| Project "Placebo and Nocebo: effects and phenomena in general practice" |
Symposion
"The Problem of Placebo and therapeutic effectiveness" or the "Hunger for healing – enigma"10 Hypotheses
MOMBURG, M. (Eggeland-hospital Bad Driburg);
G.FISCHER (Department of Primary care at the University of Hannover; Germany)
- Chapter 1: Introduction
- Chapter 2: Methods
- Chapter 3: Results
- Chapter 4: Consequences
- Literature of placebo-specialists
Chapter 1: Introduction
The terms placebo, nocebo, placebo effect, placebo phenomenon, placebo medicine have a
considerable role to play in the present discussion about reduction of costs in Health
Care.
Physicians and laymen maintain that 30% of every therapeutic effect should at least be
based on the "placebo effect".
In spite of their very high practical importance placebo phenomena do not play a part in the education of medical students and are no systematic subject of discussion in medical science.
In order to achieve a better understanding of the phenomenology of placebo effects in
therapeutic relationships and to maximalise the outcome of student´s education in general
practice, we (the Director of the Eggeland-Hospital and the Department of Primary Care,
University of Hannover, Germany) organized a project "Placebo and Nocebo: effects and
phenomena in general practice".
Chapter 2: Methods
The methods used to produce the following results were:
- Evaluation of the literature
- Specialist-Interviews
- A symposium of placebo specialists at Bad Driburg Friday 13th-Sunday 15th June 1997
The specialist interviews were carried using the method of
"qualitative-empirical-social investigation" and a modified
"Delphi-technique".
The aim was to look for common principles; to identify representative opinions and
structures of relevancy and reality of placebo effects.
From September 1996 till March 1997 19 specialists of placebo (see appendix) in Germany, Austria and Switzerland were visited by the author and conversations based on a structured interview with standardized questions were carried out.
| Questions for the interview: |
|
These specialists were identified by publications, letters and papers in medical science. They have worked on the therapeutic effectiveness and the efficacy of therapeutic methods in conventional, complementary medicine and psychotherapy from different standpoints (see appendix).
The interview time ranged from 1 ½ to 10 hr per conversation.
For 4 of the interviews technical recordings were not possible, because the participants
would not give theit consent. However these interviews were then reconstructed from
memory.
Every interview was then evaluated sentence by sentence according to statements about definitions, theories, opinions on the subject "specific or nonspecific effects, scientific works for solving the placebo problem in future, opinions on the role of placebo effects in the different medical methods, training for understanding the placebo-effects in the education of medical students.
The statements in these subsections were arranged into comparison groups of medical fields such as internal medicine, psychiatry, molecular biochemistry, methodology of outcome etc. to establish whether there may be a connection between theory and specific medical professions.
In this manner, material resulted for evaluation from approximately 800 typewritten
pages.
Chapter 3: Results
First results of this project will be shown in this article.The opinions, statements and presumptions were matched with references found via the specialists, throug Medline, in medical journals and tested for plausibility.
3.1) During the systematical check and classification of publications about the placebo subject we have found two emotionally split fractions.:
- The "Placebo forte group" claims that placebo effects account for two thirds of the therapeutic effects (Roberts 1993),
- The "sceptical group" claims that the existence of placebo effects should first be proved, (Kienle, Kiene 1993)
Summarized the following Synopsis of different or similar theories for the placebo
phenomena were found:
Learning model, classical conditioning, and a refined learning model of expectation;
endomorphin mediated effects; the common factors model of therapeutic rituals; theory of
cognitive dissonance; control theory, learning of self perception theory; "Aura
curae", and a model of attribution and a lot of similar theories, which are based
partially on these or similar state things in various ways.
3.2) From the specialist interviews, unambiguous, valid and distinct statements for the definitions of placebo terms were not derived, even though the phrases most frequently used were similar to the classical definitions of Shapiro or Brody [1].
Some original quotations:
"Everybody knows what a placebo is, until you ask him""A Placebo is an agent, whose assumption is not consistent with the art of natural science, so that its effect could be proved for the purpose of treatment by accepted law of causality"
However, the ambiguous definitions are understandable in connection with the used theories. The position of the specialist in the field of medicine apparently seemed to determine his point of view.
The definition of placebo terms can also result from further clarification in the sense of an inductive philosophical procedure. Many misunderstandings, which are a result of the placebo problem, derived from determined definitions of the terms according to the principle: "What can not be, must not be"
I was struck by one definition:
|
3.3) Evaluation of the dimension of the placebo effects in different
medical fields.
