Are Patients With Schizophrenia Insensitive to Pain? A Reconsideration of the Question

Inflammation and the two-hit hypothesis of schizophrenia

The high societal and individual cost of schizophrenia necessitates finding better, more effective treatment, diagnosis, and prevention strategies. One of the obstacles in this endeavor is the diverse set of etiologies that comprises schizophrenia. A substantial body of evidence has grown over the last few decades to suggest that schizophrenia is a heterogeneous syndrome with overlapping symptoms and etiologies. At the same time, an increasing number of clinical, epidemiological, and experimental studies have shown links between schizophrenia and inflammatory conditions. In this review, we analyze the literature on inflammation and schizophrenia, with a particular focus on comorbidity, biomarkers, and environmental insults. We then identify several mechanisms by which inflammation could influence the development of schizophrenia via the two-hit hypothesis. Lastly, we note the relevance of these findings to clinical applications in the diagnosis, prevention, and treatment of schizophrenia.

Clinical pain in schizophrenia: a systematic review

Studies about clinical pain in schizophrenia are rare. Conclusions on pain sensitivity in people with schizophrenia are primarily based on experimental pain studies. This review attempts to assess clinical pain, that is, everyday pain without experimental manipulation, in people with schizophrenia. PubMed, PsycINFO, Embase.com, and Cochrane were searched with terms related to schizophrenia and pain. Methodological quality was assessed with the Mixed Methods Appraisal Tool. Fourteen studies were included. Persons with schizophrenia appear to have a diminished prevalence of pain, as well as a lower intensity of pain when compared to persons with other psychiatric diseases. When compared to healthy controls, both prevalence and intensity of pain appear to be diminished for persons with schizophrenia. However, it was found that this effect only applies to pain with an apparent medical cause, such as headache after lumbar puncture. For less severe situations, prevalence and intensity of pain appears to be comparable between people with schizophrenia and controls. Possible underlying mechanisms are discussed. Knowledge about pain in schizophrenia is important for adequate pain treatment in clinical practice.

PERSPECTIVE

This review presents a valuable insight into clinical pain in people with schizophrenia.

Chronic pain and quality of life in schizophrenic patients

OBJECTIVE

To identify the prevalence and characteristics of chronic pain in schizophrenic patients and to compare the quality of life in patients with and without chronic pain.

METHODS

Crossover design with a probablistic sample of 205 adult schizophrenic outpatients (80% paranoid schizophrenia). Socio-demographic, psychiatric disorder, pain and quality of life (WHOQOL- brief) data were collected between June and September 2008.

RESULTS

Mean age was 37 years, 65% were men, and the mean time spent in school was 9 years; 87% were single, 65% lived with parents and 25% had a job. Among patients with chronic pain, 70% did not receive treatment for pain. Regarding quality of life, patients with pain had more physical disabilities compared to those without pain (p < .001). There were no differences in other domains. Comparisons between patients with and without pain did not show any differences in how much they felt their mental health problems disabled them.

CONCLUSION

Chronic pain was common in schizophrenic patients (similar to the general population of a similar age) and decreased their quality of life. It is necessary to pay more attention to this co-morbidity.

Oversight of constipation in inpatients with schizophrenia: a cross-sectional study

OBJECTIVE

Constipation is often overlooked in patients with schizophrenia. We examined their awareness of constipation and whether they reported it to their psychiatrists.

METHOD

Five hundred three inpatients with schizophrenia (International Classification of Diseases, 10th Revision) were interviewed about their recent bowel movements and evaluated for the diagnostic criteria for functional constipation. If constipation was present, patients were asked if they were aware of it and had reported it to their psychiatrists in charge. Additionally, their global psychopathology and functioning were assessed using the Clinical Global Impression-Schizophrenia (CGI-SCH) and the Global Assessment of Functioning (GAF), respectively.

RESULTS

The criteria for constipation were met by 184 patients (36.6%); of these patients, only 56.0% (103/184) were aware of it. Moreover, only 34 of the constipated patients (18.5%) reported its presence to their psychiatrists. No significant differences were found in the CGI-SCH overall severity or subscale scores or in the GAF scores between those patients who reported and those who failed to report constipation.

