The Assessment of Negative and Positive Features in Schizophrenia

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: (a)Positive features are characteristic of earlier and negative of later phases of the illness (Pfohl & Winokur, 1982).(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.(c)Positive features have been said to be relatively variable and negative features relatively stable (Ovchinnikov, 1968; Snezhnevsky, 1968).