Schizophrenia Research, 5 (1991) 51-59 Elsevier
SCHIZO
51
00160
Positive and negative symptoms of schizophrenia Their course and relationship Jean
Addington’
and
over time
D. Addington
‘Department of Psychology, Holy Cross Hospital, Calgary, and Department of Psychiatry, University of Calgary, Calgary, Canada, and ‘Faculty of Medicine, University of Calgary, Calgary, Canada (Received
26 January
1990, revised received
27 August
1990, accepted
1 September
1990)
Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms. It is sometimes assumed that positive and negative symptoms are distributed discontinuously or inversely. Many of the studies that have examined this concept are cross-sectional. This research examines the relationships among positive and negative symptoms in a sample of 41 DSM III diagnosed schizophrenics. Using the SANS and the SAPS, symptoms are assessed, first, in the acute phase of the illness and then, 6 months later, in a period of relative remission. Results showed that positive and negative symptoms were not inversely related at either phase of the illness. Secondly, in comparison to positive symptoms, negative symptoms were highly intercorrelated at both times. Thirdly, the presence of negative symptoms in the acute phase was highly predictive of the presence of negative symptoms at follow-up. Implications for the longitudinal course of symptoms in schizophrenia are discussed. Key words: Positive
symptom;
Negative
symptom;
Course;
(Schizophrenia)
INTRODUCTION
Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms (Crow, 1980a,b; Andreasen, 1982). There have also been suggestions of a type I and type II schizophrenia (Crow, 1980a,b). Crow conceives positive and negative symptoms as two independent variables that may or may not occur in the same patient. He maintains that while the two syndromes reflect different pathological processes they do not constitute separate diseases since they commonly occur together either simultaneously or at different points in time. Alternatively, Andreasen and Olsen (1982) have suggested that positive and negative symptoms Correspondence IO: J. Addington, Department of Psychology, Holy Cross Hospital, 2210, 2nd Street, SW., Calgary, Alberta T2S 1S6. Canada.
0920-9964/91/$03.50
0
1991 Elsevier Science Publishers
B.V.
might be negatively correlated: that is patients with positive symptoms lie at one end of a continuum from patients with negative symptoms, with the mixed group lying somewhere in between. In contrast, Pogue-Geile and Harrow (1984) contend that, although they appear to represent different processes, longitudinally, there seems to be some kind of relationship between positive and negative symptoms. A number of other studies have also found that when positive and negative symptoms are assessed cross-sectionally there is no significant correlation between the scales (Green and Walker, 1985; Kay et al., 1986; Lindenmeyer et al., 1986; Walker et al., 1988; Guelfi et al., 1989). In a further examination, using factor analysis, Bilder et al. (1985) and Liddle (1987) report finding two or more independent dimensions: one loading primarily on negative symptoms; and the others primarily on positive symptoms. Again this is in direct contrast to the results of Andreasen and Olsen (1982).
52
These above mentioned studies utilized patients in the acute stage of their illness. However, when patients have been followed longitudinally (e.g., Pogue-Geile and Harrow, 1984; Lindenmeyer et al., 1986) positive and negative symptoms are statistically independent. In their review, PogueGeile and Zubin (1988) conclude that when assessed cross-sectionally positive and negative symptoms are independent dimensions, but that the positive longitudinal relationship between the two is often overlooked. They suggest that perhaps negative symptoms are more common in patients who have at some time experienced positive psychotic symptoms. Few studies have examined the persistence of negative symptoms over time. Lindenmeyer et al. (1986) did not find a test-retest correlation to be significant. In comparison, Pogue-Geile and Harrow (1985) reported that 55% of patients reported negative symptoms 2 years after their initial assessment. The purpose of this present study is to examine, at both the hospitalization phase of the illness and 6 months later, the relationship between positive and negative symptoms and to determine if the presence of certain symptoms in the acute phase is predictive of certain symptoms at follow-up.