CONCLUSIONS

The present study demonstrated that constipation was neither recognized nor reported to psychiatrists by a significant percentage of the patients. These findings underscore the importance of greater vigilance and active evaluation of constipation in patients with schizophrenia for appropriate clinical management.

[Cesarean section and sismotherapy in a severe psychotic parturient: A case report]

Psychiatric disorders may complicate the pregnancy and is one of the causes of maternal and fetal morbidity. We report the case of a patient with severe decompensated schizophrenia during her pregnancy that required prolonged hospitalization in psychiatric ward. The psychiatric status of the patient required the realization of a caesarean section at 36 weeks of amenorrhea. In our case, we decided to perform this cesarean section under general anaesthesia, since regional anaesthesia was not feasible in this patient in a state of uncontrolled agitation. Moreover, general anaesthesia permitted to combine cesarean section with a first session of electroconvulsive therapy, which had been declined during pregnancy. Given the huge amount of antipsychotic agents administered to the patient, we also studied their transplacental transfer and found a very high loxapine concentration in the fetus. Finally, this case raised several important ethical issues related to the management of the mother and her fetus in case of severe psychiatric disorders.

Pain conditions among veterans with schizophrenia or bipolar disorder

OBJECTIVE

The purpose of this study was to assess the rates of chronic, noncancer pain conditions in patients with schizophrenia or bipolar disorder within the Veterans Health Administration (VHA) System.

METHOD

This cross-sectional study used administrative data extracted from VHA treatment records of all individuals receiving VHA services in fiscal year 2008 (N=5,195,551). The associations between severe psychiatric disorders (schizophrenia and bipolar disorder) and chronic pain (arthritis, back pain, chronic pain, migraine, headache, psychogenic and neuropathic) were evaluated using a series of logistic regression analyses.

RESULTS

Veterans with schizophrenia [odds ratio (OR)=1.21] and bipolar disorder (OR=2.17) were significantly more likely to have chronic pain overall relative to veterans without these psychiatric conditions. These associations were slightly lower than for the association between depression and pain in this sample (OR=2.61). The highest associations between specific psychiatric diagnosis and pain condition were found with chronic pain, headache and psychogenic pain.

CONCLUSIONS

Noncancer pain conditions occur in elevated rates among patients with schizophrenia and bipolar disorder. Future research could further examine possible barriers to adequate pain treatment among people with serious mental illness, as well as the extent to which chronic pain might impact mental health recovery.

Surgical adverse outcomes in patients with schizophrenia: a population-based study

OBJECTIVE

To validate the global features of postoperative adverse outcomes for surgical patients with schizophrenia.

BACKGROUND

Patients with schizophrenia were known to have a higher risk of complications during hospitalization. Quality of care has become the key factor in reducing their potential mortality afterwards.

METHODS

We present a population-based study of 8967 schizophrenic patients receiving major surgery from the Taiwan National Health Insurance Research Database within the years 2004 and 2007 compared with 35,868 surgical patients without mental disorders. Eight major postoperative complications and mortality after complications were evaluated among schizophrenic patients with different severity.

RESULTS

Schizophrenic patients had significantly higher risk for postoperative complications, including acute renal failure, pneumonia, bleeding, septicemia, stroke, and 30-day postoperative mortality (adjusted OR = 2.70; 95% CI: 2.08-3.49), than surgical patients without mental disorders. Among surgical patients with 1 to 2, 3 to 18, 19 to 48, and more than 49 schizophrenia-related outpatient visits within 24-month period preoperatively, the adjusted ORs of 30-day mortality ranged from 1.95 (95% CI: 1.25-3.02) to 3.97 (95% CI: 2.66-5.92) in a frequency-dependent pattern when compared with controls. When compared with surgical patients with schizophrenia-related outpatient services only, OR of 30-day postoperative mortality increased from 2.54 (95% CI: 1.93-3.34) to 3.69 (95% CI: 2.25-6.03) in surgical patients with preoperative hospitalization or emergency visit because of schizophrenia.

CONCLUSIONS

Surgical patients with schizophrenia showed significantly higher postoperative adverse outcome rates with risk of 30-day mortality nearly threefold when compared with patients without mental disorders. Our findings suggest the urgency revising the protocol of postoperative care for this specific population.

