Hope, expectation & the placebo

Hope has been attributed as the primary mechanism of change in traditional healing, and in psychotherapy.

Hope can be defined as the desire and expectation that the future will be better than the present.

Expectation may also play a role in the 'Hawthorne Effect' - this is the clinical improvements seen in patients simply due to the fact that they are being observed.  A patient who knows that they are being studied may expect a better therapeutic outcome because of the many examinations, the special attention and the trust in the new therapy under investigation.

Expectation of a future positive outcome may reduce anxiety and/or activate the neuronal networks of reward mechanisms (the reverse can be true). When given a placebo, if you expect a distressing symptom to  subside soon then you become less anxious (eg. as soon as I take pain relief medication for a headache I start to become less concerned about it even though I know it won't take effect for a while).