title: Adherence, expectations and the placebo response: why is good adherence to an inert treatment beneficial?
abstract: OBJECTIVE
  The current study sought to better understand why good adherence to a placebo treatment has been reliably associated with health benefits. We proposed a model where initial expectations shape adherence, which then influences subsequent expectations that affect placebo response.
  
  
  METHODS
  Seventy-two participants were told that they were enrolling in a study of physical activity and memory, and were asked to increase their physical activity by 35% for two weeks (placebo treatment).
  
  
  METHODS
  Adherence to this physical activity target was measured by pedometer. Expectations and short-term memory (free recall) were assessed before and after physical activity.
  
  
  RESULTS
  Initial expectations predicted adherence to physical activity (r = .27, p < .03), but adherence did not predict subsequent expectations (r = .06, p = .60). Testing a multi-step meditational model revealed that initial expectations predicted better memory even after controlling for adherence, subsequent expectations, baseline memory and gender (c' = 1.10, 95% CI = .46-1.74). Stronger expectations for memory improvement predicted better memory performance, but adherence and later expectations did not mediate this association.
  
  
  CONCLUSIONS
  Good adherence to a placebo may reflect strong treatment expectations which may convey benefits by enhancing the non-specific effects of treatment.
authors: a Department of Psychology , Furman University , Greenville , SC , USA.
authors: Cinnamon
authors: C
authors: Stetler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001294:Attitude to Health; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation; D009043:Motor Activity; D010349:Patient Compliance / Q000706:statistics & numerical data*; D015990:Placebo Effect; D011446:Prospective Studies; D016896:Treatment Outcome; D055815:Young Adult
references: Health Educ Monogr. 1978 Winter;6(4):394-405
references: 299611
references: Psychosom Med. 1993 Mar-Apr;55(2):149-54
references: 8475229
references: J Phys Act Health. 2010 Nov;7(6):706-17
references: 21088300
references: Memory. 2011 Aug;19(6):606-12
references: 21919588
references: Eval Health Prof. 2002 Dec;25(4):436-64
references: 12449086
references: J Gen Intern Med. 2011 May;26(5):546-50
references: 21203857
references: Psychother Psychosom. 2009;78(3):167-71
references: 19270472
references: Med Care. 2004 Mar;42(3):200-9
references: 15076819
references: J Abnorm Psychol. 1969 Oct;74(5):568-73
references: 5349398
references: Health Psychol. 1995 Jan;14(1):74-9
references: 7737077
references: Contemp Clin Trials. 2012 May;33(3):492-8
references: 22265975
references: Arch Gen Psychiatry. 2004 Apr;61(4):412-20
references: 15066900
references: J Clin Exp Neuropsychol. 2008 Jan;30(1):7-17
references: 18165936
references: Aust N Z J Psychiatry. 2005 Jul;39(7):583-90
references: 15996139
references: J Consult Clin Psychol. 2005 Apr;73(2):350-3
references: 15796644
references: Med Care. 2011 May;49(5):427-35
references: 21422960
references: J Gen Intern Med. 2010 Dec;25(12):1275-81
references: 20706875
references: Psychol Sci. 2003 Mar;14(2):125-30
references: 12661673
references: Eur Respir J. 2008 Sep;32(3):710-7
references: 18417510
references: BMJ. 2006 Jul 1;333(7557):15
references: 16790458
references: Prev Med. 2005 Mar;40(3):293-8
references: 15533542
references: J Psychosom Res. 1999 Dec;47(6):555-67
references: 10661603
references: Psychol Bull. 2004 Mar;130(2):324-40
references: 14979775
references: J Allergy Clin Immunol. 2011 Feb;127(2):406-11
references: 21281871
references: J Psychosom Res. 2008 Jan;64(1):47-54
references: 18157999
references: Pharmacoeconomics. 2010;28(12):1097-107
references: 21080735
references: JAMA. 2007 Nov 21;298(19):2296-304
references: 18029834
references: Circulation. 2009 Apr 21;119(15):2051-7
references: 19349320
references: Eval Health Prof. 2005 Mar;28(1):9-26
references: 15677384
references: Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):3017-22
references: 21282661
references: J Neurosci. 2003 May 15;23(10):4315-23
references: 12764120
references: Am J Psychol. 2007 Summer;120(2):287-301
references: 17650922
references: Lancet. 2005 Dec 10;366(9502):2005-11
references: 16338449
references: Am J Epidemiol. 2007 Aug 1;166(3):348-54
references: 17504779
references: Psychopharmacology (Berl). 1992;106(2):209-14
references: 1549648