In a recent edition of the Schizophrenia Bulletin devoted to negative symptoms, the editor suggested at the beginning of his preface that what he called the “positive–negative symptom distinction” had been introduced into psychiatry only a decade previously (Levine, 1985). Many authors in the same volume seemed to agree with him; at least they did not emphasise any continuity with earlier work. There were a few notable exceptions. Since, for more than 30 years, I have seen the relationship between psychological deficit (cognitive defect, negative syndrome) and the productive (florid, positive) symptoms as lying at the heart of the mystery of schizophrenia, it seemed possible that some account of how that interest arose and developed might still be timely. This is part of the history of the Social Psychiatry Research Unit of the Medical Research Council.

Recent interest in positive and negative symptoms in schizophrenia is fuelled by the hope that this dichotomy will identify components with differing prognostic, therapeutic or pathogenetic significance. Correlations have been sought, and some found, in each of these areas. Yet the origin and definition of negative symptoms remain a matter of debate.

By concentrating on the apparently uncharacteristic stages in the course of schizophrenia, Huber has drawn attention to subjectively basic symptoms (Huber, 1980, 1983; Huber et al, 1979). He has shown in his long-term follow-up investigations of schizophrenic outpatients that uncharacteristic (basic) stages (see below) prevail in the long term when compared with periods of relapse. His new typology of psychopathological outcome underlined these uncharacteristic (purely asthemic) types of remission (“reiner Defekt” — Huber 1957a, 1961, 1966).

Rating scales for negative symptoms, basic symptoms and other comparable psychopathological syndromes were not originally constructed in order to make psychiatric diagnoses. Moreover, these scales were intended to be applied principally to schizophrenic patients. From the point of view of psychological testing their application to non-schizophrenic patients could be rejected on methodological grounds. Nevertheless there are some considerations which may justify such an investigation.

These three papers by psychiatrists from the German-speaking world all deal mainly with the nature and aetiological basis of the psychological deficits manifest as ‘negative’ symptoms in schizophrenic illness. There is just an echo of the controversies regarding the validity of subdivision of schizophrenia into ‘positive’ and ‘negative’ forms that have received much attention from British and North American psychiatrists in recent years. (Andreasen et al, 1982; Crow, 1985). It appears to be implicitly assumed that schizophrenia is a unity. The acute psychoses which are diagnosed as schizophrenic in most countries but named ‘psychogenic psychoses’ in Scandinavia and ‘bouffée delirante’ in France and ‘emotion psychoses’ in Switzerland (Labhardt, 1963) are not allowed to complicate matters.

It has become customary to classify the typical abnormalities of the mental state of schizophrenic patients into positive and negative features, with reference to behavioural excesses and deficits. Positive features are pathological by their presence and negative features represent the loss of some normal function. Positive features are generally considered to include delusions, hallucinations and positive formal thought disorder (Fish, 1962). Some studies (e.g. Johnstone et al, 1978) have also included incongruity of affect under this heading. Negative features include affective flattening, poverty of speech, retardation, apathy, lack of sociability. There is some evidence that the clinical correlates of positive and negative features may not be the same (Owens & Johnstone, 1980). Some workers (Andreasen & Olsen, 1982) but not others (Pogue-Geile & Harrow, 1984) have found that among schizophrenic patients positive and negative symptoms were negatively correlated. Although the nature of the relationship between positive and negative features is not entirely established and may not be simple (Wing, 1978) certain generalisations may be applied:

1. (a) Positive features are characteristic of earlier and negative of later phases of the illness (Pfohl & Winokur, 1982).

2. (b) The effects of drugs upon positive features are greater than those upon negative features. Thus neuroleptics produce more marked improvement (Johnstone et al, 1978; Angrist et al, 1980) and amphetamine more marked exacerbation (Angrist et al, 1980) of positive than of negative features.

3. (c) Positive features have been said to be relatively variable and negative features relatively stable (Ovchinnikov, 1968; Snezhnevsky, 1968).

The Manchester Scale (Krawiecka et al, 1977) was developed as a short, easy to administer instrument, sensitive to change, for screening patients with chronic psychosis.

In making these ratings the psychiatrist is expected to use his clinical judgement to make overall assessments about the patients in each particular area. For example, in making the rating for depression the rater should be expressing his own clinical assessment of the severity of depression, based on both the patient's demeanour and behaviour during the interview, and the history that the patient has given concerning depression. It should be emphasised that a morbid rating (2, 3, or 4) for depression does not imply that the principal diagnosis made will necessarily be an affective illness.