METHODOLOGY Subjects The sample consisted of 41 schizophrenics (27 males and 14 females). Subjects were required to have a DSM III diagnosis of schizophrenia based on data from interview with the Present State Examination and chart review. Subjects were excluded if they had any of the following: (1) evidence of an organic central nervous system disorder; (2) significant and habitual drug or alcohol abuse in the past year; (3) mental retardation. The sample had an average age of 30.9 years (range= 17-54 years; SD=8.73), and an average of 11.5 years of education. The average number of admissions of this sample was 5.26 (range l-16, SD=3.70) and the average age of onset was 22.4 years. There were no significant relationships among either years of education or number of admissions and positive and negative symptoms. Males exhibited more flat affect at time I and II
(Y= 0.32, P < 0.05); and more anhedonia at time II (r=0.38, PcO.05) than female subjects. The females exhibited more hallucinations at time II (Y= 0.33, PcO.05) than males. Age of onset was significantly related to thought disorder at both phases (r=0.32 and r=0.38, P~0.05) and to bizarre behavior at time II (r =0.33, P~0.05). All subjects were taking antipsychotic medication at the time of the first assessments. At followup all but two patients were on maintenance doses of medication. Chlorpromazine equivalents were calculated and there were no significant associations between medication dose and any of the positive or negative symptoms. The two patients who were not on any medication at follow-up, were not symptom free and their symptom scores did not differ significantly from the mean symptom scores of the patients on medication. Test instruments All patients were rated on negative symptoms and positive symptoms using the Scale for the Assessment of Negative Symptoms (SANS) (Andreasen, 1981) and the Scale for the Assessment of Positive Symptoms (SAPS) (Andreasen, 1984). Each symptom in the scale was rated from severe (5) to absent (0). The symptom ratings were summed to provide a global score for positive symptoms and a global score for negative symptoms. Procedures Subjects were assessed privately. The first assessment was conducted during hospitalization. These assessments began as soon as patients were fit to give consent (usually 3-7 days after admission). Assessments were repeated 6 months later during a period of relative remission. At this time, only two of the subjects were in hospital. The PSE, the SANS, and the SAPS were administered by D.A., who had established his interrater reliability of these measures on a sample of videotapes at the UCLA Clinical Research Center for Schizophrenia. Interrater reliability for symptom presence was 85% on the PSE and on the SANS.
RESULTS
Pearson product moment correlations were used to examine relationships among the different symp-
53
toms ratings at both time periods to see if there were any general symptom dimensions underlying the positive and negative scales. A varimax rotation was applied to a principle components solution. At time I (Table 7) only two factors had eigenvalues greater than 1. Negative symptoms had significant loadings on factor 1 and accounted for 52% of the variance. Formal thought disorder loaded significantly’on factor 2 and accounted for
toms. Intercorrelations among the positive symptoms are presented in Tables 1 and 2. More intercorrelations were noted among positive symptoms in the follow-up period. Tables 3 and 4 show the high intercorrelations among all negative symptoms at both time periods. The relationships between positive and negative symptoms are presented in Tables 5 and 6. Factor analyses were conducted on the sympTABLE
I
Intwcorrelations
among positive
symptoms
at time I
Hallucinations
Symptom
Delusions
Bizarre
Formal
behavior
thought disorder
Hallucinations Delusions
1 -0.17
Bizarre behavior Formal thought disorder Total positive symptom score
-0.08 0.39* 0.42**
_ 1
_
I
0.12 -0.01 0.19
I
0.34** 0.72**
0.47**
Bizarre
Formal
*p
SCHIZO
51
00160
Positive and negative symptoms of schizophrenia Their course and relationship Jean
Addington’
and
over time
D. Addington
‘Department of Psychology, Holy Cross Hospital, Calgary, and Department of Psychiatry, University of Calgary, Calgary, Canada, and ‘Faculty of Medicine, University of Calgary, Calgary, Canada (Received
26 January
1990, revised received
27 August
1990, accepted
1 September
1990)
Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms. It is sometimes assumed that positive and negative symptoms are distributed discontinuously or inversely. Many of the studies that have examined this concept are cross-sectional. This research examines the relationships among positive and negative symptoms in a sample of 41 DSM III diagnosed schizophrenics. Using the SANS and the SAPS, symptoms are assessed, first, in the acute phase of the illness and then, 6 months later, in a period of relative remission. Results showed that positive and negative symptoms were not inversely related at either phase of the illness. Secondly, in comparison to positive symptoms, negative symptoms were highly intercorrelated at both times. Thirdly, the presence of negative symptoms in the acute phase was highly predictive of the presence of negative symptoms at follow-up. Implications for the longitudinal course of symptoms in schizophrenia are discussed. Key words: Positive
symptom;
Negative
symptom;
Course;
(Schizophrenia)
INTRODUCTION
Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms (Crow, 1980a,b; Andreasen, 1982). There have also been suggestions of a type I and type II schizophrenia (Crow, 1980a,b). Crow conceives positive and negative symptoms as two independent variables that may or may not occur in the same patient. He maintains that while the two syndromes reflect different pathological processes they do not constitute separate diseases since they commonly occur together either simultaneously or at different points in time. Alternatively, Andreasen and Olsen (1982) have suggested that positive and negative symptoms Correspondence IO: J. Addington, Department of Psychology, Holy Cross Hospital, 2210, 2nd Street, SW., Calgary, Alberta T2S 1S6. Canada.
0920-9964/91/$03.50
0
1991 Elsevier Science Publishers
B.V.
might be negatively correlated: that is patients with positive symptoms lie at one end of a continuum from patients with negative symptoms, with the mixed group lying somewhere in between. In contrast, Pogue-Geile and Harrow (1984) contend that, although they appear to represent different processes, longitudinally, there seems to be some kind of relationship between positive and negative symptoms. A number of other studies have also found that when positive and negative symptoms are assessed cross-sectionally there is no significant correlation between the scales (Green and Walker, 1985; Kay et al., 1986; Lindenmeyer et al., 1986; Walker et al., 1988; Guelfi et al., 1989). In a further examination, using factor analysis, Bilder et al. (1985) and Liddle (1987) report finding two or more independent dimensions: one loading primarily on negative symptoms; and the others primarily on positive symptoms. Again this is in direct contrast to the results of Andreasen and Olsen (1982).
