Are Patients With Schizophrenia Insensitive to Pain? A Reconsideration of the Question (Bonnot, Anderson, Cohen, Willer, & Tordjman, 2009)

Bonnot, O., Anderson, G., Cohen, D., Willer, J. C., & Tordjman, S. (2009). Are Patients With Schizophrenia Insensitive to Pain? A Reconsideration of the Question. The clinical journal of pain, 25(3), 244-252.

OK… one thing I have to say is that this is the 3^rd or 4^th review paper I have gone through about pain in psychotics… I am starting to feel that much of the information is redundant and will only do a brief notation on this article…

International Association for the Study of Pain (IASP): "(J)ust because someone cannot verbally communicate their state of being doesn't mean they are not experiencing pain and requires no interventions." Schizophrenia, for instance, is a type of mental disease that could involve communication problems and cognitive impairments.

This article reviewed 57 selected articles which could be classified as case reports, clinical and epidemiologic studies, experimental studies and previous review papers.

Discussion

Insensitivity or less reactivity?

I believe the authors' opinion is that the reported pain insensitivity is a result of altered mode of pain expression rather than endogenous analgesia. In addition, the authors also mentioned the assessment problems: the pain measures were not comparable, psychophysical methods are potentially unreliable and, even with signal detection theory, what is intended to measure the sensory discrimination might end up measuring some other processes.

Biochemical Dysfunction?

The opioid and N-methyl-D-aspartate theories of Schizophrenia have been proposed. However, research concerning both hypotheses provided conflicting results.

Decreased behavioral pain expression and stress vulnerability model

The experience of pain results in stress. In ordinary people, the reactions to pain stimuli could be released through normal pain behavior, psychologically or physically. Patients with schizophrenia, on the other hand, can not release the invoked stress through normal reaction channel. As a result, stress might get built up and results in the worsening of psychotic conditions.

review papers

If you ask me why I am going so much into details with these review papers...

Well, I guess that is the process involved in establishing a mental model about pain in psychosis... Given the dearth of literature available for this topic, I shall be able to get a pretty good idea about the "state of the art" literature in this line of research... This will also help me to narrow the topic down...

When I move on to the actual report papers, I would primarily focus on the assessment tools used to measure pain...

Hypoalgesia in schizophrenia is independent of antipsychotic drugs: A systematic quantitative review of experimental studies (Potvin & Marchand, 2008)

Potvin, S., & Marchand, S. (2008). Hypoalgesia in schizophrenia is independent of antipsychotic drugs: A systematic quantitative review of experimental studies. Pain, 138(1), 70-78.

This meta-analysis study containing 12 studies aims to investigate whether patients of schizophrenia have lower pain response when comparing to the normal control groups. In addition, the authors also attempts to examine the impacts of confounding factors on the results of experimental studies; these factors include the nature of pain stimuli, the use of antipsychotic medications, the nature of the psychiatric condition (e.g., process or acute type) and the validity of diagnosis.

The studies about hypoalgelsia fall into four different groups:

• Clinical case reports
  
• Population studies examining the prevalence of pain in patients with schizophrenia
  
• Population studies examining the prevalence of schizophrenia in patients with chronic pain
  
• Experimental studies
  

While mixed findings are found in existing literature about pain perception, there is also a lack of satisfactory explanation for the observations of pain insensitivity in schizophrenia.

The author provides the following as an explanation for the inconclusive findings: "(T)he heterogeneity of patients and the heterogeneity of experimental conditions (, which) may account for heterogeneity of results.

I absolutely agree with this comment because, personally, I have been diagnosed as having delusion disorder, bipolar disorder, schizophrenia, schizoaffective disorder, depression disorder etc. In addition, the diagnosis of schizophrenia has this garbage bag nature—all else don't fit too well.. let's label it schizophrenia… Moreover, what is the nature of pain and how is pain measured? If the notion of pain insensitivity holds true, is it true for all types of pain (e.g., electric shock, thermal stimuli) or is it truer for certain types of stimuli over the others? For instance, although I seem to have fairly high tolerance or threshold for electrical stimuli, I find myself having very low tolerance for heat or thermal stimuli. In addition, taking a multi-dimensional view of pain and different measures might be applied to assess pain of different dimensions (or even same dimensions)… will the results be consistent and why would results on different dimensions have to be consistent?

The studies retained in the analyses of this study have the following characteristics:

• It contained a group of schizophrenia patients
  
• The study contained a control group of healthy people
  
• It was an experimental study where stimuli were given and pain was measured
  
• The study was published between 1952 and 2007
  

The statistics

The reported mean and standard deviation from each study were used to calculate effect size estimate- Hedges' g, which also adjust for sample size, for the schizophrenia patients and the healthy control groups using D-STAT. In this analysis, positive effect size indicates diminished pain response in schizophrenia patients.