Chapter 4: Consequences
1.Hypothesis
The placebo phenomenon cannot be explained by the common theories and therefore it might
be reasonable to collect all the words and terms, which are used in the theories and to
handle them with the same level of importance.
An arrangement system then results from the idea that specific aspects in papers, determine connected"spaces", in which placebo phenomena occur:
1) If specific conditions exist under the aspect of the therapist´ role
2) If specific conditions exist from the viewpoint of the patient
3) If specific conditions are available in the healing environment.
4) If the relationship between therapist and patient is subject to specific conditions.
5) If these relationships happen in ritually dominated surrroundings and at a specific time.
These limiting conditions implied the existence of the placebo effects and were scrutinized in concrete scientific papers [2].
2.Hypothesis:
Placebo is no deception but it triggers self-healing
List and visualisation of the terms found in the explanatory theories:
My idea was to extract phenomena of placebo and nocebo independently from the definition of the placebo terms and to use an optimized overall view, which may be possible in a healing environment with the aim:
"The situation should be analyzed and changed for the better",
And in almost exactly the same way to look for extremely negative points in medical situations with the aim:
"This situation should be understood, analyzed and then avoided! Look for positive "placebo-milieu"!"
As for routine reality in therapeutic relationships, parts of both effects, placebo and nocebo principles are always present. The therapeutic effectiveness and the efficiency result is like the integral calculation of the positive and negative effects on an individual base of both, the patient and the therapist!
In the diagrams " Placebophenomena and therapeutic effects A-D" the terms given are divided into the fields explained above (or below!):
What is accumulated under the term Placebophenomena:
| Diagram I A: Placebophenomena and therapeutic effects |
I.: Indefinable assumed
backgroundeffects:
II.: Common factors of therapeutic rituals:
|
|
|
| Diagram I B: Placebophenomena and therapeutic effects |
| III.: From the point of view of the
therapist: |
|
|
| Diagram I C: Placebophenomena and therapeutic effects |
| IV: Effects from the surroundings and
situation: |
|
|
| Diagram I D: Placebophenomena and therapeutic effects |
| V: From the point of view of the sick
person: |
3.Hypothesis:
Nocebo is not only a cause but often a result
Synopsis of Nocebo phenomenona in the therapeutic situation which reduce the
therapeutic effectiveness, causing deteriorating symptoms or even new ones.
The nocebo effects become clear by giving the terms of placebo-phenomena a negative
sign indicating the opposite: ( e.g.: inaccurate information instead of precise
information or illness profit instead of compensation for illness)
| Diagram 2: Nocebo phenomenona and therapeutic effects |
| The underlined terms
(blue arrows in the diagram) are part of nocebo phenomena and toxicopy mechanisms
(similar parallel poisoning symptoms without concrete toxic load from the evironmental
field; Kofler) I.: Indefinable assumed background effects:
II.: Common factors of therapeutic rituals:
III.: From the point of view of the therapist:
IV: Effects from the surroundings and situation:
V: From the point of view of sick person:
|
4. Hypothesis
What about the idea of"natural course"?
But in this situation we have to be aware of a very important background problem: Not
every feeling is a symptom, not every symptom means an illness and one´s feeling in
uncertain situations differs, when somebody asks: "how are you feeling?". That
modifies the objective reality. So we have to take a step back into a normal healthy
situation:
| The phenomena "spontaneous healing", natural course", "selfhealing" result from the maintenance of health and are proof of the ability for the determined genetic system to select or to repair damaged morphological structures and to stabilize the balance of integrated physical and psychological biological systems. |
Therefore "spontaneous healing" can not be seen as a part of the placebo effect. The emergent potential of the placebo principle becomes reality in the case of symptoms, which indicate a feared illness.
In this case the following
"structure" of healing process is necessary:
|
5. Hypothesis:
Placebo rate and group design
From this point of view the attempt of dissociating the "true placebo effect"
from the "natural course" might be difficult.
|
Consequences: These unidentifiable effects may only be evaluated by comparison with
an untreated group.
But in an untreated group the individual person may perhaps become effected by
placebophenomena outside the medical setting, for example by reading a philosophical or
theological text.
