國家心智健康研究中心與Gulf Atlantic Group Incorporated公司資助該研究。DeWall醫師、Flaten醫師與 Charlton醫師皆宣告沒有相關財務關係。
Psychol Sci (付印中)。
Acetaminophen May Also Relieve Psychological Pain
By Janis C. Kelly
Medscape Medical News
December 30, 2009 — Opiates and other strong analgesics have long beenknown to numb psychological as well as physical pain, but newevidence suggests that even mild over-the-counter drugs likeacetaminophen may relieve psychological discomfort, such as the stressof social rejection.
A research team led by psychologist C. Nathan DeWall, PhD, from the University of Kentucky College of Arts and Sciences, Departmentof Psychology, Lexington, examined the overlap between neural andpsychological pain by randomly assigning healthy volunteers to 3 weeksof either daily acetaminophen or placebo, then comparing self-reportsof social pain.
In a second study, the researchers used functional magnetic resonanceimaging in an attempt to correlate changes in brain activity in regionsbelieved to be associated with responses to social rejection withsubjects' experiences of social pain.
"Theidea that a drug designed to alleviate physical pain should reduce thepain of social rejection seemed simple and straightforward based onwhat we know about neural overlap between social and physical painsystems. To my surprise, I couldn't find anyone who had ever testedthis idea," Dr. DeWall said.
He described "social pain" as "a painful affective response to aperceived threat to social belonging. Social rejection is one example of a socially painful event."
The research is due to be published in an upcoming edition of Psychological Science.
Hurt Feelings Measured
The first experiment included 62 healthy volunteers randomly assignedto 1000 mg/day of either acetaminophen or placebo. Each evening,participants used a version of the Hurt Feelings Scale to report howmuch social pain they experienced that day.
As expected, hurt feelings decreased significantly over time amongparticipants who took acetaminophen (P < .05), but they wereunchanged in the placebo group, the researchers report.
"These data provide some of the first evidence that reducing physicalpain can reduce the pain of social rejection. They add to ourunderstanding of how seemingly different types of painful experiencesare processed through the same neurobiological systems," Dr. DeWalltold Medscape Psychiatry.
In the second experiment, the acetaminophen dose was doubled to 2000mg/day in an attempt to compensate for the lower statistical powerassociated with the smaller groups (10 participants randomly assignedto acetaminophen, 15 participants randomly assigned to placebo).
After 3 weeks of taking the pills, the subjects participated in a computer game rigged to create feelings of social rejection.
Functional magnetic resonance imaging findings showed that theacetaminophen group had significantly less neural activity than theplacebo group during the game in brain regions associated with thedistress of social pain and with the affective component of physicalpain (the dorsal anterior cingulate cortex and anterior insula).
However, the acetaminophen and control groups "reported equal levels ofsocial distress in response to the exclusion episode," the researchersreport.
Potential to Reduce Violent Behavior?
Dr. DeWall said that despite the drug's lack of effect on theexperience of social distress, the researchers concluded thatacetaminophen reduced the pain of social rejection at the neural level.
The data "suggest that at least temporary mitigation of socialpain–related distress may be achieved by means of an over-the-counterpainkiller that is normally used for physical aches and pains."
The investigators further suggest that acetaminophen may preventviolent behavior, as "many studies have shown that being rejected cantrigger aggressive and antisocial behavior, which could lead to furthercomplications in social life.... If acetaminophen reduces the distressof rejection, the antisocial behavioral consequences of rejection maybe reduced as well."
"This research has the potential to change how scientists andlaypersons understand physical and social pain. Social pain, such aschronic loneliness, damages health as much as smoking and obesity. Wehope our findings can pave the way for interventions designed to reducethe pain of social rejection," said Dr. DeWall.
Kudos
Asked by Medscape Psychiatry to comment on the study, Bruce G. Charlton, MD, applauded the investigators' research efforts.
"It is particularly difficult to get research funding to study old,cheap, unpatented, over-the-counter drugs, so I congratulate theauthors on doing this," he said.
Dr. Charlton, who is editor-in-chief of Medical Hypotheses andprofessor of theoretical medicine at the University of Buckingham,United Kingdom, agreed that different sorts of pain are often related,so there is good reason to assume that acetaminophen or paracetamol maybenefit those who suffer any type of pain of unpleasant feelings,including some types of depression.
However, he noted that the same effect would likely apply to aspirin,nonsteroidal anti-inflammatory drugs, and opiates, "about which thereis more evidence," he said.
Alternative Interpretation
Magne Arve Flaten, MD, from the department of clinical research atUniversity Hospital of North Norway, Tromso, also commented on thestudy for Medscape Psychiatry. Dr. Flaten, who recently published astudy of cognitive and emotional factors in placebo analgesia, saidthat alternative interpretations of the data are possible.
"The authors seem to think that rejection induces 'social pain,' but itwould probably, in my view, be more correct to say that both pain andsocial rejection are associated with unpleasantness and other negativeemotions.
"Social pain is not pain as we ordinarily think of it, but it sharessome of the emotional aspects that pain has, and aspects that probablyother negative emotions also have," said Dr. Flaten.
He noted that the investigators' first experiment showed thatacetaminophen reduced "hurt feelings," but that the effects, althoughsignificant, "seem small." He suspects that the researchers' inabilityto replicate the psychological effect in the second experiment may havebeen a result of lack of power because of the small sample size.
"I do not think this research tells us anything about pain, since pain,in a normal sense of the word, was not investigated in theseexperiments. The research tells us that acetaminophen could reduce someof the negative emotional consequences of social rejection, which isvery interesting," Dr. Flaten said.
The study was funded by the National Institute of Mental Health and theGulf Atlantic Group Incorporated. Dr. DeWall, Dr. Flaten, and Dr.Charlton have disclosed no relevant financial relationships.
