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Elevated levels of cognitive-perceptual deficits in individuals with a family history of schizophrenia spectrum disorders
Schizophrenia Research 46 (2000) 57–63 www.elsevier.com/locate/schres
Elevated levels of cognitive-perceptual deficits in individuals with a family history of schizophrenia spectrum disorders Pauline S. Yaralian a, Adrian Raine a, *, Todd Lencz b, Jill M. Hooley c, Susan E. Bihrle a, Shari Mills a, Joseph Ventura d a Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, USA b Department of Research, Hillside Hospital (North Shore Long Island Jewish Health System), 75-59 263rd St., Glen Oaks, NY 11004, USA c Department of Psychology, Harvard University, Boston, MA 02138, USA d UCLA Department of Psychiatry and Biobehavioral Sciences, Los Angeles, CA 90095–6968, USA Received 14 July 1999; accepted 30 November 1999
Abstract This study finds that the relatives of schizophrenics have elevated scores on the cognitiveperceptual factor of the schizotypal personality questionnaire (SPQ), particularly for the ‘unusual perceptual experiences’ and ‘ideas of reference’ subscales. These results support recent findings by Kremen et al. (1998) and suggest that previous failures to demonstrate elevated scores on ‘positive’ symptoms of schizotypy may be a function of instrumentation. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Cognitive-perceptual; Schizophrenia; Schizotypal personality disorder; SPQ
1. Introduction Research in the area of individual differences in schizotypy using self-report techniques has taken two approaches. First, measures of ‘psychosis proneness’ have been developed to assess some of the positive [magical ideation, Eckblad and Chapman, 1983; perceptual aberration scale (PAS), Chapman et al., 1978] and negative features of schizotypy (physical anhedonia scale, Chapman et al., 1976; social anhedonia scale, Chapman et al., 1976). The second approach is based on the conceptualization of schizotypal personality disorder (SPD) found in the DSM-III-R (APA, 1987) and DSM-IV (APA, 1994) and
* Corresponding author.
includes nine features. The schizotypal personality questionnaire (SPQ, Raine, 1991) is modeled on DSM-III-R criteria for SPD and consists of subscales for all nine schizotypal features. Research on the psychosis-proneness scales and the SPQ has amassed a significant body of psychometric data indicating that they are useful indicators of psychosis-proneness (Chapman et al., 1995; Raine et al., 1995). However, attempts to validate these scales against first-degree relatives of schizophrenics and psychotic patients have produced conflicting findings. Clementz et al. (1991) administered psychosis-proneness measures to the firstdegree relatives of schizophrenics. They found that the first-degree relatives of schizophrenics scored higher on the physical anhedonia scale relative to controls who lacked psychotic disorders both in themselves and their first-degree relatives.
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However, their scores on the PAS, which taps some of the more ‘positive’ features of psychosisproneness, were significantly lower than the controls. Katsanis et al. (1990) found a similar pattern of responding among the first-degree relatives of first-episode psychotic patients. Although the relative group’s scores were significantly higher than the controls’ for the physical anhedonia and social anhedonia scales, their scores on the PAS were significantly lower relative to the controls. Using a different measure of psychosis-proneness, Claridge and coworkers (Claridge et al., 1983; Claridge and Beech, 1996) have shown that the relatives of schizophrenics score significantly lower than the relatives of neurotic patients on the STA scale (STQ: schizotypal personality, Claridge and Broks, 1984). In contrast to these four previous studies, which have failed to show that the relatives of schizophrenics and psychotic patients score higher on psychosis-proneness scales (which measure ‘positive’ schizotypal traits), a fifth recent study by Kremen et al. (1998) found that the biological relatives of schizophrenics endorse significantly more cognitive-perceptual schizotypal traits on the SPQ than controls without a family history of schizophrenia. These positive findings for the SPQ thus conflict with previous failures to demonstrate higher scores on the PAS among relatives of schizophrenics. Although the relatives of schizophrenics endorsed more items on the interpersonal deficits factor (which measures ‘negative’ traits of schizotypy) than the controls, this difference did not reach statistical significance. This finding also conflicts with previous findings for negative schizotypal traits. Finally, group differences reached a trend level of significance for the disorganization factor of the SPQ. Thus, there is a discrepancy in how relatives of schizophrenic and psychotic patients score on measures of schizotypy. Although scales of psychosisproneness indicate that they score higher on negative features (specifically, physical anhedonia), the study by Kremen et al. (1998), which is the only study to use the SPQ, finds that they score significantly higher on positive, cognitive-perceptual features. It is possible that the SPQ is better able to
detect positive schizotypal features in the relatives of schizophrenics than other measures of psychosis-proneness. The goal of the present study is to pursue further and extend this recent finding of Kremen et al. (1998). First, it was predicted that relatives of individuals with schizophrenia spectrum disorders (SSDs) will score higher on the cognitive-perceptual factor of the SPQ than individuals without a family history of schizophrenia. Second, no previous study has controlled for alcohol/substance usage, which may inflate scores for traits like unusual perceptual experiences. In the present study, the relatives of individuals with SSDs were compared with a second control group of individuals with a family history of alcoholism or drug use, a group who may artifactually endorse cognitive-perceptual items. It was predicted that relatives of individuals with SSDs will also score higher on the cognitiveperceptual factor of the SPQ than the psychiatric control group of individuals with a family history of alcoholism or drug use.