From the view of an individual, sick feeling person these medical science results are
without any relevance, because he feels that very different methods could be effective, if
the therapist, the relationship and the surroundings are optimized.
The patient trusts the competence of the therapist to choose the most effective
methods.This predicament triggers the healing supportive submission; in other words,
regression into a selfhealing supportive prevailing mood. But the patient is mostly unable
to analyse this situation rationally, therefore he is susceptible to manipulation. So you
can see the result as either a placebo effect or a nocebo effect.
6.Hypothesis
The philosophical dilemma
So the development of a special theory of medicine for its own sake, independent of
physics and chemistry, might be the most important.
That would be more essential for the progress of medicine than pseudo-scientific trials
on the level of nominalism with psychological, reductionist, introjectionist
materialisation, which hides itself frequently behind the name "natural scientific
orientated medicine" (Schmitz; Neue Phänomenologie)
Diagram 3: Inner world and reduced body
Consequences: An attempt to understand
7. Hypothesis
The integrated placebo/nocebo-principle
The placebo is nothing "disreputable" or similarly "parasitical," but
within the placebo-effect is concealed something, which could be called the "Healing
power of nature", "power of self-healing" or "power of
self-stabilization" (Pirlet)
This is an expression of an evolutionary developed and constantly functionable
possibility for repairing and protection to effect
(selection of damaged proteins; Pirlet),
1) language information, (possibly one word = the "Flash" of Balint as a
positive result at that moment),
2) signs and symbols of healing, Schonauer, Uexküll.
They are an inseparable content of the therapeutic situation)
- In western medicine the role of shaman i.e. to be both priest and witchdoctor, is separated into specific therapist roles such as psychotherapist, hypnotist, surgeon, homeopath or acupuncturist.
- The role of shaman to be priest is separated in the different types of priest and monk within the various religions.
They all use the concealed placebo principle.
On each level, from the cell to the social communities, the complexity and the possibilities of healing processes increase, but also the risk of negative effects. So on the one hand we can understand healing effects and on the other it is an aid for understanding an unsuccessful attempt of healing, which results in a new illness. This instead is an alarm signal in the sense of the need for early diagnosis for the social community.
| So the placebo phenomenon differentiates from nocebo phenomenon only in the experience of therapeutic effectiveness from the view of patient or through the appearance of therapeutic efficiency from the view of the therapist. These views may differ. This in my opinion is the integrated placebo/nocebo-principle. This means Placebo-principle = good from the one side and Nocebo-principle= bad from the other side. The same mechanism with different results. |
Diagram 4: An example: Nocebo phenomenon in the therapeutic situation
All conditions for therapeutic effectiveness look optimized, but anxiety inducing information e.g.a. misleading description about side-effects leads to NON-compliance.
8.Hypothesis
Effectiveness and objective reality
The perception and the explanation for the assumption of so-called increasing
effectiveness does not have to be correct and true, measured from the view of an
"objective point of reality", but subjectively plausible for both the patient
and the therapist. It arises from the subjective compulsion to assess, similarly a
positive prejudice. So perhaps positive thinking results in self-stabilizing effects,
although it is a type of self-deception.
Then the phenomenology of the placebo principle, e.g. the positive thinking self-deception or the belief in the therapeutic myth can induce the "healing effect" by autosuggestion using unknown psychophysical ways.
We can call this a structural gain, which increases the self-effectiveness.
This in turn triggers the self-healing potential.
If there is inaccurate information, which triggers anxiety, the subjective compulsion to
assess leads, by negative self-deception, to the nocebo phenomenon.
That could be similar to the breathlessness of an allergic asthma patient, who cannot understand, that his damaged biological system tries to protect him against further intoxication by an allergic substance. After a few years the result is, that the allergic substance is no longer necessary, because the asthma illness has become fixed. A positive protecting system changes into an autoaggressive, uncontrolled system, which we diagnose as a disease.
(The connection of these mechanisms with the process of homeostasis in biological systems can be seen in the very strong emotional conflicts between mainstream medicine and complementary medicine.)
9. Hypothesis
"Hunger for healing" enigma
The placebo principle which is unconsciously integrated in every therapeutic relationship
is only a special case for the so called basic principle of survival, and could be called
hunger for healing, like the hunger for natural balance ( Homeostasis); for wellness, for
satisfaction, for understanding, for recognition; for personal closeness, for
relationship, for community; for affiliation; for peace of mind and for the meaning of
life.
