Clinical Manifestations and Phenomenology
There has been an emphasis on positive and negative symptom clusters in some schizophrenia patients. In the psychiatric litera-ture, positive symptoms have come to mean those that are ac-tively expressed, such as hallucinations, thought disorder, delu-sions and bizarre behavior, whereas negative symptoms reflect deficit states such as avolition, flattened affect and alogia. How these distinct symptom patterns are related in schizophrenia re-mains unresolved.
That schizophrenia could be divided into a two-syndrome concept was put forth by Crow (1980). According to his theory, type I schizophrenia patients are those who present, often more acutely, with a predominantly positive symptom profile and who have a good response to neuroleptics. In contrast, type II schizo-phrenia patients are those who have a more chronic illness, more frequent evidence of intellectual impairment and enlarged ven-tricular size and cortical atrophy as seen on CT or MRI scans, a poorer response to neuroleptics and predominantly negative symptoms. Crow further postulated that type I schizophrenia may be secondary to a hyperdopaminergic state, whereas type II disease may be due to structural abnormality of the brain.
The idea that positive and negative symptoms may be overlapping end points along a single continuum of biological and clinical manifestations has been described by Andreasen and colleagues (1982). In their study of 52 schizophrenia patients, they found that negative symptoms correlated with the presence of ventricular enlargement and that patients with small ventricles were more likely to manifest positive symptoms. In a separate re-port, Andreasen and Olsen (1982) posited that negative and posi-tive symptoms reflect opposite extremes of a spectrum and that a mixed symptom pattern can exist and may be present 30% of the time. Others have suggested that although the positive and nega-tive characteristics may be part of a continuum, they may not be related to the presence or absence of structural brain abnormali-ties; rather, there may be a relationship between the symptom pattern and outcome, depending on the clinical course.
A categorical scheme for differentiation of so-called primary and secondary negative symptoms was developed by Carpenter and colleagues (1985). This distinction is based in part on the fact that negative symptoms are not pathognomonic of schizophrenia. The negative symptoms that can be seen in a number of other illnesses, including depression and medical illness, and as a result of positive symptoms themselves or the side effects of medication, particu-larly extrapyramidal symptoms, are considered “secondary”. The negative symptoms that are a core element of schizophrenia are deemed “primary” or “deficit” symptoms. This distinction enables further exploration of outcome variables and the heterogeneity of this illness and in many ways aids treatment decisions.
Because positive and negative symptoms may be seen dif-ferently by individual psychiatrists, valid psychometric scales have become important clinical and research tools. The Brief Psychiatric Rating Scale (BPRS) (Overall and Gorham, 1961), for example, includes subscales for positive and negative symptoms, as does the Positive and Negative Syndrome Scale (PANSS) for schizophrenia (Kay et al., 1988). Others have more broadly de-fined negative symptoms. Crow (1985) proposed the use of a nar-row definition, that is, flattened affect and poverty of speech, for negative symptoms, and Andreasen (1981) supported a broader definition in the widely used Scale for the Assessment of NegativeSymptoms (SANS). This psychometric scale includes categories of alogia and flattened affect as well as items such as anhedonia, asociality, avolition, apathy and deficits in attention.