The authors also aggregated effect size estimates for each pain measure to generate a mean effect size estimate for each study, which, then, were pooled together to produce a composite effect size estimates. Additional mean effect size estimates were also calculated (see table).

In addition, this study did not find gender and age differences.

The conclusions

Results of this study provide supporting evidence for the notion that schizophrenia patients might have diminished pain responses when compared to health people.

Since analgesic effects were found both in patients medicated with antipsychotic drugs and those not taking medication, such finding casts doubts on the notion that analgesia is a mere artifacts of antipsychotic medications. In addition, some early report on analgesia in psychotic patients were actually published before the introduction of antipsychotic medications.

Since patients with schizophrenia have been found to have blunt response to more than pain (e.g., basic emotion), it is possible that the blunt response is not pain-specific and is more global.

The results found larger effect size when pain is induced using electric stimuli than using thermal stimuli. In other words, all pains are not equal in their effects on patients with schizophrenia.

The authors further provided a critic/recommendations on the short-comings of existing research:

• Future research should take on a multi-dimensional view about pain and use multiple pain assessments to measure "pain."
  
• More electrophysiological studies examining the spinal, autonomic and cortical components of pain are needed.
  
• More studies needed to investigate the relationship between pain perception and schizophrenia.
  
• More studies needed to examine the relationship between the endogenous pain modulation system in schizophrenia.
  

Pain insensitivity in schizophrenia: Trait or state marker? (Singh, Giles, & Nasrallah, 2006)

Singh, M. K., Giles, L. L., & Nasrallah, H. A. (2006). Pain insensitivity in schizophrenia: Trait or state marker? : Journal of Psychiatric Practice Vol 12(2) Mar 2006, 90-102.

This study aims to provide a description for the phenomena of pain insensitivity in schizophrenic patients. It also tries to identify whether pain insensitivity is a trait or a state. In addition, the authors also attempts to propose a "multi-factorial model" based on the analyses of this article. The literature reviewed includes case reports, population-based studies and case series as well as empirical data.

Case reports

All of the patients mentioned in this class of articles did not report the perception of pain. Due to such distorted pain perceptions, their conditions were either misdiagnosed and treatments were delayed, which resulted in the worsening of the morbidity and mortality.

Population-based studies and case series

Prevalence of pain insensitivity in patients with schizophrenia

This type of studies provides a percentage value concerning the lack of pain complaints in conditions where pain should be present. Although many studies emphasized the lower

prevalence of pain complaints, studies have also shown that pain reports are not absent in schizophrenic patients (e.g., Ballenger et al, 1977, and Torrey, 1979). I can attest to this since I have had really bad pains that were incorporated into my delusional system (e.g., thinking I was being attacked by people remotely) when the conditions were so bad that I actually was institutionalized. An absence of pain and decreased pain reaction were also reported in young children who were institutionalized. This type of research could be used as evidence for the trait theory instead of state theory. At the same time, there also exists research that fails to report the decreased sensitivity towards pain in schizophrenic patients. Varsamis and Adamson (1976), for instance, had concluded that only the subgroup of patients marked to be withdrawal failed to report pain. One thing should be noted is that these studies did not utilize comparable pain assessments.

Prevalence of schizophrenia in people with pain

For people with chronic pain and referred to psychiatric treatment, the diagnosis of schizophrenia is far less prevalent than other diagnosis such as anxiety disorder and depression disorder. Some of the studies cited in the article actually found no patients with chronic pain with the comorbidity of schizophrenia. On the other hand, there are also studies finding no evidence of pain insensitivity in schizophrenic patients although more studies are needed to replicate these results.

Empirical data

Currently, there are two methods in this line of studies: psychophysical method and signal detection theory. The psychophysical method involves having subjects reporting the intensity and unpleasantness of the pain signal using words, numbers, line length or handgrip (Gracely, 1984). The major drawbacks of this method is the lack of reliability (Fernandez & Turk, 1992) especially in patients with limited verbal ability.

The second and more recent mode of investigation is the method of signal detection, which attempts to differentiate between the sensory (i.e., sensory discrimination) and affective (i.e., the report that the sensory experiences are painful) perspectives of pain. In this paradigm, patients with schizophrenia are first subjected to thermal, electrical, pinprick, cold pressor and pressured pain. Thereafter, their ability to discriminate the stimuli and their attitudes towards the perceptions of the stimuli are measured. This is considered as the accepted method in measuring pain in psychiatric patients because this is the only method separating the assessment of pain sensory and affect. Yet, this method also has its drawbacks. While what is assumed to measure sensory discrimination might actually be measuring non-sensory process, there is no telling whether the response criteria selected by the researchers really represent what is intended to be measured. Essentially, these are issues concerning the validity of the assessments.

