Characteristic Symptoms Of Schizophrenia

The characteristic features of schizophrenia are hallucinations and delusions, disorders of thought and speech, disorders of behaviour, disturbance of emotions and affect, cognitive deficits and avolition.

Hallucinations and delusions are frequently observed at some time during the course of schizophrenia. According to Cutting [13], visual hallucinations occur in 15%, auditory in 50% and tactile in 5% of all subjects, and delusions in more than 90%. Particular diagnostic importance has been attributed to specific delusions and hallucinations.

Kurt Schneider [9] had identified a number of specific delusions and hallucinations that he considered to be pathognomonic of schizophrenia and for which he coined the term ''first-rank symptoms''. The concept was included in DSM-III, but has been given much less prominence in DSM-III-R and DSM-IV. It has been retained in the ICD-10 definition of schizophrenia. The issue of Schneiderian first-rank symptoms is discussed in detail below.

In DSM-III, DSM-III-R and DSM-IV, bizarre delusions have been attributed major diagnostic importance, in that the presence of any delusion of this kind qualifies for a diagnosis of schizophrenia, even if it is the only symptom. The definition of ''bizarre'' has, however, been changed in DSM-III-R. In DSM-III, bizarre delusions were defined as false beliefs whose content is patently absurd and which have no possible basis in fact, that is, such delusions would be

"impossible". The DSM-III-R definition indicated that such delusions would be "implausible", that is, that they involve a phenomenon that the person's culture would regard as impossible. The concept has remained controversial, in particular because inter-rater reliability in the evaluation of a delusion as bizarre or non-bizarre is poor [14,15].

The term thought disorder refers to a disorder of the content as well as of the form of a person's thoughts. Delusions are a disorder of the content of a person's thoughts. Disorders in the form of thought may be subdivided in two categories [16]: an intrinsic disturbance of thinking; and a disorder of the form in which thoughts are expressed in language and speech.

The intrinsic disturbance of thinking encompasses concrete thinking, over-inclusion, illogicality and loosening of associations. Disordered language and speech include derailment, tangentiality, neologisms, poverty of speech, poverty in the content of speech, incoherence, pressure of speech, flight of ideas and retarded speech or mutism.

Evaluation of formal thought disorder has been handicapped for many years by the lack of generally accepted definitions of the disturbance. Andreasen [17] provided definitions for 18 varieties of formal thought disorder as well as examples from the speech of patients. The reliability of these definitions was found to be quite good for most of the terms defined. Of the 18 definitions, only six had weighted kappa values below 0.6: tangentiality, clanging, echolalia, self-reference, neologisms and word approximations. All other varieties, including derailment, incoherence and poverty of speech, had good to excellent kappa values.

The frequency and specificity of formal thought disorder in schizophrenia vary considerably from one subtype to the other. According to Cutting and Murphy [18], not all patients with schizophrenia had intrinsic thought disorder and those that did tended to have over-inclusive categorization as the most apparent manifestation. According to Andreasen [17], some types of thought disorder, such as neologisms or blocking, occur so infrequently as to be of little diagnostic value. Other types are common in schizophrenia, but do not distinguish patients with schizophrenia from patients with mania (e.g. derailment) or depression (e.g. poverty of speech). As a consequence, formal thought disorder should not be used as a diagnostic criterion for the diagnosis of schizophrenia except in the absence of affective symptoms.

Disorders of behaviour in schizophrenia include grossly disorganized behaviour and catatonic behaviour. From the beginning, catatonic behaviour has been described among the characteristic features of schizophrenia. Cutting [19] defines catatonia as a set of complex movements, postures and actions whose common denominator is their involuntariness. Catatonic phenomena include: stupor, catalepsy, automatism, mannerisms, stereo-typies, posturing and grimacing, negativism and echopraxia. Catatonic symptoms have been found in 7% [20] and between 5 and 10% [21] of patients with schizophrenia. Catatonic symptoms are not specific to schizophrenia. In particular, they may occur in mania [22].

Anhedonia or loss of feelings, and disorders of affect such as inappropriate affect and blunting or flattening of affect, are among the characteristic disturbances of emotions and affect that are classically associated with the diagnosis of schizophrenia.

Anhedonia or loss of feeling has been proposed as a central [23] or cardinal [24] feature of schizophrenia. Chapman et al [25] designed questionnaires of social and physical anhedonia. Physical anhedonia covers pleasures such as admiring the beauty of sunsets, eating, drinking, singing, being massaged. Social anhedonia covers pleasures such as being with friends or being with other people. In a study by Watson et al [26], anhedonia was significantly more frequent in patients with schizophrenia than in patients with alcohol dependency. In a recent study by Blanchard et al [27], patients with schizophrenia reported significantly greater physical and social anhe-donia than controls. In a study by Cook and Simukonda [28], social but not physical anhedonia was significantly higher in patients with schizophrenia than in subjects from a hospital staff control group. Concerning the specificity of anhedonia, Harrow et al [29] found that only chronic, not acute, schizophrenics were significantly anhedonic. According to Schuck et al [30], physical anhedonia was no more prevalent in patients with schizophrenia than in patients with depression.

In a study by Andreasen [31], inappropriate affect occurred in 20% of acutely ill patients with schizophrenia, and flattening of affect in 50% of acute or chronic patients. Inappropriate affect had poor reliability. The symptom appeared significantly more often in patients with schizophrenia than in patients with mania or depression. Affective flattening was found to be common but not omnipresent in patients with schizophrenia, and was also common in depressed patients. Abrams and Taylor [32] documented that affective blunting distinguished between a group of patients with manic symptoms and a group with schizophrenic symptoms.

Cognitive deficits have been listed among the central features of schizophrenia since the original descriptions of Kraepelin and Bleuler.

Patients with schizophrenia demonstrate a generalized cognitive deficit, that is, they tend to perform at lower levels than do normal controls across a broad variety of cognitive tests [33]. Braff et al [34] compared patients with schizophrenia with normal controls. Patients with schizophrenia had multiple neuropsychological deficits on tests of complex conceptual reasoning, psycho-motor speed, new learning and incidental memory, and both motor and sensory-perceptual abilities. Saykin et al [35] showed that patients demonstrated generalized impairment relative to controls and a selective deficit in memory and learning compared with other functions. According to Goldberg et al [36], patients with schizophrenia perform systematically worse on cognitive measures than patients with affective disorders.

Prominent selective cognitive abnormalities in schizophrenia include deficits in attention, memory and problem solving:

• Attentional dysfunction has been observed in patients with schizophrenia on a number of neuropsychological tests, including tests of immediate attention span, sustained attention, visual search and tracking, selective attention, and executive control of attention [37]. In particular, sustained attention has been investigated in many studies and consistently found to be defective in patients with schizophrenia [38].

• According to Goldberg and Gold [39], patients with schizophrenia demonstrate marked deficits in episodic memory measures; procedural learning that involves motor skills may be relatively intact, and the situation for item-specific implicit memory is unclear.

• Patients with schizophrenia appear to have difficulties in solving problems whose solutions are not readily apparent, or when they must rely upon novel recombinations of existing knowledge [39, 40]. Deficits have been observed in a wide variety of instruments, stimulus materials and response modalities, including the Wisconsin Card Sorting Test [34, 41].

Apathy, abulia, lack of will or avolition are terms that have been applied to characterize a fundamental inability to initiate and persist in goal-directed activities. Avolition is usually included among the characteristic symptoms of schizophrenia. In particular, avolition-apathy is included among the negative symptoms of the disorder [42, 43].

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