Interestingly this explanation of the placebo phenomena might be confirmed through the similarity of the theories for understanding phenomena such as "hunger and thirst", "pain and lust (desire)", which concern the mechanisms of expectancy, learning, conditioning and biochemical neurotransmitters.
10. Hypothesis
"Transitional object"
The placebo principle "as if" has either " genetic preconditioning" or
the preconditioning of genetic information. Its individual arrangement in a concrete
person originates from the first relationship between an infant and its mother.
The "good-enough" mother gives the first chance for development, when she begins to separate herself for a short time. The infant who, up to this point, has been living in a so called "primary complex," needs a substitute mother in order to bear this separation. This takes the form of an object e.g.a. soft toy like a teddy-bear, a blanket, or some other objects of comfort. Winnicott called such an object "transitional object". The "transitional object" remains as a stable principle and is necessary for regression, which is the requirement for the possibility of the so-called "Integrated placebo/nocebo principle" entering into a therapeutic relationship.
So the prescription, the remedies or the emotions or the attitude of the therapist are
symbols for the transitional object. This means: The therapeutic relationship uses the
"motherliness" of the therapists. The fatherliness of the therapists can be
engaged, when guidance and careful detailed information is given.
That might be one way for better understanding of the toxicopy principle, when it is
missing.
| Consequences: |
| The above explanations are hypotheses for further discussion regarding this topic. At this stage of our project, at least the understanding can be used for optimizing the therapeutic effectiveness, independent of the specific efficacy of the method, and for avoiding negative effects, which we call "Non-compliance". |
MOMBURG M.: Eggeland-hospital, 33014 Bad Driburg, Germany, Bahnhofstraße 1
Tel: 00 49 5253 9860; Fax: 00 49 5253 986100
Email: momburg.eggelandklinik@t-online.de;
Internet; www.eggeland-klinik.de
Specialist interviews:
- Prof. Dr. Dr. Schaefer, emer. Physiologie und Sozialmedizin (Heidelberg);
- Dr. Dr. Walach, Homöopathieforschung im Rahmen der Rehabilitationsmedizin (Freiburg);
- Prof. Dr. Fahrländer, emer. Internist und Gastroenterologe (Basel);
- Prof. Dr. Pletscher, emer. jetziger Präsident der Schweizerischen Akademie der Wissenschaften (Basel);
- Priv.Doz. Dr. Caspar, Klinische Psychologie (Bern, "Psychotherapie zwischen Konfession und Profession" Grawe);
- Prof. Dr. Uexküll, emer. Psychosomatik (Freiburg);
- Prof. Dr. Wirsching, Psychosomatische Medizin und Psychotherapie (Freiburg);
- Dr. Kienle/Dr. Kiene, Institut für angewandte Erkenntnistheorie und medizinische Methodologie (Freiburg, "Der sogenannte Placeboeffekt");
- Priv.Doz. Dr. Resch, Kurortmedizinisches Forschungsinstitut (Bad Elster, "the true placeboeffect");
- Prof. Dr. Kofler, Sozialmedizin (Innsbruck, "Toxicopie");
- Dr. Meißel, Psychiatrie (Gugging/Wien, "das Übergangsphänomen");
- Prof. Dr. Langer, Psychiatrie (Wien; "Aura curae");
- Prof. Dr. Engelhardt, Innere Medizin (Kiel);
- Prof. Hermann Schmitz, emer. Philosophie "Neue Phänomenologie", (Kiel);
- Dr. Dipl.Psychologe Mumm, Klinik für biologische Medizin und Onkologie (Freiburg);
- Dr. Dr. Schonauer, Psychiatrie (Münster; "Semiotik")
- Prof. Dr. Pirlet, emer. Innere Medizin, Naturheilkunde und Diätetik (Frankfurt; "die Heilkraft der Natur")
- Prof. Dr. Habermann, emer. Klinische Pharmakologie, (Gießen;
"Placebo-Nocebo-Quadrupol")