The Scale for the Assessment of Negative Symptoms (SANS) was the first instrument developed in order to provide for comprehensive assessment of negative symptoms in schizophrenia (Andreasen, 1982, 1983). It consists of five scales that evaluate five different aspects of negative symptoms: alogia, affective blunting, avolition-apathy, anhedonia-asociality, and attentional impairment. Each of these negative symptoms can be rated globally, but in addition detailed observations are made in order to achieve the global rating. It is complemented by a Scale for the Assessment of Positive Symptoms (SAPS), which permits detailed evaluation and global ratings of hallucinations, delusions, positive formal thought disorder and bizarre behaviour (Andreasen, 1984). Taken together, the two scales provide a comprehensive set of rating scales in order to measure the symptoms of schizophrenia and to assess their change over time.

The Scale for the Assessment of Negative Symptoms (SANS) was developed in order to facilitate evaluation of five important symptoms frequently observed in ‘core schizophrenia’ (process schizophrenia, the schizophrenic defect state, negative schizophrenia). These symptoms include affective flattening, alogia (poverty of speech and thought), avolition, anhedonia, and attentional impairment.

Over 75 years ago, Bleuler (1911) confronted psychiatry with the question of ‘schizophrenia’ or ‘schizophrenias'. Today we recognise the heterogeneity of the condition, but we are still groping at efforts to clarify the different subtypes or subprocesses. Over the decades there have been various attempts to subclassify schizophrenia and tease apart the syndromes, none of which has been entirely successful. More recently, as a result of the work by Crow (1980) in England and Strauss et al (1974) in the USA, it has been proposed that two distinct syndromes can be discerned from the phenomenological profiles. The positive syndrome consists of productive features superadded to the mental status, such as delusions, hallucinations, and disorganised thinking. The negative syndrome represents absence of normal functions, such as deficits in the cognitive, affective, and social realms.

Diminished emotional responsiveness as characterised by a reduction in facial expression, modulation of feelings, and communicative gestures. Basis for rating: observation of physical manifestations of affective tone and emotional responsiveness during the course of interview.

Based on the experience with the International Pilot Study on Schizophrenia (IPSS) (WHO 1973, 1979), the WHO Division of Mental Health and Centres in Sofia, Groningen and Mannheim, joined by expertise from Nottingham and Zurich, conceived a prospective study to assess the ‘natural history’ (Ciompi, 1980a, b; Watt et al, 1983; Biehl, 1987) of psychological impairments and social disabilities in patients with functional psychosis in different socio-cultural environments (Jablensky et al 1980).

Trimble (1986) has pointed out a shortcoming of the current wave of literature on negative symptoms: there is no overall consensus within psychiatry as to which symptoms and signs are to be considered positive and which negative (Kayton, 1973; Carpenter et al, 1976; Sheldrich et al, 1977; WHO, 1979; Andreasen, 1979; Jablensky, 1981; Crow, 1982, this volume; Rosen et al, 1984; Zubin, 1985; Kulhara et al, 1986).

The Psychological Impairments Rating Schedule (PIRS) was originally designed by the WHO (Jablensky, 1978; see also Biehl et al this volume) and was used as a supplement to the Present State Examination (PSE) (Wing et al, 1974) in a number of collaborative WHO studies. It was mainly designed for assessing selected areas of psychological and behavioural impairments (or deficits) in patients who have suffered, or are suffering, from functional psychotic disorders. It comprised items and scales for rating observed behaviour and was filled in immediately or soon after a psychiatric or PSE interview. Raters were encouraged to take note of a subject's current behaviour and function both before and after the interview proper. The first two sections of PIRS included all behavioural items of PSE (ninth edition). Sections 18–20 as well as a number of items taken from other psychopathological rating scales and items formulated de novo.

Consider:

1. (i) the most striking characteristics of the subject in general appearance and gait;

2. (ii) conforming to social routines and conventions;

3. (iii) physical appearance;

4. (iv) skills in presenting a favourable façade of own personality and concealing unfavourable aspects.

The concept of deterioration has always been central to schizophrenia, and forms a cornerstone of current diagnostic and conceptual thinking (e.g. DSM–III; Crow, 1985; Weinberger, 1987). Recently, there has been a renewal of interest in the deficits of schizophrenia, with attempts to identify, classify, and measure the relevant abnormalities. According to current thinking (Crow 1985; Wing, this volume) negative symptoms i.e. deficits in emotion, volition and social interaction, represent a distinctive cluster of impairments with aetiological, prognostic and therapeutic significance. Verification of this view of course requires reliable and valid measures of negative symptoms.