Alteration of pain recognition in schizophrenia

BACKGROUND

Schizophrenia patients display impaired recognition of their own emotions and those of others and deficits in several domains of empathy. The first-person experience of pain and observing others in pain normally trigger strong emotional mechanisms. We therefore hypothesized that schizophrenia patients would display impaired recognition and categorization of both their own pain and the pain of others.

METHODS

We studied 29 patients (18 men/11 women; 36 ± 13 years old) with paranoid schizophrenia-spectrum disorder and 27 healthy volunteers (20 men/7 women; 31 ± 9 years old) matched for age, gender, IQ and socio-cultural level. We assessed symptom severity and theory of mind. The participants' ability to detect and categorize pain in others was assessed with the sensitivity to expressions of pain (STEP) test, which is based on facial expressions, and another dynamic test involving a series of video sequences showing various pain-inducing events. The ability of patients to evaluate their own pain was assessed with the situational pain questionnaire (SPQ), which includes a series of questions assessing how one would expect to feel in different imaginary situations. Empathic tendencies were assessed with the interpersonal reactivity index.

RESULTS

Patients and controls differed significantly in STEP, pain video and SPQ scores. By contrast with control subjects, the patients' pain judgements were not correlated with their affective or cognitive empathic capacities.

CONCLUSIONS

Schizophrenic patients have a deficit of the identification and categorization of pain both in themselves and in others.

Pain and analgesia: the value of salience circuits

Evaluating external and internal stimuli is critical to survival. Potentially tissue-damaging conditions generate sensory experiences that the organism must respond to in an appropriate, adaptive manner (e.g., withdrawal from the noxious stimulus, if possible, or seeking relief from pain and discomfort). The importance we assign to a signal generated by a noxious state, its salience, reflects our belief as to how likely the underlying situation is to impact our chance of survival. Importantly, it has been hypothesized that aberrant functioning of the brain circuits which assign salience values to stimuli may contribute to chronic pain. We describe examples of this phenomenon, including 'feeling pain' in the absence of a painful stimulus, reporting minimal pain in the setting of major trauma, having an 'analgesic' response in the absence of an active treatment, or reporting no pain relief after administration of a potent analgesic medication, which may provide critical insights into the role that salience circuits play in contributing to numerous conditions characterized by persistent pain. Collectively, a refined understanding of abnormal activity or connectivity of elements within the salience network may allow us to more effectively target interventions to relevant components of this network in patients with chronic pain.

Lack of insula reactivity to aversive stimuli in schizophrenia

Patients with schizophrenia may have altered pain perception, as suggested by clinical reports of pain insensitivity, and recent neuroimaging findings. Here, we examined neural responses to an aversive electrical stimulus and the immediate anticipation of such a stimulus using fMRI and a classical conditioning paradigm, which involved pairing an electrical shock with a neutral photograph. Fifteen men with schizophrenia and 13 healthy men, matched for demographic characteristics, electrical stimulation level and scan movement, were studied. The shock induced robust responses in midbrain, thalamus, cingulate gyrus, insula and somatosensory cortex in both groups. However, compared to controls, the schizophrenic patients displayed significantly lower activation of the middle insula (p(FWE)=0.002, T=5.72, cluster size=24 voxels). Moreover, the lack of insula reactivity in the schizophrenia group was predicted by the magnitude of positive symptoms (r=-0.46, p=0.04). In contrast, there were no significant differences between the two groups in the magnitude of neural responses during anticipation of the shock. These findings provide support for the existence of a basic deficit in interoceptive perception in schizophrenia, which could play a role in the generation and/or maintenance of psychotic states.

Attitudes toward menstruation in females with schizophrenia or schizoaffective disorders in Taiwan

OBJECTIVE

The aims of this cross-sectional, case-controlled, observational study were to examine attitudes toward menstruation in female patients with schizophrenia or schizoaffective disorder and in a control group, and to explore the associations between attitudes toward menstruation and psychopathology, menstrual regularity during antipsychotic treatment, and menstrual distress symptoms.

METHODS

Fifty-eight patients treated with anti-psychotic medications for at least the previous 6 months were placed in irregular (irregular menstrual cycle) (n = 31) and regular (regular menstrual cycle) (n = 27) groups. Sixty-two, age-matched, healthy female participants with regular menstrual cycles were enrolled as a control group. Psychopathology was assessed by psychiatrists using the Positive and Negative Syndrome Scale (PANSS). The Menstrual Attitude Questionnaire (MAQ) was used to assess attitudes toward menstruation, and symptom checklists based on the Moos Menstruation Distress Questionnaire (MMDQ) were used to assess menstrual distress symptoms.