Among the cited literature, following are some of the key findings that catch my eye:

• One study found that schizophrenic patients' reaction to electrical stimuli were "ambivalent" and "dissociated"; such response pattern is similar to that of people with "brain lesion."—No wonder I feel brain dead most of the times. 8-O In addition, this reminds me of the time when I was receiving TENS (transcutaneous electrical nerve stimulation). It did not take me too much time before I hit the top intensity of the signal strength. Moreover, in my much younger years, I went for TENS kind of sessions for "weight loss" purposes. I also hit the top intensity in no time and it was even before the onset of my psychotic symptoms, which seems to speak for the trait theory concerning pain perception. The fact that I seemed to have higher tolerance or higher threshold towards electrical shocks before the onset of my psychosis seem to correspond with the line of research examining the pain sensitivity in health students with family psychiatric history.
  
• Patients with paranoia were less sensitive to pain when comparing patients with other types of schizophrenia.—Since I am so very well endowed with paranoia (whether you believe it or not), am I not supposed to have less sensitivity to pain? In this case, how could I be with chronic pain? On a second thought, what is the possibility that I am actually enduring more pain than I know? 8-O
  
• It is found that patients with chronic schizophrenia are less sensitive to electrical shocks and thermal pain when comparing to those with acute schizophrenia. Am I chronic or not?
  
• Researchers have also tried to figure out the molecular basis for the presumed insensitivity to pain in schizophrenic patients. It has been suggested that there might be abnormal level of serotonin, dopamine, prostaglandins and endorphins in the brain for schizophrenics. Unfortunately, current literature yield conflicting results.
  
• One study found that schizophrenic patients had worsening ability in sensory discrimination but did not differ from the control group in the response criteria required for the reports of pain. Higher response criteria were found to be more correlated with higher degree of flattening affect. The authors thus concluded that the observed insensitivity to pain might have more to do with affective abnormality.
  

It has been suggested, though, that earlier literature were loaded with methodological flaws including issues concerning sample size, diagnostic reliability and the use of control groups. Despite of the presumed methodological improvement in recent studies, there is still a lack of solid literature supporting the "hypoalgesia" in schizophrenic populations.

The author of this review then provided their thoughts about directions for future research etc.

The most important conclusion they had, at least for me, would be that… pain insensitivity seems to be a trait rather than a state. In addition, pain is a multi-dimensional phenomena or, in the authors' words, there need to be a multi-factorial integrated approach to pain perception.

Schizophrenia and pain reactivity (Bonnot & Tordjman, 2008)

Bonnot, O., & Tordjman, S. (2008). Schizophrenia and pain reactivity. La Presse Médicale, 37(11), 1561-1568.

Since this article is actually in French and I don't really read French, following are some of the simple notes I could take about this article.

This is one of the review articles investigating the relationship between psychosis and pain perception. The authors used Medline to search from relevant literature published between the year of 1950 and 2007 and identified 50 articles for further analyses. Among these articles, 5 were previous review papers, 21 were clinical and epidemiological studies and 9 were case reports. One important conclusion of this review is that, although the patients with schizophrenia might exhibit a decreased level of Behavioral Reactivitiy to Pain (BRP), there doesn't seem to be sufficient evidence to prove the notion of insensitivity or anagelsia, which is a neurologic or pharmacologic state within which painful stimuli are perceived but not interpreted as pain.

The definition of pain according to l'Association internationale pour l'étude de la douleur (IASP), French version: « La douleur est une expérience sensorielle et émotionnelle désagréable associée à un dommage tissulaire présent ou potentiel ».

In any case, this would be a good source of references, to.

An appreciation of yoga-therapy in the treatment of schizophrenia. (Machleidt & Ziegenbein, 2008) Abstract

Just found this interesting article speaking of the use of Yoga (or perhpas acupuncture) as a treatment for schizophrenia. Personally, I would stay on my meds until a whole body of literature proves it true.... 8-O

Since I don't have the time to go into the real articles, following is the abstract for the paper..