2. Method 2.1. Subjects An unselected community sample of participants was recruited from five temporary employment agencies in Los Angeles to take part in a larger study on brain mechanisms and schizotypy. Unlike previous studies, in which the participants were aware that they were recruited based on their family psychiatric history, the participants in the present study were not recruited on this basis. Participants were told that the purpose of the study was to learn more about the biological basis of personality and problem behaviors, including crime in an unselected population. They were also informed that they would be questioned about their early family experiences and undergo brain imaging and psychophysiological testing. Written informed consent was obtained from all participants. The total sample consisted of 102 participants who were subdivided into 13 individuals with a family history of SSD, 51 participants without a family history of SSD or alcoholism/
P.S. Yaralian et al. / Schizophrenia Research 46 (2000) 57–63
drug use, and a psychiatric control group of 38 participants with a family history of alcoholism/ drug use. Socio-economic status (SES) for mothers and fathers of the participants was rated according to the Hollingshead Index (Hollingshead, 1975). A general parental SES measure was computed by taking the average of the mothers’ and fathers’ ratings. One-way analyses of variance (ANOVAs) indicated that the three participant groups did not differ in parental SES (F=0.3, P<0.73) or age (F=0.225, P<0.80). x2 analyses revealed that the three groups did not differ significantly on ethnic composition ( x2=4.17, P<0.12) or gender ( x2=0.345, P<0.84). Demographic characteristics of the sample are summarized in Table 1. 2.2. Schizotypal personality Participants were administered the SPQ, a 74-item self-report scale modeled on DSM-III-R criteria (Raine, 1991). The SPQ includes nine subscales that reflect the nine traits of schizotypal personality disorder listed in DSM-III-R (APA, 1987). On the basis of previous research ( Raine et al., 1994), the SPQ was subdivided into three syndromes or factors: cognitive-perceptual deficits Table 1 Age, gender, ethnicity, and SES assessed by Hollingshead Index for participants with a family history of SSD, participants without a family history of SSD, and participants with a family history of alcoholism/drug use. Standard deviations are given in parentheses Groups
Age Gender males females Race white non-white SES
Family history+ N=13
Family history− N=51
Alcohol/ drug use N=38
29.92 (7.33)
31.33 (6.75)
31.25 (6.99)
12 1
44 7
34 4
10 3 37.2 (13.7)
23 38 39.8 (13.6)
17 21 38.2 (10.5)
59
(consisting of items related to ideas of reference, magical thinking, unusual perceptual experiences, and paranoid ideation), interpersonal deficits (social anxiety, no close friends, blunted affect, paranoid ideation), and disorganization (odd behavior, odd speech). Reliability and validity data are reported in Raine (1991). 2.3. Family history of psychiatric illness The participants’ family histories of psychiatric illness were assessed via the family history-research diagnostic criteria interview (Andreasen et al., 1977). Based on RDC interview guidelines, the following disorders in family members were assessed: schizophrenia, schizotypal personality disorder, alcoholism, drug use, and antisocial personality disorder. Interviews of the participants were conducted by research assistants who had undergone a standardized training and quality assurance program for diagnostic assessment ( Ventura et al., 1998).
3. Results Total SPQ scores and scores for each of the three SPQ factors were compared first between the participants with a family history of SSD and the normal controls, and second, between the individuals with a family history of SSDs and the psychiatric control group of individuals with family histories of alcoholism or drug use. Means, standard deviations, results of one-way ANOVA of group comparisons, and effect sizes calculated as Cohen’s d (Cohen, 1988) are given in Table 2. One-way ANOVA revealed a significant overall group effect for the cognitive-perceptual factor (F=4.7, P<0.011). Post-hoc testing revealed that individuals with a family history of SSD scored significantly higher on this factor than both individuals without a family history of SSD (t= 3.12, P<0.003) and the individuals with a family history of alcoholism or drug use (t=2.38, P<0.012). There were no significant group effects for total SPQ scores (F=1.52, P<0.22), scores for the disorganization factor (F=1.28, P<0.28), or for the interpersonal deficits factor (F=0.06, P<0.95).