Literature of the placebo-specialists:
Caspar, F.: Im Streit um die richtige Sicht in der Wirksamkeitsforschung; Psychotherapie Forum 1 (1993) 96-99
Caspar, F.; Th. Rothenflush; Z. Segal: The Appeal of Connectionism for Clinical Psychology; Clinical Psychology Review 12 (1992) 719-762
Engelhardt, K.: Plazebos, Alternative Medizin und die Arzt-Patient-Beziehung; in Feiereis, H.; R. Saller (ed.): Psychosomatische Medizin und Psychotherapie, Hans Marseille Verlag München (1995) 199-209
Ernst, E.; K.L.Resch: The science and art of the placebo-effect; Current therapeutics (1994) 619-621
Ernst, E.; K.L.Resch: Concept of true and perceived placebo effects; BMJ 311 (1995) 551-553
Fahrländer, H.; P. Truog: Plazebowirkung und Alternativmedizin. Internistische Praxis 4 (1990) 763-772
Fahrländer, H.: Die Placebowirkung; Therapiewoche Schweiz 9 (1993) 569-572
Flick, U.: Qualitative Forschung - Theorie, Methoden, Anwendung in Psychologie und Sozialwissenschaften; rowohlts enzyklopädie (1995) 109-110
Habermann, E.: Wappen schlägt Zahl: Die biologische Grundlage des Placebo und Nocebo; Futura 3 (1996) 179-188
Kiene,H.: Komplementärmedizin - Schulmedizin. Der Wissenschaftsstreit am Ende des 20.Jahrhunderts. (2.,durchgesehene und erweiterte Auflage). Schattauer Stuttgart
Kiene, H. : Kritik der klinischen Doppelblindstudie. (1993) MMV Medizin Verlag München
Kiene, H.; M.Kalisch: Wissenschaftliche Dogmen bei der Nachzulassung von Arzneimitteln. Deutsche Apotheker Zeitung 136 Jahrg. Nr 28 (1996) 17-22
Kienle, G.S.: Der sogenannte Placeboeffekt - Illusion, Fakten, Realität, (1995) Schattauer Stuttgart
Kienle, G.; H. Kienle: Placeboeffekt und Placebokonzept - eine kritische methodologische konzeptionelle Analyse von Angaben zum Ausmaß des Placeboeffekts. Forschende Komplementärmedizin 3 (1996) 121-138
Kofler, W: Toxikopie: Placebo im Umweltbereich - Wissenschaftstheoretische Konsequenzen aus erfahrungswissenschaftIichen Tatsachen in : Stacher, A.: Placebo und Placebophänomen Facultas Wien (1995) 100-148
Langer, G.: Placebo, Placebophänomen und Aura curae: Eine kritische Erörterung. in Stacher, A.: Placebo und Placebophänomen. Facultas Wien (1995) 21-31
Langer, G.: Principia Medica humana unter besonderer Berücksichtigung von Placebo, Arzt-Patient-Beziehung und Compliance; Vortrag am 9.3.1997 an der Wiener Akademie für Ganzheitsmedizin
Meißel, Th.: Die Bedeutung und Funktion des Placebo aus psychoanalytischer Sicht. in Stacher, A.: Placebo und Placebophänomen. Facultas (1995) 71-99
Meißel, Th.: Placebo, Compliance und der Traum von Irmas Injektion; Edition pro mente Linz (1996)
Oepen, I.: Zur rechtlichen Beurteilung paramedizinischer Heilverfahren. Versicherungsmedizin 44 (1992) (23-29)
Oepen, I.:Besondere Therapierichtungen, Gleichberechtigung neben der Schulmedizin?. Deutsche Apotheker Zeitung 134.Jg. 32 ( 1994) 42-53
Oepen, I.; O. Prokop: Außenseitermethoden in der Medizin. Wissenschaftliche Buchgesellschaft (1994)
Oepen, I.: Das Problem der unkonventionellen medizinischen Methoden - dargestellt am Beispiel der "besonderen Therapierichtungen". Z.f.Gesundheitswiss. 3 (1995) 111-129
Pirlet, K.: Die Heilkraft der Natur - Ein Ausleseprozeß auf protein-molekularer Ebene; Erfahrungsheilkunde 11 (1996) 848-858
Pletscher, A.: Alternativmedizin: Glaube oder Wissenschaft? Internistische Praxis 1 (1991) 149-161
Schaefer, H.: Was heißt Heilen? Die Bedeutung der spezifischen und der unspezifische Therapie. in Oepen, I. (ed.): An den Grenzen der Schulmedizin. Dtsch.Ärzte-Verlag (1985) 363-375
Schaefer, H.: Das Prinzip Psychosomatik. Verlag für Medizin Dr. Ewald Fischer (1990)