An appreciation of yoga-therapy in the treatment of schizophrenia. (Machleidt & Ziegenbein, 2008)

Comments on an article by Duraiswamy and colleagues (see record 2007-11830-010). Arun Jha comments in the Letter above on the study by Duraiswamy and colleagues published in the Acta Psychiatrica Scandinavica September issue 2007 reporting unexpectedly positive results. In the Indian cultural environment patients suffering from schizophrenia can possibly be more easily motivated to undergo a yoga therapy than they may be in Europe or South America, as Indian patients are well versed culturally in this method. In Central Europe, in Germany for example, autogenic training has been successfully recommended to patients with schizophrenia for stress reduction. Active physical measures such as running, swimming and cycling, for example, have also been increasingly advocated. The transcultural superiority of yoga therapy over all other CAM may be confirmed some day, as has been the case with acupuncture treatment for pain, but at the moment this open question necessitates a great deal of systematic research across cultural boundaries. It would not be found unwelcome should yoga therapy for schizophrenics come to be accorded the same world wide recognition that acupuncture enjoys for the treatment of pain.

Psychological Causes of Schizophrenia (MacPherson, 2009)

MacPherson, M. (2009). Psychological Causes of Schizophrenia. Schizophrenia Bulletin, 35(2), 284-286.

As I try to look for articles concerning the assessment tools used to evaluate pain in patients with psychosis, I came across this article based on the first person account of a schizophrenic patient in the academic journal titled "Schizophrenia Bulletin."

In this article, the author shares with us the lessons he or she learned for the past 32 years. Through his accounts, the author provides us with a positive example about how patients actually could lead an independent and eventful life through consciously and constantly working on developing coping skills in general as well as in managing additional demands imposed by being a schizophrenic.

It was stated in this article: "In the discharge planning process, I made a conscious decision to return to work." In addition, "One needs to grow in life's experience and cognitive functioning. The help and support of a specialized vocational program…" I cannot agree more.

Ever since the onset of my psychosis about 10 years ago, my psychiatrist and I have been working on keeping me "vocationally functional" if possible. One thing people might not understand is that, the impacts of all health conditions are generally two-folded. One the one hand, you deal with the symptoms associated with the disorders; on the other hand, you also have to deal with the side effects of the treatment such as medication. Interestingly, over two years ago, I would have told you that the above is applicable to mental health condition. It was not until I became a handicapped in chronic pain did I realized that such is applicable to all health conditions.

I have been very lucky in this perspective because my employers have been very accommodating and I have always been able to return or remain at work even when I just got discharged from the psychiatric ward… sustaining high level of psychotic symptoms such as hallucination and delusions as well as having limited cognitive capacity due to both the symptoms and the side effects of the high-dose medications.

However, I do not quite agree with the author concerning the role of parents in the development or maintenance of schizophrenia. Personally, this sounds a bit too much like the classical attachment theory to me… What I believe, instead, is that the development and maintenance of our symptoms are very much dependent on our modus operandi in dealing with all relationships including those with our parents.

I also do not really agree with the statement that "Paranoia and paranoid states and reactions are simply child-like sates similar to a child's temper tantrum." While it is true that some parts of our delusions and hallucinations might have a more childish presence, others do take on a more adult presence. At the same time, some part of the interactions in our delusional worlds might simulate the characteristics of adult-child relationship. However, I don't feel that "a child's temper tantrum could sufficiently explain all symptoms.

I do agree with the notion that "delusions are also based in fear and paranoia and represent a false belief but have a basis in reality." I would also add "guilt" as well. Such opinion is based on my personal experiences. Coincidentally, I have come to this conclusion myself earlier this year or late last year after realizing the "horror" components of my visions, hallucinations and delusions. I have been since pondering about where to start from to resolve issues in me which might have contributed to the manifestation of my psychotic symptoms. Unfortunately, I have yet to find out how to go about doing it.

One thing I cannot stress enough is that… the psychotic symptoms we experience are or could be idiosyncratic to us. For instance, my immigration status to remain in the United States has been an issue for me for a long time, and, the immigration status has also been a major theme in my psychotic symptom. Apparently, such might not be one of the themes for those who are American or who are not aliens wishing to stay in the US.

Most importantly, I am only a fledgling psychotic in that I have only spent about 10 years of experiences dealing with psychotic symptoms etc. There is a high possibility that, as the time goes on and as the learning progress, I might eventually come to fully appreciate what the author tries to convey.

In addition, I am mostly appreciative to both the author and the editors of the journal Schizophrenia Bulletin in the efforts they put forth to publish a case study base the personal account of a Schizophrenic patient. So has it been one of my most deep-seated bias… at point, patients might have something to offer…. at least for the fellow patients...

This writing is cross-posted in the Ratology Reloaded blog.

Evaluation of the pain patient (Leo, 2007)

I think this is a very nice diagram showing the three major components of pain history (Leo, 2007).

Leo, R. J. (2007). Evaluation of the pain patient. In Clinical manual of pain management in psychiatry (pp. 35-62). Washington DC: American Psychiatric Publishing, Inc.