Placebos and their consequences in clinical and basic research : effects and possible ways to harness them

Locher, Cosima. Placebos and their consequences in clinical and basic research : effects and possible ways to harness them. 2017, Doctoral Thesis, University of Basel, Faculty of Psychology.


Official URL: http://edoc.unibas.ch/diss/DissB_12213

Downloads: Statistics Overview


While for adults, a plurality of studies examines placebo responses and potential
moderators in antidepressant trials, comparable investigations in pediatric and geriatric patients
are scarce. This is especially problematic since the efficacy and safety of antidepressants is
controversial in these sensitive populations: effect sizes are small and severe side effects such
as an increased risk of suicidal thoughts and behavior have been reported. Here, it has been
hypothesized that the lack of a consistent significant benefit of antidepressants over placebo
could be associated with an increased response to placebo. Therefore, it is worth considering
whether the potential of placebos can be harnessed without undermining patients’ autonomy
through deception.
The emphasis of the current dissertation was twofold: first, to investigate the efficacy
of placebos and potential moderators in pediatric and geriatric patients. Second, to
experimentally test the necessity of deception. For this reason, two different statistical
approaches were indicated. For the first aim, a meta-analytic approach was applied in order to
assess differences between antidepressant and placebo interventions in pediatric major
depressive disorder (MDD), anxiety disorders, obsessive-compulsive disorder, and
posttraumatic stress disorder (Locher, et al., 2017; Study I), as well as in geriatric MDD,
dysthymia and minor depression (Locher et al., 2015; Study II) along with variation in placebo
responses and moderators. For the second goal, a basic research approach was chosen in order
to compare the effects of openly prescribed placebos with a deceptive placebo administration
in a standardized heat pain experiment with healthy participants (Locher, Frey Nascimento,
Kossowsky, Meyer, & Gaab, 2017; Study III). Here, basic research represents an excellent way
to experimentally compare these treatments in accordance with ethical principles.
The meta-analyses revealed that antidepressants are more effective than placebo at
treating MDD in children and adolescents (Hedges’ g = 0.20; Study I), as well as in elderly
people (Hedges’ g = 0.37; Study II). However, the effects were only small and did not reach
the proposed cut-off for clinical significance. Also, placebo responses in depressed youth
(Hedges’ g = 1.57; Study I), as well as in depressed elderly (Hedges’ g = 0.96; Study II) were
significant and substantial. Findings of the heat pain experiment with healthy participants
revealed that open-label placebos do not differ in their effects from deceptive placebos in
subjective outcomes (i.e., heat pain intensity ratings: p = .136 and heat pain unpleasantness
ratings: p = .481; Study III).
Placebo responses are large and meaningful in children, adolescents and elderly people
with depression. Pediatric as well as geriatric patients seem to respond well to clinician contact
that promotes the therapeutic alliance and other common factors such as the patients’
expectations and hopes of improvement. Furthermore, the ubiquitously assumed necessity of
concealment in placebo administration is questioned and new ways in order to harness the
potential of placebos should be considered.
Advisors:Gaab, Jens and Greifeneder, Rainer
Faculties and Departments:07 Faculty of Psychology > Departement Psychologie > Health & Intervention > Klinische Psychologie und Psychotherapie (Gaab)
UniBasel Contributors:Locher, Cosima and Gaab, Jens and Greifeneder, Rainer
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:12213
Thesis status:Complete
Number of Pages:1 Online-Ressource (47, ca. 100 ungezählte Seiten)
Identification Number:
edoc DOI:
Last Modified:22 Jan 2018 15:53
Deposited On:03 Oct 2017 14:47

Repository Staff Only: item control page