RESULTS

Patients with psychotic disorders (both irregular and regular groups) had more negative attitudes toward menstruation than the control group. In the Schizophrenia group, there was no association between the severity of psychotic symptoms and their influence on attitudes toward menstruation. Moreover, regular menstrual cycles during antipsychotic treatment and fewer menstrual distress symptoms were the two main predictors for more positive attitudes toward menstruation in the patient group.

CONCLUSION

This is one of the first studies to explore the relationship between psychotic symptoms and attitudes toward menstruation. The findings provide more support for the assumption that attitudes toward menstruation are derived from a woman's perception of her bodily experience rather than a psychiatric disorder.

Injury risk and severity in a sample of Maryland residents with serious mental illness

OBJECTIVE

Adults with serious mental illness experience premature mortality and heightened risk for medical disease, but little is known about the burden of injuries in this population. The objective of this study was to describe injury incidence among persons with serious mental illness.

METHODS

We conducted a retrospective cohort study of 6234 Maryl and Medicaid recipients with serious mental illness from 1994-2001. Injuries were classified using the Barell Matrix. Relative risks were calculated to compare injury rates among the study cohort with injury rates in the United States population. Cox proportional hazards modeling with time dependent covariates was used to assess factors related to risk of injury and injury-related death.

RESULTS

Forty-three percent of the Maryland Medicaid cohort had any injury diagnosis. Of the 7298 injuries incurred, the most common categories were systemic injuries due to poisoning (10.4%), open wounds to the head/face (8.9%), and superficial injuries, fractures, and sprains of the extremities (8.6%, 8.5%, and 8.4%, respectively). Injury incidence was 80% higher and risk for fatal injury was more than four and a half times higher among the cohort with serious mental illness compared to the general population. Alcohol and drug abuse were associated with both risk of injury and risk of injury-related death with hazard ratios of 1.87 and 4.76 at the p<0.05 significance level, respectively.

CONCLUSIONS

The superficial, minor nature of the majority of injuries is consistent with acts of minor victimization and violence or falls. High risk of fatal and non-fatal injury among this group indicates need for increased injury prevention efforts targeting persons with serious mental illness and their caregivers.

When patients do not hurt: silent acute abdomen in a patient with schizophrenia

The phenomenon of pain insensitivity in schizophrenia and other psychotic disorders has been described since the early 20th century. Medical conditions often present atypically in the seriously mentally ill patient. Emergency physicians, primary care practitioners, surgeons and psychiatrists must maintain a high index of suspicion for acute abdomen in seriously mentally ill patients who may exhibit a diminished or absent perception of pain. The authors present a case of an atypical presentation of acute abdomen in a patient with schizophrenia.

Experimental pain hypersensitivity in schizophrenic patients

OBJECTIVE

Whether schizophrenic patients are hypoalgesic or feel pain in the same manner as unaffected individuals can affect the primary care of schizophrenic patients, which often involves an assessment of pain severity made by a medical provider. This study was developed to explore the pain sensitivity of schizophrenics under conditions similar to those of a medical examination that included investigating for sites of pain.

METHODS

We developed 2 experimental models of pain induction using either pressure or ischemia and used them with 35 schizophrenic patients and 35 controls to record: (1) the stimulus intensity required to induce moderate pain; and (2) the pain intensity induced by a predetermined level of pressure. Clinical data were also collected for the schizophrenic group.

RESULTS

Schizophrenic patients needed less pressure (P=0.006) and a shorter duration of ischemia (P<0.001) than controls to record moderate pain, and they felt more pain from a fixed pressure stimulus (P<0.001). Pain histories for the previous 6 months and the heart rate variations that occurred during the tests did not differ between the groups. Pain responses were unrelated to the clinical characteristics of the schizophrenic patients, although hallucination production correlated with the pain felt during the fixed pressure test.