Schaefer, H.: Die wissenschaftliche Medizin zwischen Mystik und Materialismus. In Köbberling, J.: (ed.) Die Wissenschaft in der Medizin. Schattauer Stuttgart (1993) 15-26
Schaefer, H.: Altern und Sterben - Gedanken zu statistischen Zahlen. Z Gerontol Geriat 28 (1995) 285-292
Schaefer, H.: Schwache Wirkungen als Cofaktoren bei der Entstehung von Krankheiten. Springer Verlag Berlin (1996)
Schmitz, H.: Thesen zur phänomenologisch-philosophischen Fundierung der Psychotherapie in: Kühn, R.; H. Petzold: Psychotherapie & Philosophie - Philosophie als Psychotherapie?; Junfermann Verlag Paderborn (1992)
Schmitz, H.: Leib und Gefühl - Materialien zu einer philosophischen Therapeutik Junfermann Verlag Paderborn (1989)
Schmitz, H.: Der gespürte Leib und der vorgestellte Körper; in: Großheim M.(ed.): Wege zu einer volleren Realität - Neue Phänomenologie in der Diskussion; Akademie Verlag Berlin (1994) 75-91
Schmitz, H.: Der Placebo-Effekt im Licht der Neuen Phänomenologie, Veröffentlichung in Vorbereitung
Schonauer, K.: Das Plazebo-Problem; in Bühring, M.; F.H. Kemper (ed): Naturheilkunde; Springer Berlin (1994) Loseblattsammlung, unveröffentliches Manuskript
Schonauer, K.: Semiotic Foundations of Drug Therapy-The Placeboproblem in a New Perspective, Mounton de Gruyter, Berlin (1994)
Uexküll von, T.: Das Placebo-Phänomen. In: Adler, R. H.; J. M. Herrmann, K. Köhle, O. W. Schonecke, Th. von Uexküll, W. Wesiak: Psychosomatische Medizin. Urban und Schwarzenberg, München-Wien-Baltimore (1996) 363-369
Walach, H.: Homöopathie - Heilung mit Nichts? Psychologie heute (9/1993) 40-49
Walach, H.: Which Placebo to Use? The Problem of Using a Proper Placebo for High Dilution and succussion Studies. The Berlin Journal on Research in Homoeopathy 1, Vol. 1, No. 3 (1991) 174
Walach, H.: Wissenschaftliche homöopathische Arzneimittelprüfung-Doppelblinde Crossover-Studie einer homöopathischen Hochpotenz gegen Placebo; Haug (1993)Wirsching, M.; L. Frölich; W. Georg; B. Haas; F. Hoffmann; J. Riehl; G. Schmidt; P. Schmidt; H. Stierlin; B. Wirsching: Krebs im Kontext. Patient, Familie und Behandlungssystem. Klett-Cotta Stuttgart (1988)
Wirsching,M.: Psychosomatische Medizin. Konzepte- Krankheitsbilder- Therapien.
Verlag C.H. Beck München (1996)
2) A placebo, when used as a control in experimental studies, is defined as a substance or procedure that is without specific activity for the condition being studied.
3) A placebo effect is defined as the psychological or psychophysiological effect produced by placebos".
BRODY 1980: " A placebo is: 1) a form of medical therapy, or an intervention designed to simulate medical therapy, that at the time of use is believed not to be a specific therapy for the condition, for which it is offered and that is used either for its psychological effect or to eliminate observer bias in an experimental setting.
2) (by extension from 1) a form of medical therapy now believed to be inefficacious, though believed efficacious at the time of use."
[2] Roberts A.H. et al: The power of
nonspecific effects in healing: Implications for psychosocial and biological treatments;
Clinical Psychology Review 13 (1993) 375-391
Bergmann JF. et al: A randomised clinical trial of the effect of informed
consent on the analgesic activity of placebo and naproxen in cancer pain; Clinical Trials
and Meta-Analysis 29 (1994) 41- 47
Amigo I. et al.:The effect of verbal instructions on blood pressure
measurement; Journal of Hypertension 11 (1993) 293-296
Uhlenhuth E. H. et al.: Drug, Doctor's Verbal Attitude and Clinic Setting
in the Symptomatic Response to Pharmacotherapy; Psychopharmacologia (Berlin) 9, (1966)
392-418
Gryll S.L. et al.: Situational Factors Contributing to the Placebo
Effect; Psychopharmacology 57 (1978) 253-261