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Schizophrenia Spectrum and Chronic Pain: Is Pain Insensitivity a Myth?

Among patients with schizophrenia, 38% report pain, and the most common pain complaint among individuals with schizophrenia is headaches.
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Schizophrenia  is most notable for its absence from the chronic pain population.1 This may be due to an unfortunate gap in the research—and it is especially important when you consider that pain is associated with reduced quality of life among patients with serious mental illness.2 Patients with schizophrenia have increased rates of serious medical problems,3 are less likely to know or understand their medical difficulties,4 and often receive fragmented or inconsistent medical care.5

The schizophrenia spectrum disorders, including schizotypal personality, delusional, catatonia, brief psychotic, schizophreniform, schizophrenia, and schizoaffective disorders, are organized along a gradient of psychopathology in the updated Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).6 Substance/medication-induced psychotic disorder, psychotic disorder due to another medical condition, and other specified and unspecified schizophrenia spectrum disorders are included as additional classifications. The diagnosis of a schizophrenia spectrum disorder requires the exclusion of another condition that may give rise to psychosis.

The schizophrenia spectrum disorders are defined by abnormalities in 1 or more “positive” and “negative” symptoms. Positive, or added on, symptoms (eg, delusions, hallucinations, disorganized thinking/speech, trouble concentrating, and catatonia) are thought patterns or behaviors that the person with schizophrenia did not have before becoming ill. Negative, or lost, symptoms (eg, apathy, emotionless responses, reduction in speech, social withdrawal, impaired attention, anhedonia, sexual problems, and lethargy) are thought patterns or behaviors that the person had before the illness. Negative symptoms of schizophrenia are not as recognized as the positive symptoms.

The prevalence of schizotypal personality disorder in clinical populations seems to be infrequent (0% to 1.9%), but it is higher in the general population (3.9%).7 The lifetime prevalence of delusional disorder has been estimated at around 0.2%,8 with the most frequent subtype being persecutory.9 Brief psychotic disorder may account for 9% of first-onset psychosis cases in the United States.10 The lifetime prevalence of schizophrenia is approximately 0.3% to 0.7%.11 Schizoaffective disorder is one-third as common,8 and the incidence of schizophreniform disorder is 5-fold less common than schizophrenia.12,13 The prevalence of substance/medication-induced psychotic disorders among individuals presenting with a first episode of psychosis in different settings is between 7% and 25%,14 and the prevalence of psychotic disorders due to another medical condition ranges from 0.21% to 0.54%.8,15

Pain More Common With Schizophrenia

The most common pain complaint among individuals with schizophrenia is headaches.16 Moreover, in a study examining the frequency of pain complaints, 38% of patients who suffer from schizophrenia reported pain.17 In 1981, Watson and colleagues examined the relationship between pain and schizophrenia. They found that patients experience pain from both physical and psychological causes, and the most common pain sites were head, leg, and back.18

More recently, Almeida and colleagues purported that chronic pain was common in patients with schizophrenia, and was similar to the general population of a similar age.19 Birgenheir and colleagues also investigated the pain rates in a sample of veterans diagnosed with schizophrenia.20 They found that 47% reported some type of pain—35% reported arthritis; 22% reported back pain; about 4% reported headache or neuropathic pain; and less than 2% reported migraine,  psychogenic, or chronic pain.

Patients with schizophrenia can present with bizarre sensory complaints, such as “pins and needles” or coenesthesia (unusual or debilitating bodily experiences that do not have an apparent somatic cause).21 These tactile hallucinations may be difficult to distinguish from other pain complaints.22

Do Patients With Schizophrenia Have Pain Insensitivity?

During my review of the literature, the notion of pain insensitivity in individuals with schizophrenia was a pervasive topic. This phenomenon would have important implications for physical health, self-mutilation, homelessness, premorbid development, and affective flattening in individuals with schizophrenia.23 As early as 1911, Bleuler noted the presence of “complete” analgesia when patients with schizophrenia incurred serious injuries (eg, removal of an eye, self-inflicted amputation of the phallus, and sitting on a hot stove).24 In 1919, Kraepelin observed individuals diagnosed with dementia praecox to be less sensitive to bodily discomfort (eg, uncomfortable positions, pricks of a needle, injuries, cigar burns, and self-injurious behaviors).25

In the 1930s and 1940s, Schneider reported “inhuman” self-injury with a lack of pain sensitivity among individuals diagnosed with schizophrenia.26 Reduced pain sensitivity was increasingly reported in clinical experiences by surgeons and internists for a variety of medical conditions or procedures, including third-degree burns,27 arthritis,28 cancer,29 fractures,30 intra-abdominal diseases,31 myocardial infarction,32 and surgery.33

This phenomenon has also been investigated in the laboratory using different types of painful stimuli, including cold pressor,34 electrical,35 imagined,36 pin prick/pressure,37 pinch,38 thermal,39 and warmth and heat pain.40 There are a variety of biological explanations for this phenomenon, including the effects of antipsychotic medications,40 dysregulation of N-methyl-D-asparate (NMDA) receptor-mediated neurotransmission,41 excess endorphins,42 genetic predisposition,43 and motor deficits.44 However, there is little to no physiologic evidence supporting pain insensitivity in schizophrenia.45 There are also other hypotheses, including psychodynamic, psychological, and sociological.46

Last updated on: June 15, 2017
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