DISCUSSION

Under these conditions, schizophrenic patients were hypersensitive to pain induction compared with normal individuals. The hypoalgesia typically associated with schizophrenic patients may correspond to fewer than normal reports of pain, rather than to impaired sensations of pain. This should be taken into account during routine medical practice.

Lingual abscess in a psychiatric patient: a case report

We present a 46-year-old psychiatric patient presenting with a lingual abscess. This paper covers the epidemiology, clinical features, diagnosis, and differential diagnosis with a view to assisting emergency physicians in the timely recognition and management of this rare but potentially life-threatening condition.

Sensitivity to expressions of pain in schizophrenia patients

Patients with schizophrenia tend to neglect their own pain and are known to have impairments in the processing of facial expressions. However, the sensitivity to dynamic expressions of pain has not been studied in these patients. Our goal was to test this ability in schizophrenia and to probe the underlying cognitive processes. We hypothesized that patients would have a reduced sensitivity to expressions of pain and that this impairment would correlate with deficits in attention, working memory, basic emotions recognition and with positive symptoms. We applied a battery of tests composed of the Comprehensive Affect Testing System (CATS), Sensitivity to Expressions of Pain (STEP), Toulouse-Pierón, Stroop and Digit Span tests to two groups of individuals, 27 patients with the diagnosis of schizophrenia and 27 healthy volunteers, matched on age, education and gender. Symptoms were assessed using Brief Psychiatric Rating Scale. The sensitivity to expressions of pain was found to be impaired in schizophrenia and a bias to attribute lower pain intensities may be present at some discrimination levels. STEP performance was correlated with working memory but not with Affect Naming or attention. These findings may contribute to the improvement of cognitive remediation strategies.

Pain Perception in Emergency Department Patients with and without Headache

Objectives

Adequate pain management of emergency department (ED) patients is an important clinical goal. Pain perception in ED patients with headache has been reported to differ from that of other patients with pain. If this were true in our setting, we might interpret pain scores and response to analgesics differently. We compared pain perception in ED patients without pain, patients with headache, and patients with non-headache pain who had blood pressure (BP) measurement and intravenous (IV) cannulation for any reason.

Methods

The study design was approved by our hospital's Ethics Committee. The patients were asked to describe their pain while undergoing BP measurement and IV cannulation with a 0 through 10 (11-point) numerical rating scale. Pain scores were analysed according to the patient's group: no pain, headache pain, or non-headache pain.

Results

For the 278 participating patients (95 patients without pain, 77 patients with headache, and 106 patients with non-headache pain), the pain scores as reported during BP measurement and IV cannulation was not significantly different between the patient groups. On sub-group analysis, females reported higher pain scores during IV cannulation than males (2.8±2.6 vs. 2.3±1.9, p=0.06). In addition, married patients had higher pain scores than unmarried patients during both BP measurement (1.31 vs. 1.03, p=0.004) and cannulation (2.73 vs. 2.16, p=0.089).

Conclusion

The differences in pain experienced in patients with or without headache or other causes of pain during IV cannulation and BP measurement were minor. Based on our findings, gender and marital status should be recorded during studies recording pain levels in ED patients.

Thalamic-insular dysconnectivity in schizophrenia: evidence from structural equation modeling

Structural and functional studies have shown that schizophrenia is often associated with frontolimbic abnormalities in the prefrontal and mediotemporal regions. It is still unclear, however, if such dysfunctional interaction extends as well to relay regions such as the thalamus and the anterior insula. Here, we measured gray matter volumes of five right-hemisphere regions in 68 patients with schizophrenia and 77 matched healthy subjects. The regions were amygdala, thalamus, and entorhinal cortex (identified as anomalous by prior studies on the same population) and dorsolateral prefrontal cortex and anterior insula (isolated by voxel-based morphometry analysis). We used structural equation modeling and found altered path coefficients connecting the thalamus to the anterior insula, the amygdala to the DLPFC, and the entorhinal cortex to the DLPFC. In particular, patients exhibited a stronger thalamus-insular connection than healthy controls. Instead, controls showed positive entorhinal-DLPFC and negative amygdalar-DLPFC connections, both of which were absent in the clinical population. Our data provide evidence that schizophrenia is characterized by an impaired right-hemisphere network, in which intrahemispheric communication involving relay structures may play a major role in sustaining the pathophysiology of the disease.

