***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: & NA ; Given the lack of objective physical measures for assessing fibromyalgia syndrome ( FS ) , the role of pain assessment is particularly important . The role of psychological factors is controversial among FS patients . This study was design ed to better underst and the relationship between pain behaviors and psychological variables . Specifically , this study ( 1 ) refined a pain behavior observation ( PBO ) methodology for use with FS patients , ( 2 ) determined whether stretching is a valid pain behavior,(3 ) assessed whether psychological variables including self‐efficacy and /or depression can predict pain behaviors after controlling for disease severity and age . The 73 FS subjects meeting the American College of Rheumatology classification system completed question naires measuring self‐efficacy , depression , and pain . Trained physicians conducted tender‐point examinations . Subjects were videotaped using a st and ardized procedure . Two trained raters independently coded all pain behaviors . Kappa coefficients and correlations among pain behaviors and self‐reported pain indicated that the PBO method was both reliable and valid . However , the newly defined pain behavior ‘ stretching ’ was found to be negatively associated with self‐reported pain . Hierarchical multiple regression ( MR ) analyses revealed that depression did not predict pain behavior over and above myalgic scores and age ; however , in 3 separate MR analyses , self‐efficacy for function , pain , and other symptoms each predicted pain behavior over and above myalgic scores and age . This study indicated that the original  pain behavior scoring methodology is appropriate for use with the FS population and should not be modified to include the pain behavior ‘ stretching ’ . Self‐efficacy was related to pain behavior while depression was not among this FS sample & NA ; It has been shown that a person 's mood can influence  pain tolerance .  Films have been used as a means of inducing a desired mood . The effect on pain perception of film type and film length to induce mood was investigated . Previous research with brief humorous films had not indicated any unique advantage of humor over distraction approaches . Other recent research had indicated that after exposure to film stimulation there is a need to wait approximately 40 min before physiological changes can be obtained . Thus , the present study varied both film type and length and introduced a 30‐min waiting period following the mood induction via film prior to exposure to cold‐pressor pain .  Two hundred subjects in nine different groups participated in the study . Three types of films were used : ( 1 ) humorous , ( 2 ) holocaust , ( 3 ) neutral . Three lengths of each type were also used : 15 min , 30 min , and 45 min . In addition , a tenth no‐film group served as a control for the effects of a film . Each subject was given a baseline trial of cold‐pressor pain , a trial immediately following the film and a trial 30 min later . Results indicated an advantage in increased pain tolerance for the humorous film and an increased pain tolerance for the longer film regardless of type only after the 30‐min waiting period . Results were discussed from a pain theoretical perspective with emphasis placed on returning to psychological manipulations of the sensory aspects of pain and not just the cognitive/emotional/motivational dimensions OBJECTIVE To evaluate the Stress Process Model proposed by Pearlin and colleagues by examining the role of personal and social re sources in mediating the relationship between the rheumatoid arthritis ( RA ) related stressors of functional disability , pain , and flares , and the outcome of depressive symptoms . METHODS Data are from 285 patients who participated in a study of the natural history of RA , comorbidity and depression . Measures include the Center for Epidemiologic Studies -Depression ( CES-D ) scale , the Arthritis Impact Measurement Scale Functioning and Pain scales , the Lubben Social Network scale , and items indicating sociodemographic status , health status and personal re sources .  A series of hierarchical regression analyses with multiplicative interaction terms were conducted . RESULTS Substantial consistency between the Stress Process Model and relationships observed in the data was demonstrated . CONCLUSION Although no cl aim is made to having demonstrated that the observed relationships are causal , the fact that the data are consistent with the model invites a prospect i ve analysis in which the ordering of the variables over time can be established unambiguously . Because of the implication s of the Stress Process Model for the design of psychosocial interventions , such a test is especially important Although patients with chronic pain are often psychologically distressed , it has been difficult to determine whether this distress is an antecedent of chronic pain or whether it is caused by the experience of living with chronic pain . The aim of this investigation was to develop a method that would allow individuals who are at risk for the development of chronic pain to be studied before their pain has become chronic . Patients with acute herpes zoster were assessed with demographic , medical , pain , and psychosocial measures . Pain  was assessed in follow-up interviews at 6 weeks and 3 , 5 , 8 , and 12 months after these initial assessment s. There were no significant differences between patients who developed short-term herpes zoster pain and patients who did not develop short-term pain for any of the measures at the initial assessment , except for one measure of pain intensity . Patients who developed chronic herpes zoster pain , however , had significantly greater pain intensity , higher state and trait anxiety , greater depression , lower life satisfaction , and greater disease conviction at the initial assessment than patients who did not develop chronic pain . In discriminant analyses , disease conviction , pain intensity , and state anxiety each made a unique contribution to discriminating patients who did and who did not develop chronic pain .  