Motor, volitional and behavioural disorders in schizophrenia: 2. the 'conflict of paradigms' hypothesis

Article Abstract:

Schizophrenic patients exhibit abnormalities in movement, volition, and behavior. These symptoms are usually attributed to either the extrapyramidal (brain regions associated with motor movement such as the basal ganglia), side-effects of antipsychotic (neuroleptic) drugs, or to catatonic disorder. Extrapyramidal phenomena include Parkinsonism symptoms (e.g., slowness, feebleness, and shuffling gait) and symptoms associated with tardive dyskinesia such as such as rigid, abrupt and exaggerated involuntary movements and tics. Catatonic symptoms include persistent, imposed postures, stereotypical movements, bizarre gait, mutism or unintelligible speech, underactivity, and automatic obedience. In an attempt to clarify differences between extrapyramidal and catatonic symptoms, a group of schizophrenic patients aged 18 to 72 years were studied. Seventy-five patients were interviewed examined. Separate interviewers simultaneously rated extrapyramidal side-effects and catatonic phenomena. A second group of 40 patients (including some patients from the first group) were additionally assessed with a modified version of Roger's (1985) Scale for rating motor disorders, which evaluates the degree of each class of symptom and identifies symptoms which could be classified as belonging to either category. Data analysis demonstrated that dyskinesia and catatonic phenomena were both significantly related to illness chronicity. On the Roger's Scale, total extrapyramidal symptom scores were significantly related to total catatonic scores. These findings suggest an interaction rather than a distinction between neuroleptic drug effects and the disease process, and that drug treatment and schizophrenia both induce involuntary movements. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Antipsychotic drugs, Antipsychotic agents, Basal ganglia, Extrapyramidal disorders, Catatonia

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Neural mechanisms of negative symptoms

Article Abstract:

Research has demonstrated that the so-called negative symptoms of schizophrenia, such as the loss of fluent thought and speech, flattened emotions, loss of drive and joy, and attention deficits, all involve frontal lobe functions. Brain imaging techniques such as computerized tomography have made it possible to explore the underlying neural mechanisms of various symptoms and have consistently demonstrated enlargement of the ventricles among long-term schizophrenic patients and a relationship between ventricular enlargement, cognitive impairment and poor functioning prior to onset of the illness. Studies using magnetic resonance imaging to examine sectional portions of the brain in multiple planes have resulted in inconsistent findings. However, functional imaging techniques that measure cerebral blood flow, such as single photon emission computed tomography and positron emission tomography, have demonstrated both decreases in frontal lobe metabolic activity and increases of metabolic activity in the basal ganglia of schizophrenic patients. It is concluded that these coexisting metabolic imbalances may account for the finding that negative and positive symptoms (e.g., hallucinations and delusions) can be generated simultaneously. This is particularly so since many studies show that antipsychotic (neuroleptic) drugs have very little effect on negative symptoms, while positive symptoms respond well to them. Further discoveries relating neurologic mechanisms and schizophrenic symptoms will likely involve complex interactions of neural connective circuits between brain regions. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Brain, Neural transmission, Synaptic transmission

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Schizophrenic syndromes and frontal lobe performance

Article Abstract:

The various types and forms of schizophrenia indicate that several distinct psychophysiological processes contribute to the disorder. To test whether psychomotor poverty (e.g., impairment of abstract thinking and long-term memory) and disorganization (e.g., impaired concentration and inability to learn) are related to different patterns of frontal lobe impairment, 43 chronic schizophrenic patients were studied. Forty-one of the patients were receiving antipsychotic (neuroleptic) medication and 34 were taking antidepressants. The subjects completed a battery of neuropsychological tests to assess schizophrenic syndromes, delusions, hallucinations, formal thought disorder, word fluency, matching ability, and a variety of functions attributed to frontal lobe processes such as flexibility and ability to generate strategies. The more seriously disabled schizophrenics performed poorly on all tests sensitive to frontal lobe damage. Frontal lobe impairments were associated with severity of both psychomotor poverty and disorganization, although no relationships were found between frontal lobe damage site and severity of reality distortion. Disorganization was associated with impaired verbal fluency, and psychomotor poverty was associated with mental dullness and slowness in generating words. These findings seem to indicate that psychomotor poverty and disorganization are related to patterns of frontal lobe impairment, although other schizophrenic syndromes may have different origins. (Consumer Summary produced by Reliance Medical Information, Inc.)

Frontal lobes, Psychomotor disorders

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