objective
standard of empirical support.
Constipation trumps all.
*******************
Jim - a couple of observations.
1. Mike W. appears to leap from side effects ("constipation") being inevitable
and detectable in drug studies to "any study of a psychological intervention"
without recognizing that the notion of "side effects" would be irrelevant to
many forms of psychological intervention. For such non-drug interventions, it
would seem to me that he would have to argue that participants can always
distinguish whether they are in the treatment group or the control group, no
matter what the form of the control group. But wouldn't some sorts of Control
(e.g., talking therapies) be difficult to identify as neutral for all but
knowledgeable clients familiar with effective psychotherapies? After all,
there are therapists who are convinced that certain ineffectual therapies work,
so why wouldn't participants think the same?
2. Looking just at the participant side of things, Mike W.'s model would seem
to require a sort of double placebo effect. That is, there is a placebo effect
when given an inert pill that has no side effects, but this effect is enhanced
when the placebo has side effects noticeable by the patient. This would appear
to lead to the prediction that pills with greater side effects will be more
effective than those without. Is there any evidence for this position?
3. On the criterion side, not all outcomes are subjective in nature are they?
What is known, for example, about suicide rates for people with depression who
are treated versus not treated in various ways? And are there not objective
criteria for diverse disorders, such as social anxieties or various phobias? I
mean the person either approaches and touches a spider or not after treatment,
right? And someone with anger management and aggression tendencies either gets
into fights or not. ...
4. It is not obvious to me that the problems Mike W. identifies are in fact
insurmountable (at least in theory). Could not, for example, a placebo be
created that itself produced noticeable side effects, but without the active
ingrediant in the treatment drug? Or, is it not possible to determine whether
participants, observers, or whoever guessed what condition participants were in
and see if this contributed to the outcome measures? The latter approach would
apply to both medication and psychological interventions.
5. Science is full of examples of things that people said were impossible to
do. And certainly if we were able to inquire of people even a few centuries
ago about today's scientific knowledge, I would fully expect them to be
astounded and say "that's impossible to know." Suggests to me that history is
not supportive of the pessimistic "it can't be done" position Mike W. endorses.
Take care
Jim
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