(see Chapter 3) will be altered because patients believe they have an important new
resource, namely, a treatment that will cure or alleviate adverse symptoms. Anxiety
reduction is known to have physiological effects. For example, it is likely to affect
endocrine functioning, reducing levels of cortisol and adrenalin in the bloodstream.
This, in turn, may have positive effects on blood pressure and immune functioning
(see Chapter 2) as well as on cognitive functioning (e.g. memory). Anxiety reduction
is also associated with reduced pain because downward neural pathways from the brain
can cut off or ‘gate’ incoming pain signals from peripheral nerves (Melzack and Wall,
1965). Thus a stress reduction explanation based on expectations of treatment efficacy
provides a powerful explanation of some placebo effects. This explanation corresponds
to Little et al.’s observation that patients reported fewer symptoms after consultations
in which doctors adopted a positive and definite approach including providing
guidance on when the problem would be resolved. Moreover, an expectation-based
explanation could account for the direct effects of adherence because the more con -
sciously one adheres to the apparently effective treatment the stronger one’s expectation
of relief or recovery should be. Nonetheless, this explanation does not account for
all placebo effects. For example, objectively assessed bronchodilation placebo effect
findings observed by Butler and Steptoe (1986) could not be explained by changes in
expectations or anxiety.
Explaining placebo effects: classical conditioning
Classical conditioning theory may account for some placebo effects. In this model the
‘real’ drug is the unconditioned stimulus and beneficial physiological changes are
the unconditioned response. Similarity of administration of the placebo treatment (e.g.
context, nature of treatment, etc.) leads to an association between the placebo
treatment (the conditioned stimulus) and the unconditional stimulus. Such effects
have been observed in people and animals. For example, Benedetti, Pollo and Colloca
(2007) examined the effect of repeated administrations of injected morphine during
athletes’ training sessions on placebo response. They found that athletes who had
had morphine injections during training and who then received a saline injection
(which they thought was morphine) showed greater pain endurance and physical
performance during competition. This has interesting implications for drug testing in
sport because it suggests that after appropriate drug conditioning it may be enough for
an athlete to believe she is taking a performance-enhancing drug in order to enhance
performance.
The placebo effect literature strongly emphasizes how important it is to provide
patients with expectations of recovery (where it is reasonable and ethical to do so) and
to encourage commitment to adherence. The psychological consequences of these
processes may greatly enhance the pharmacological processes generated by available
drugs. Practitioners able to harness and deliver the psychological and physiological
effects evident in placebo responding will maximize the health impact of interventions.
This was confirmed by a review of 19 trials. In this review Di Blasi et al.(2000)
concluded that various contextual factors affected treatment effectiveness and that, in
particular, there was evidence suggesting that cognitive care (that is managing
expectations positively) and emotional care (communicating concern for the patient’s
problems) maximizes treatment effectiveness. Thus to optimize their effectiveness
246 RELATING TO PATIENTS