Recovery From Schizophrenia: Psychiatry And Political Economy

WHAT IS SCHIZOPHRENIA? 23system. They have measured differences between people from the generalpopulation, people with schizophrenia and their relatives in their response to suchstimuli as audible clicks and flashing lights. Computerized averaging of multipleelectroencephalograph tracings of subjects’ responses to these stimuli (evokedpotentials) has been used in this work. The research has shown that most peoplewith schizophrenia, as well as half of their close relatives, have an abnormalpattern of response to environmental stimuli. They appear to be overly responsiveto pieces of sensory information—sights, sounds, smells and touch—and morelimited in their ability to blot out irrelevant material. 59It is essential to our capacity to concentrate on what is happening to us that webe able to attend to one aspect of our environment at a time and screen out themultiplicity of other sensory data with which we are constantly bombarded. Thiscapacity to discriminate stimuli and to focus attention may be disrupted in thosewho are vulnerable to schizophrenia. Such a “sensory gating” deficit would be apossible result of abnormal functioning in the limbic system. Given sufficientstress the affected individual will become overwhelmed and highly aroused.Withdrawal into an isolated, inner world may thus be a useful maneuver againstthe effects of the person’s excessive vigilance towards irrelevant stimuli. 60The knowledge that half of the first-degree relatives of people withschizophrenia share a neurophysiological abnormality with those who themselvessuffer from the illness suggests that the defect is transmitted by a single dominantgene. This raises another question, however: why do only some of those with thedefect develop schizophrenia? Using MRI studies, the Colorado team has foundthat people with schizophrenia have a smaller area in the hippocampus (part ofthe limbic system) than their healthy siblings who have the same sensory gatingabnormality. It is possible that early damage to this brain area, combined with aninherited sensory gating defect, is sufficient to produce schizophrenia. 61An interesting wrinkle to this research is the discovery that abnormal sensorygating in schizophrenia is linked to the function of brain nicotine receptors and tothe gene that controls them. The gene in question has been located onchromosome 15. The sensory gating defect is transiently improved by high dosesof nicotine. This finding raises the possibility that some people with schizophreniamay use tobacco as self-medication, and helps to explain why cigarette smoking isheavier and twice as common among people with schizophrenia than in thegeneral population. 62Some research workers, using radioactive tracer substances and brain-imagingtechniques such as single photon emission tomography (SPECT) and positronemission tomography (PET), have demonstrated that blood flow through thefrontal lobes of the brain does not increase in people with schizophrenia, as itdoes in other people, when they undertake tasks requiring attention and effort.People with schizophrenia may not be able to turn on a specific region of theirfrontal lobes, the prefrontal cortex, when needed—a problem that could explainthe withdrawal, apathy and thinking difficulties in schizophrenia. 63 The prefrontal