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P.S. Yaralian et al. / Schizophrenia Research 46 (2000) 57–63
Table 2 Means, standard deviations (in parentheses), effect sizes d, F and P values for one-way ANOVAs for group comparisons on SPQ total scores and scores for three factors for participants with a family history of SSD (FH+), participants without a family history of SSD ( FH−), and participants with a family history of alcoholism/drug use (A/D) SPQ factors
Groups
F
P
Group comparisons
d
Family history+
Family history−
Alcohol/drug
Cognitive-perceptual
16.69 (8.35)
9.86 (6.68)
10.79 (7.49)
4.69
0.011
FH+ versus FH− FH+ versus A/D
0.95 0.82
Interpersonal deficits
10.08 (7.27)
9.58 (6.26)
10.03 (7.47)
0.057
0.945
FH+ versus FH− FH+ versus A/D
0.07 0.001
Disorganization
7.46 (4.56)
5.36 (4.29)
6.28 (4.71)
1.28
0.284
FH+ versus FH− FH+ versus A/D
0.47 0.26
Total SPQ
32.83 (16.04)
24.29 (13.42)
27.05 (17.20)
1.55
0.217
FH+ versus FH− FH+ versus A/D
0.56 0.38
Scores on each of the nine individual subscales of the SPQ were also examined. Separate comparisons were made between the family-history positive group and each of the two control groups. Oneway ANOVA revealed significant overall groups effects for the ‘ideas of reference’ (F=3.61, P<0.03) and ‘unusual perceptual experiences’ subscales (F=5.23, P<0.01). A trend was observed for the ‘paranoid ideation’ subscale (F=2.75, P<0.07). Post-hoc testing revealed that the familyhistory positive group scored significantly higher on the ‘ideas of reference’ subscale (M=5.0) compared with individuals without a family history of SSD (M=2.9) (t=2.75, P=0.01). There were no significant differences between the family-history positive group and the psychiatric control group (M=3.67) (t=1.49, P<0.17), although the familyhistory positive group scored higher. For the ‘unusual perceptual experiences’ subscale, post-hoc testing revealed that the family-history positive group scored significantly higher (M=4.38) than the group without a family history of SSD (M= 2.37) (t=2.77, P<0.01). There were no significant differences between the family-history positive group and the psychiatric control group (M=2.03) (t=2.86, P<0.49), although the family-history positive group again scored higher. Although univariate ANOVA revealed only a trend for the ‘paranoid ideation’ subscale, post-hoc testing revealed a significant difference between the familyhistory positive group (M=3.92) and the group
without a family history of SSD (M=2.33) (t= 2.37, P=0.021) and a trend level difference between the family-history positive group and the psychiatric control group (M=2.58) (t=1.84, P= 0.06). There were no significant differences between the groups for the remaining subscales.
4. Discussion The results of this study support the findings of Kremen et al. (1998) in that both studies find elevated scores among the first-degree relatives of individuals with SSDs on the cognitive-perceptual factor of the SPQ. Furthermore, the components of the cognitive-perceptual factor that differentiate the family-history positive group from the normal controls in the present study are the ‘ideas of reference’ and ‘unusual perceptual experiences’ subscales. There is a discrepancy, however, between the present study’s positive findings for the ‘unusual perceptual experiences’ subscale and the Kremen et al. (1998) failure to show group differences on this same subscale. The present study and that of Kremen et al. (1998) do not support findings from previous studies using psychosis-proneness measures (e.g. PAS) that have failed to demonstrate that the relatives of schizophrenics and psychotic patients score higher on measures of positive schizotypy (Claridge et al., 1983; Katsanis et al., 1990;
P.S. Yaralian et al. / Schizophrenia Research 46 (2000) 57–63
Clementz et al., 1991; Claridge and Beech, 1996). The two studies that have found significant effects used the SPQ in contrast to the various other measures of psychosis-proneness used in the other studies (e.g. PAS, STA). It is possible that the SPQ is a more sensitive instrument for detecting differences in the relatives of schizophrenics and psychotic patients. The superior findings with the SPQ may result from the greater sampling validity of the SPQ relative to other psychosis-proneness measures, in that the SPQ assesses four positive features of SPD: ideas of reference, magical thinking, unusual perceptual experiences, and suspiciousness. In both the present study and that of Kremen et al. (1998), significant group effects were found for the ‘ideas of reference’ subscale. Additionally, Kremen et al. (1998) found significant effects for the ‘suspiciousness’ or ‘paranoid ideation’ subscale, whereas the present study found a trend level of significance for this subscale. Referential thinking and suspiciousness are features of schizotypy that are not assessed by the PAS. Consequently, the fact that the SPQ does assess these features is a possible reason for the discrepancy between those studies that do and those that do not find group differences for positive schizotypy. An alternative explanation for the discrepancy that cannot be completely discounted is psychological defensiveness. It has been proposed that defensive responding on psychosis-proneness measures of positive schizotypal traits may lower scores among those with a family history of psychiatric illness (Claridge et al., 1983; Katsanis et al., 1990). Because the primary aim of these studies has been focused on schizophrenia and psychosis, it is possible that the nature of the studies sensitized relatives of psychotic patients to their risk for psychosis, made them more defensive, and produced artificially lower psychosis-proneness scores. However, the results of the two studies that have used the SPQ rather than other psychosis-proneness measures, such as the PAS, to assess schizotypal features do not support the defensiveness hypothesis raised by other researchers, according to which the individuals with family histories of SSDs would have endorsed fewer cognitiveperceptual items on the SPQ. Yet, in the study by Kremen et al. (1998), positive effects were observed