Care provided by general practitioners to patients with psychotic disorders: a cohort study

BACKGROUND

Patients suffering from psychotic disorders have an increased risk of comorbid somatic diseases such as cardiovascular disorders and diabetes mellitus. Doctor-related factors, such as unfamiliarity with these patients, as well as patient-related factors, such as cognitive disturbance and negative symptoms, contribute to suboptimal health care for these patients.General practitioners (GPs) could play a key role in diagnosing and treating this somatic comorbidity as in the Netherlands, almost all residents are registered at a general practice. This study aims to find out whether there are any differences between the levels of health care provided by GPs to patients with psychotic disorders, compared to other types of patients.

METHODS

A cohort of patients with an ICPC code of psychosis and two matched control groups, one consisting of patients with other mental problems and the other one of patients without any mental problems, were followed over a period of 5 years.

RESULTS

Patients with psychotic disorders (N = 734) contacted the GP practice more often than patients in the control groups. These patients, both adults (p = 0.051) and the elderly (p < 0.005), received more home visits from their GPs. In the adult group (16 to 65 years old inclusive), the number of consultations was significantly higher among both psychosis patients and the group of patients with other mental problems (p < 0.0005). The number of telephone consultations was significantly higher in both age categories, adult group (p < 0.0005), and > 65 years old (p = 0.007). With regard to chronic illnesses, elderly psychosis patients had fewer contacts related to cardiovascular diseases or chronic lung diseases.

CONCLUSION

Patients with psychotic disorders contact the GP practice more frequently than other types of patients. Adult psychosis patients with diabetes mellitus, cardiovascular diseases or chronic lung diseases receive the same amount of health care for these diseases as other primary care patients. The finding that older patients with psychotic disorders are diagnosed with cardiovascular diseases and obstructive lung diseases less frequently than other types of elderly patients requires further study.

National estimates of adverse events during nonpsychiatric hospitalizations for persons with schizophrenia

OBJECTIVE

Persons with schizophrenia comprise a vulnerable population that may be disproportionately susceptible to medical injuries. The objective of this study was to determine the association between diagnosis of schizophrenia and adverse events during non-psychiatric hospitalizations.

METHODS

We studied U.S. hospital discharges from 2002-2007 using the Nationwide Inpatient Sample. We determined the nationally weighted association of schizophrenia with the Agency for Healthcare Research and Quality's Patient Safety Indicators after adjusting for patient, hospitalization, and hospital characteristics.

RESULTS

There were 269,387 non-psychiatric hospitalizations with schizophrenia, and 37,092,651 without. Hospitalizations with schizophrenia had elevated adjusted odds ratios for PSIs compared with those without schizophrenia for decubitus ulcer (1.43, 95% CI: 1.36-1.51); infection from medical care (1.19, 95% CI: 1.08-1.30); postoperative respiratory failure (1.96, 95% CI: 1.67-2.30); sepsis (1.59, 95% CI: 1.25-2.02); and pulmonary embolism/deep venous thrombosis (1.23, 95% CI: 1.13-1.35). Adjusted odds ratios for iatrogenic pneumothorax (1.12, 95% CI: 0.94-1.33) and postoperative hemorrhage (1.07, 95% CI: 0.88-1.31) were not significantly different in persons with schizophrenia, while the adjusted OR for accidental puncture (OR=0.66, 95% CI: 0.58-0.74) was reduced in persons with schizophrenia.

CONCLUSIONS

Persons with schizophrenia are more likely to experience the most common types of medical injuries. Improved understanding of factors related to hospital quality of care and outcomes in this group will be important to plan interventions to enhance patient safety for persons with schizophrenia.

Pain reactivity and plasma beta-endorphin in children and adolescents with autistic disorder

BACKGROUND

Reports of reduced pain sensitivity in autism have prompted opioid theories of autism and have practical care ramifications. Our objective was to examine behavioral and physiological pain responses, plasma beta-endorphin levels and their relationship in a large group of individuals with autism.

