One of the new research on brain says “Placebo response,
pain experience occur at nonconscious level”
With the discovery that the unconscious mind plays a key
role in the placebo effect, researchers have identified a novel mechanism that
helps explain the power of placebos and nocebos.
Described in the September 10 on-line issue of the
Proceedings of the National Academy of Sciences (PNAS), the new findings
demonstrate that the placebo effect can be activated outside of conscious
awareness, and provide an explanation for how patients can show clinical
improvement even when they receive treatments devoid of active ingredients or
of known therapeutic efficacy. "In this study, we used a novel
experimental design and found that placebo and nocebo [negative placebo]
effects rely on brain mechanisms that are not dependent on cognitive
awareness," explains first author Karin Jensen, PhD, of the Department of
Psychiatry and the Martinos Center for Biomedical Imaging at Massachusetts General
Hospital (MGH) and the Program in Placebo Studies (PiPS) at Beth Israel
Deaconess Medical Center/Harvard Medical School. "A person can have a
placebo or nocebo response even if he or she is unaware of any suggestion of
improvement or anticipation of getting worse." It has long been believed
that placebo responses are related to conscious beliefs or thoughts and that
when given an inert pill or therapy, patients get better because they have the
expectation that they will get better, or in the case of nocebos, get worse
because they anticipate that they will get worse. However, more recently,
scientists have recognized that humans learn to expect either reward or threat
quickly and automatically without needing to consciously register the idea in
their brains.
As the authors
write, neuroimaging studies of the human brain have suggested that certain
structures, such as the striatum and the amygdala, can process incoming stimuli
before they reach conscious awareness, and, as a result, may mediate non-conscious
effects on human cognition and behavior. The scientists set out to determine
whether placebo and nocebo responses might be activated outside of a person's
conscious awareness, even if he or she has no expectation of either improving
or declining. Jensen, together with the study's senior author Jian Kong, MD,
also of MGH and the PiPS, studied 40 healthy volunteers (24 female; 16 male,
median age 23).
Two experiments
were conducted: In the first, researchers administered heat stimulation to
participants' arms while simultaneously showing them images of male human faces
on a computer screen. The first face was associated with low pain stimulations
and the second image with high pain. Patients were then asked to rate their
experience of pain on a scale of 0 to 100, 0 being no pain and 100 being the
worst imaginable pain, but without the patient's knowledge that all heat
stimulations would have the same moderate heat intensity. As predicted, the
pain ratings correlated with the previously learned associations, with a pain
rating of 19 when the subjects saw the low pain face while the high pain face
resulted in subjects' mean reports of 53 on the pain scale (nocebo effect).
Then, in the second experiment, the participants were
administered the same levels of thermal heat stimulation. Once again, the
facial images were projected on the computer screen – but this time, they
flashed by so quickly that subjects could not consciously recognize them. The
participants once again rated their pain, and despite a lack of consciously
recognizable cues, the participants reported a mean pain rating of 25 in
response to the low pain face (placebo effect) and a mean pain rating of 44 in
response to the high pain face (nocebo response) even though they did not
consciously recognize the faces on the screen. "Such a mechanism would
generally be expected to be more automatic and fundamental to our behavior
compared to deliberate judgments and expectations," explains Kong.
"Most important, this study provides a unique model
that allows us to further investigate placebo and nocebo mechanisms by using
tools such as neuroimaging." As PiPS Director and study coauthor Ted
Kaptchuk notes, "It's not what patients think will happen [that influences
outcomes] it's what the nonconscious mind anticipates despite any conscious
thoughts. This mechanism is automatic, fast and powerful, and does not depend
on deliberation and judgment. These findings open an entirely new door towards
understanding placebos and the ritual of medicine."
Psychtronics.com gives the only interesting topics of psychology and you need not to be a professional to understand the articles in the psychtronics. They are easy to understand to every one and it is mainly for the college students and Psychiatrists.
Like us in FB to get Updates: www.facebook.com/psychtronics
Post a Comment