Schizophrenia Research Trends

4Reiko Koide and Akira Tamaokareported to herald the onset of schizophrenia (Huber 1957,1971; Rohricht & Priebe, 1997;Schmoll & Koch, 1989; Schmoll, 1994).Disturbances of Pain PerceptionA disorder of proprioception in schizophrenic patients was earlier described by Rado(1959) as a basic element in schizophrenia. He speculated that extensive proprioceptivedeficits could lead to distorted awareness of body image and eventually to the thoughtdisorder characteristic of schizophrenia. Rosenbaum et al. (1965) and Ritzler and Rosenbaum(1974) conducted a series of experiments based on his theory with schizophrenic and nonschizophrenicsubjects using weight discrimination as a measure of proprioception. Theyfound that schizophrenics performed almost as well as normals do when asked to discriminateheavy weights, but did not discriminate light weights nearly as well as normals. Since lightweights do not provide as much proprioceptive feedback as do heavy weights, these resultswere interpreted as demonstrating a proprioceptive deficit in the schizophrenics. Theseresults, however, were not replicated by other authors (Ritzler, 1977; Leventhal et al., 1982),who showed that a proprioceptive deficit is not unique to schizophrenia.Since the time of Kraepelin and Bleuler, “pain insensitivity” or “reduced sensitivity topain” in schizophrenia has been documented. Kraepelin (1919) observed that patients withschizophrenia are often “less sensitive to bodily discomfort; they endure uncomfortablepositions, pricks of a needle, injuries…burn themselves with their cigar, hurt themselves.”Bleuler (1911/1950) noted that even in well-oriented patients one may often observe thepresence of a complete analgesia which includes the deeper parts of the body as well as theskin. The patients “pluck out an eye, sit down on a hot stove and receive severe burns”.Although some authors reported that schizophrenic patients suffer headache (Varsamis &Adamson, 1976; Watson et al., 1981; Philips and Hunter, 1982; Torrey, 1989), the prevalenceof pain complaints in schizophrenia appears to be lower than in other psychiatric disorders(Merskey, 1965; Spear, 1967; Delapaine et al., 1978; Watson et al., 1981). There are manydescriptions of pain insensitivity in schizophrenia by surgeons and internists (Arieti, 1945;Marchand, 1959; West and Hecker, 1952; Vanderkampt, 1970; Apter, 1981, Fishbain 1982;Bickerstaff et al., 1988, Katz et al., 1990; Rosenthal et al., 1990). Dworkin (1994) reviewedthe literature on this issue and argued that the insensitivity, although currently neglected, hasimportant implications for physical health, self-mutilation, homelessness, premorbiddevelopment, and affective flattening in schizophrenic patients. Lautenbacher and Krieg(1994) also reviewed the literature and pointed out that pain insensitivity is important inelucidating pathophysiological mechanisms because pain perception is controlled byneurochemical and neurohormonal functions known to be affected by psychiatric diseaseprocesses. Guieu et al. (1994), however, assessed the pain thresholds of ten schizophrenicpatients and ten controls by measuring the leg flexion nociceptive reflex threshold, andconcluded that in most cases the increase in pain threshold is the result of attitude and notalterations in brain function.