52
These above mentioned studies utilized patients in the acute stage of their illness. However, when patients have been followed longitudinally (e.g., Pogue-Geile and Harrow, 1984; Lindenmeyer et al., 1986) positive and negative symptoms are statistically independent. In their review, PogueGeile and Zubin (1988) conclude that when assessed cross-sectionally positive and negative symptoms are independent dimensions, but that the positive longitudinal relationship between the two is often overlooked. They suggest that perhaps negative symptoms are more common in patients who have at some time experienced positive psychotic symptoms. Few studies have examined the persistence of negative symptoms over time. Lindenmeyer et al. (1986) did not find a test-retest correlation to be significant. In comparison, Pogue-Geile and Harrow (1985) reported that 55% of patients reported negative symptoms 2 years after their initial assessment. The purpose of this present study is to examine, at both the hospitalization phase of the illness and 6 months later, the relationship between positive and negative symptoms and to determine if the presence of certain symptoms in the acute phase is predictive of certain symptoms at follow-up.
METHODOLOGY Subjects The sample consisted of 41 schizophrenics (27 males and 14 females). Subjects were required to have a DSM III diagnosis of schizophrenia based on data from interview with the Present State Examination and chart review. Subjects were excluded if they had any of the following: (1) evidence of an organic central nervous system disorder; (2) significant and habitual drug or alcohol abuse in the past year; (3) mental retardation. The sample had an average age of 30.9 years (range= 17-54 years; SD=8.73), and an average of 11.5 years of education. The average number of admissions of this sample was 5.26 (range l-16, SD=3.70) and the average age of onset was 22.4 years. There were no significant relationships among either years of education or number of admissions and positive and negative symptoms. Males exhibited more flat affect at time I and II
(Y= 0.32, P < 0.05); and more anhedonia at time II (r=0.38, PcO.05) than female subjects. The females exhibited more hallucinations at time II (Y= 0.33, PcO.05) than males. Age of onset was significantly related to thought disorder at both phases (r=0.32 and r=0.38, P~0.05) and to bizarre behavior at time II (r =0.33, P~0.05). All subjects were taking antipsychotic medication at the time of the first assessments. At followup all but two patients were on maintenance doses of medication. Chlorpromazine equivalents were calculated and there were no significant associations between medication dose and any of the positive or negative symptoms. The two patients who were not on any medication at follow-up, were not symptom free and their symptom scores did not differ significantly from the mean symptom scores of the patients on medication. Test instruments All patients were rated on negative symptoms and positive symptoms using the Scale for the Assessment of Negative Symptoms (SANS) (Andreasen, 1981) and the Scale for the Assessment of Positive Symptoms (SAPS) (Andreasen, 1984). Each symptom in the scale was rated from severe (5) to absent (0). The symptom ratings were summed to provide a global score for positive symptoms and a global score for negative symptoms. Procedures Subjects were assessed privately. The first assessment was conducted during hospitalization. These assessments began as soon as patients were fit to give consent (usually 3-7 days after admission). Assessments were repeated 6 months later during a period of relative remission. At this time, only two of the subjects were in hospital. The PSE, the SANS, and the SAPS were administered by D.A., who had established his interrater reliability of these measures on a sample of videotapes at the UCLA Clinical Research Center for Schizophrenia. Interrater reliability for symptom presence was 85% on the PSE and on the SANS.
RESULTS
Pearson product moment correlations were used to examine relationships among the different symp-
53
toms ratings at both time periods to see if there were any general symptom dimensions underlying the positive and negative scales. A varimax rotation was applied to a principle components solution. At time I (Table 7) only two factors had eigenvalues greater than 1. Negative symptoms had significant loadings on factor 1 and accounted for 52% of the variance. Formal thought disorder loaded significantly’on factor 2 and accounted for
toms. Intercorrelations among the positive symptoms are presented in Tables 1 and 2. More intercorrelations were noted among positive symptoms in the follow-up period. Tables 3 and 4 show the high intercorrelations among all negative symptoms at both time periods. The relationships between positive and negative symptoms are presented in Tables 5 and 6. Factor analyses were conducted on the sympTABLE
I
Intwcorrelations
among positive
symptoms
at time I
Hallucinations
Symptom
Delusions
Bizarre
Formal
behavior
thought disorder
Hallucinations Delusions
1 -0.17
Bizarre behavior Formal thought disorder Total positive symptom score
-0.08 0.39* 0.42**
_ 1
_
I
0.12 -0.01 0.19
I
0.34** 0.72**
0.47**
Bizarre
Formal
*p
