Course of positive and negative symptoms - Schizophrenia

The symptoms of schizophrenia are important both clinically and theoretically. There is great interest in identifying the course and characteristics of the symptoms in schizophrenia to determine the differential nature of prognosis and outcome.

Stability of positive and negative symptoms

In his original model, Crow predicted that the negative syndrome would be stable, as it was hypothesized to reflect structural brain damage (Crow 1980; Crow et al. 1981). Studies have generally shown that negative symptoms are more stable than positive symptoms and are the least likely to improve over the course of the illness (Pfohl & Winokur 1982; Pogue-Geile & Harrow 1985; Johnstone et al. 1986; Lindenmayer et al. 1986; Addington & Addington 1991; Andreasen et al. 1991; Hull et al. 1997). In a longitudinal study of symptoms, Arndt et al. (1995) found that the negative symptoms were already prominent at the time of the patients' first episode and remained relatively stable throughout the 2 years in which the patients were followed. The positive symptoms of disorganization and psychoticism were found to be prominent at intake and declined over the course of the follow-up period (Arndt et al. 1995).

Prognostic significance of positive and negative symptoms

Early investigators attempted to distinguish those symptoms that were more likely to predict a good vs. a poor outcome in patients suffering from acute psychosis (Stephens 1978; Vaillant 1978). Yet, despite the sometimes severe distress associated with the psychotic symptoms, it is the negative symptoms which are most closely linked to prognosis. Patients who previously were deemed 'recovered' upon remission from hallucinations and delusions remained unemployed or socially isolated. Many studies have shown that the level of negative symptoms is related to a poor level of psychosocial functioning (Roff & Knight 1978; Johnstone et al. 1979; Knight et al. 1979; Kolakowska et al. 1985; Pogue-Geile & Harrow 1985; Biehl et al. 1986; Keefe et al. 1987; Munk-Jorgensen & Mortensen 1989; Breier et al. 1991; Fenton & McGlashan 1992). However, some studies found that a high level of positive symptoms also correlates with poor functioning (Pogue-Geile & Harrow 1984; Keefe et al. 1987; Breier et al. 1991).

Some retrospective studies have suggested an association between a longer duration of untreated initial psychosis and poor outcome in schizophrenia (Lo & Lo 1977; Inoue et al. 1986; Fenton & McGlashan 1987; Waddington et al. 1995; Scully et al. 1997; Wyatt et al. 1997). However, others have failed to confirm this relationship (Barnes et al. 2000; Craig et al. 2000; Ho et al. 2000). For example, Ho et al. demonstrated no relationship between poor outcome and duration of untreated initial psychosis in a longitudinal study of consistently well-characterized patients which controlled for other prognosticators of schizophrenia such as gender, age of illness onset and premorbid functioning.