METHODOLOGY/PRINCIPAL FINDINGS

The study was conducted on 73 children and adolescents with autism and 115 normal individuals matched for age, sex and pubertal stage. Behavioral pain reactivity of individuals with autism was assessed in three observational situations (parents at home, two caregivers at day-care, a nurse and child psychiatrist during blood drawing), and compared to controls during venepuncture. Plasma beta-endorphin concentrations were measured by radioimmunoassay. A high proportion of individuals with autism displayed absent or reduced behavioral pain reactivity at home (68.6%), at day-care (34.2%) and during venepuncture (55.6%). Despite their high rate of absent behavioral pain reactivity during venepuncture (41.3 vs. 8.7% of controls, P<0.0001), individuals with autism displayed a significantly increased heart rate in response to venepuncture (P<0.05). Moreover, this response (Delta heart rate) was significantly greater than for controls (mean+/-SEM; 6.4+/-2.5 vs. 1.3+/-0.8 beats/min, P<0.05). Plasma beta-endorphin levels were higher in the autistic group (P<0.001) and were positively associated with autism severity (P<0.001) and heart rate before or after venepuncture (P<0.05), but not with behavioral pain reactivity.

CONCLUSIONS/SIGNIFICANCE

The greater heart rate response to venepuncture and the elevated plasma beta-endorphin found in individuals with autism reflect enhanced physiological and biological stress responses that are dissociated from observable emotional and behavioral reactions. The results suggest strongly that prior reports of reduced pain sensitivity in autism are related to a different mode of pain expression rather than to an insensitivity or endogenous analgesia, and do not support opioid theories of autism. Clinical care practice and hypotheses regarding underlying mechanisms need to assume that children with autism are sensitive to pain.

[Schizophrenia and pain reactivity]

INTRODUCTION

Medical practitioners do not for a long time pay enough attention to patient's pain. This approach is in the line of society feelings. Pain was long consider to be a contingency to withstand as showed in Christian's bible or Stoicism's principle. Changes in mentality appear in present times. It Seems obvious that for sociological and scientific reasons pain's care in medical and psychiatric disorders is now an important subject. Recent research in autistic disorders suggest that insensitivity observed in autism is not and analgesic phenomenon but a different behavioural reactivity to pain. Prevalence of schizophrenic disorder is from 0.5 to 1%. It is also a complex disorder that has defied decades of concerted efforts to uncover its origins and attenuate its symptoms. The most promising hypotheses suggest that neurodevelopmental impairment increases the risk of later schizophrenia. Most of recent researches in this topic did focus to trait or state markers. According to the vulnerability models of schizophrenia, trait marker are clinical, psychological, physiological, anatomical or cognitive impairments found in patients with schizophrenia during all the course of the illness and even before the onset. Several lines of evidence (case report, epidemiological studies, experimental studies) suggest that patients with schizophrenia shows a relative insensitivity to physical pain. We will review and critic the scientific literature in this specific topic. We will see if datas are relevant with the neurodevelopmental hypothesis and vulnerability models.

METHODS

An OLDMEDLINE/MEDLINE query was performed to identify 50 articles relevant to our subject. 9 were case report or case series, 21 were clinical or epidemiological studies, 15 were experimental studies and we also found 5 previous review.

RESULTS

Clinical and experimental data strongly suggest a decrease of Behavioural Reactivity to Pain (BRP) but there is a lack of argument to prove a real analgesia. Because schizophrenia is a severe disease with impairment in communication and social skills it may be very difficult to affirm that the insensitivity to pain does really exist for patients. It seems inappropriate at this point to speak about insensitivity or analgesia. We could hypothesis that the decrease of BRP is less a consequence of analgesia than a different way to express emotion in general and pain in particular. It is well known that patients with schizophrenia show communication and thinking impairment, not adapted social skills and also a lack of body representation. However, this decrease of behavioural response seems to be frequent and may be explore by objective research protocol to understand if patients don't feel pain or probably don't express pain by adapted social skills. Furthermore, decrease of BRP may take place in a comprehensive theory of schizophrenia. in the line of stress-vulnerability model. Impairment or lack of behavioural pain reactivity could induce an increasing anxiety level for patient with vulnerability to schizophrenia and a higher risk of onset of the pathology. We may argue that pain stimuli would conduct to a nociceptive stress witch couldn't discharge by usual ways of regulation and behavioural expression of pain. Exploration and interview about pain reactivity in vulnerable to schizophrenia subjects could be interesting to increase a the amount of information in a vulnerability check-up. Further studies in this axis may be useful to test this hypothesis.