PSYCHOLOGY AND PHYSICAL THERAPY

killer, despite the fact that the reduced pain in trial two was actu- ally the result of a lower intensity pain induction procedure.

THE PLACEBO EFFECT WITHIN THE BIOMEDICAL MODEL The few experiments reviewed above represent only a very small snapshot of a large and varied literature attesting to the power of the placebo effect. Given this evidence, it is perhaps surprising that the effect is still a matter of some debate and under-used in therapeutic settings. Part of the reason for the scepticism of prac- titioners is that the placebo effect does not fit epistomologically into the biomedical model of objectivity (see figure 1).

Health Healthy tissue Mediator Disease Injury Figure 1: Some aspects of sports injury within the linear biomedical model

The biomedical model relies heavily on the assumption that disease is the result of biological processes, and as a result, all treatments should be based around changing the underlying pathophysiology (11). Subsequent treatment is thus based around a physical intervention to readdress the diagnosed deficiency. Such a tissue-based model for diagnosis and treatment is increas- ingly being questioned (12). The biomedical model does not account for thoughts, feelings and attitudes and therefore does not identify that somatic processes such as pain or inflammation may be strongly influenced by psychological factors. Jeffels and Foster (13) suggest that many existing assessment techniques are solely based upon this biomedical model with the aim of trying to discover where the fault in the tissue lies and thus does not account for psychological factors.

THE PLACEBO EFFECT WITHIN THE BIOPSYCHOSOCIAL MODEL Ogden (11) suggests that a more holistic approach is the biopsy- chosocial perspective, which considers the clinical potency of social and psychological factors that may facilitate the desired clinical outcomes (eg. the patient’s symptoms decrease). In this model an intervention at any system level may serve to alleviate the condition, for example, reduced training load, psychothera- py/cognitive-behavioural therapy (CBT), or anti-anxiety measures such as maintenance of sport-related social contacts or even, if necessary, anxiolitic drugs. From this biopsychosocial perspective of medical care it is clear that all sports rehabilitation treatments occur within a psychological and social environment and must respect factors such as the therapeutic relationship between client and practitioner. DiBlasi et al (14) suggest the characteris- tics of this relationship critically influence the treatment out-

Bio

Injury mechanism Tissue damage

Physical therapy

Reduced pain Normal function Psycho

Anxiety Pain

CBT interventions Placebo effects

Anxiety reduction Reduced pain

Social

Withdrawal from training

Loss of athletic identity

Maintenance of social contact with sport group

Figure 2: Some aspects of sports injury within the interactive biopsychosocial model

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comes, whether they are specific to the treatment delivery or unintended (non specific) ‘placebo effects.’

SUPPORT FOR THE BIOPSYCHOSOCIAL MODEL A growing body of research supports Ogden and DiBlasi’s argu- ment. Recent findings suggest that the placebo effect is not only driven by tangible objects such as tablets or injections, but by such psychosocial factors as predicted by the biopsychosocial model. Gracely et al (15) found that a patient’s expectations influenced clinical outcomes. However, unlike the research high- lighted above, in this study it was the beliefs of the doctors, not the patients, that was under examination.

Patients were placed in three experimental conditions; analgesia, placebo, and naloxone (naloxone is an opiate agonist that would be expected to increase pain). Patients were told that their treat- ment would either reduce, have no effect on, or increase pain. Doctors were also placed in two experimental groups, group one believing patients would receive any one of the three substances (ie. doctors in group one believed that patients had at least a chance of pain relief), and group two believing patients would receive only placebo or naloxone (ie. doctors in group two believed that patients had no chance of pain relief). Doctors were instructed as to how to behave with patients. Unbeknown to doc- tors, all patients were in fact given a placebo. Results indicated that patients whose tablets were administered by doctors in group one experienced greater pain relief than those whose tablets were administered by doctors in group two. It could therefore be con- cluded that the behaviour and communication of doctors in group one in some way conveyed greater expectation of imminent pain relief than that of doctors in group two. Similarly Staats et al (16) found that patients exposed to positive suggestions prior to pain stimulation had a significantly higher pain tolerance and thresh- old than the control group (a finding that perhaps explains why doctors tend to say ‘this won’t hurt a bit’ just before they plunge a needle into your arm). Conversely those exposed to negative suggestions prior to pain stimulation had lower pain threshold and tolerance than a control group. Similar findings have been reported by French (17), who suggested that the mere act of vis- iting a physiotherapy department and receiving attention by the therapist could itself reduce anxiety and relieve pain. Charman (18) described therapists themselves as a treatment modality, applied directly to the mind of the patients with the outcome being a change in intensity and perception of the experienced pain. Perhaps best summarising this area of research are the find- ings of Benedetti (19), who reported that a placebo administered by a doctor was actually more powerful than a ‘real’ drug admin- istered without the patient’s awareness.

Thomas (20) suggests that physicians who have confidence in the capability of their treatment and who convey confidence and empathy with the patient are more likely to promote a positive placebo response. This proposal may be supported by recent research in sport. In an ethnographic study, Howe (21) observed what he described as placebo effects associated with the ‘unsys- tematic’ treatment of injuries in a professional rugby club. Players were generally given treatments based upon what equipment was available at the time (ultrasound or interferential), largely irre- spective of what injury the player had sustained. Howe observed that the players appeared to be given different treatments until

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