This study demonstrates the feasibility of investigating psychosocial antecedents of the development of chronic pain by prospect ively examining the longitudinal course of herpes zoster & NA ; This report examined first onset rates of 5 common pain symptoms and assessed , on a prospect i ve basis , whether depressive symptoms at baseline were associated with onset risks . Adult Health Maintenance Organization ( HMO ) enrollees ( n = 1016 ) were interviewed in 1986 about their history of each of 5 pain conditions ( back pain , severe headache , chest pain , abdominal pain and temporom and ibular disorder ( TMD ) pain ) . Three years later , this sample was re‐interviewed ( n = 803 ) to measure site‐specific first onset rates . The Symptom Checklist 90‐Revised ( SCL‐90‐R ) Depression scale  was administered at baseline and at 3 year follow‐up . Over the three year follow‐up interval , rates of first onset were : 17.7 % for back pain ; 4.2 % for severe headache ; 3.0 % for chest pain ; 3.1 % for abdominal pain ; and 6.5 % for TMD pain . Onset rates of persistent pain and of chronic pain dysfunction were substantially lower , but over 1 % experienced onset of chronic pain dysfunction for back pain and for headache . There were not significant differences in onset rates of back pain , abdominal pain or TMD pain by severity or chronicity of depressive symptoms . Relative to the non‐depressed , persons with moderate‐to‐severe depressive symptoms were more likely to develop headache and chest pain ( adjusted odds ratios of 1.7 to 5.0 ) . For headache and chest pain , onset risks were highest among the chronically depressed . After adjusting for age , gender , education and depression severity , persons with a pain condition at baseline were more likely to report first onset of a new pain condition over the follow‐up period ( adjusted odds ratios of 2.1 for back pain , 4.3 for headache , 1.4 for chest pain , 6.3 for abdominal pain and 3.7 for TMD pain ) . Thus , presence of a pain condition was a more consistent predictor of subsequent risks of developing a new pain condition than was the severity or chronicity of depressive symptoms . Possible explanations for this relationship are considered The relationship between pain perception and emotional states is well known . However , the nature of this relationship and how different emotional states affect sensory and cognitive dimensions of pain remains uncertain . Results from experimental investigations are often contradictory , which may be due to method ological difficulties in inducing pain and monitoring physiological responses . In addition , most studies have focused on a single emotion , and data on the relative effects of different emotional states are lacking . In the present study we attempted to eliminate some of these method ological problems . Laser evoked potentials were used as a quantitative correlate to pain perception and were measured in 12 highly hypnotically susceptible subjects during seven conditions : ( a ) a prehypnotic baseline condition ; ( b ) a neutral hypnotic control condition ; ( c-e ) hypnotically recalled anger , fear , and depression in r  and omized  order ; ( f ) a hypnotically recalled happy condition , and ( g ) a posthypnotic awake control condition . The pain evoked potentials were significantly decreased in the angry condition and significantly increased in the depressed condition compared with baseline . No differences could be detected for either the happy or the fear-related condition compared with the baseline or neutral hypnotic condition . A significant positive correlation between the subjective intensity of depression and the increase in evoked potentials was found , but none for the other three emotions . The results support earlier findings that clinical depression is related to increased pain perception , and findings that the expression of anger can inhibit the experience of pain . ( ABSTRACT TRUNCATED AT 250 WORDS & NA ; In a homogeneous sample of 20 healthy male students , the analgesic effects of the tricyclic antidepressant imipramine ( 100 mg ) were compared to those of the narcotic meperidine ( 150 mg ) and a further tricyclic compound with assumed analgesic properties ( fluradoline , 450 mg ) . Drugs were orally administered , using a placebo controlled , double‐blind repeated measures Latin Square design . Phasic pain was induced by intracutaneous electrical shocks with r and om intensities and interstimulus intervals . Each stimulus block consisted of 80 stimuli and lasted for 20 min . Pain estimates , somatosensory evoked cerebral potentials ( SSEPs ) and power spectral density of the electroencephalogram ( EEG ) were measured under each drug condition . Under placebo , pain ratings and SSEP amplitudes were constant within the entire session lasting for approximately 4 h.  Meperidine analgesia was evident within 30 min of drug application , reaching a maximum after about 90 min . Imipramine produced a comparable degree of pain reduction , however , with a delay of 2 h. Under both drugs , the decrease in pain ratings was accompanied by decreased amplitudes of the late components of the SSEP , as well as by a reduction in alpha activity and an enhancement of slow EEG waves . Effects of fluradoline on experimental pain could not be affirmed . These findings are discussed in terms of pain relief and decrease in vigilance 
    Output:
    
Depressed subjects are less likely to perceive a sensory stimulus as being painful compared with nondepressed controls .
The influence of depression on attention to the pain stimulus may account for this effect .