61
for two subscales of the cognitive-perceptual factor. Furthermore, the present study also finds elevated Cognitive-perceptual scores, including significantly elevated scores on the ‘unusual perceptual experiences’ subscale, the content of which closely parallels the items found on the PAS, which previously failed to discriminate the relatives of schizophrenics from normal controls. It is possible that the SPQ may invoke less defensiveness by virtue of using less subtle wording to assess bizarre, psychotic-like traits than the PAS. Relatives of individuals with SSDs may have been less inclined to adopt a defensive stance when endorsing positive, but relatively more ‘normal’ items on the SPQ compared with the PAS. However, the defensiveness hypothesis cannot be ruled out completely given the discrepancy between the present study’s positive effects for the ‘unusual perceptual experiences’ subscale and the Kremen et al. (1998) failure to detect this effect. Our ability to detect differences on this subscale may have resulted from a lack of defensiveness on the part of the participants in this study. Unlike all previous investigations of first-degree relatives of schizophrenics and psychotic patients, including the one by Kremen et al. (1998) in which the relatives of schizophrenics were recruited based on their family psychiatric history, the primary aim of this study was not focused on schizophrenia or psychosis. As such, the present investigation represents the first attempt, to our knowledge, to examine scores on the SPQ among a sample who were not recruited specifically based on their familial psychiatric status. Although we believe that defensiveness cannot fully account for previous failures to obtain group differences on positive schizotypal features, our ability to detect differences on the ‘unusual perceptual experiences’ subscale among a sample who were not recruited specifically based on their familial psychiatric history is consistent with, but does not prove, that defensiveness may have influenced responding in previous studies. There were no significant differences observed between the groups on the interpersonal deficits factor. Null findings for this factor may partly be due to a methodological limitation of the FH-RDC method. The interview questions to define schizophrenia primarily focus on unusual perceptual experiences, paranoid ideation, odd speech and
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odd behavior, and do not prompt for the more negative symptoms, including blunted affect, no close friends, or social anxiety. This raises the possibility that the present investigation was unable to detect those individuals who have a family history of schizophrenia-spectrum disorders characterized mostly by negative symptoms, resulting in null findings for the interpersonal deficits factor. In support of this possibility, Kremen et al. (1998), who used a different technique for identifying the relatives of schizophrenics, did find a trend for interpersonal deficits and a medium effect size of 0.41. Because other studies have found effects for the negative features of psychosis-proneness, the possibility that negative features of schizotypy do characterize individuals with a family history of SSD cannot be discounted. Although the present investigation did not obtain significant effects for the disorganization factor of the SPQ, a medium effect size (0.47) in the predicted direction was obtained. This effect size is similar to the one that Kremen et al. (1998) obtained for their overall model for the disorganization factor (0.50). Thus, null results for this factor should be interpreted cautiously, as the failure to obtain statistical significance may have resulted from a lack of statistical power. Future studies with larger groups of responders are needed to resolve whether individuals with family histories of SSDs differ from controls on the disorganization factor of the SPQ. The inclusion of a psychiatric control group of individuals with a family history of alcoholism or drug use in the present study provides initial evidence for the diagnostic specificity of elevated cognitive-perceptual scores on the SPQ. Our finding, that individuals with a family history of SSDs score higher on the cognitive-perceptual factor than a psychiatric control group who may artifactually endorse such symptoms, further indicates that elevated cognitive-perceptual deficits are a characteristic of those who are constitutionally at risk for developing SSDs.
Acknowledgements This study was supported by grants to the first author from NIMH (National Research Service
Award 1 F31 MH11761-01) and to the second author from NIMH (Research Scientist Development Award K02 MH01114-01, Independent Scientist Award K02 MH01114-01 and 5 RO3 MH50940-02), and from the Wacker Foundation.
References American Psychiatric Association, 1987. Diagnostic and Statistical Manual of Mental Disorders. third revised ed., American Psychiatric Association, Washington, DC. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders. fourth ed., American Psychiatric Association, Washington, DC. Andreasen, N.C., Endicott, J., Spitzer, R.L., Winokur, G., 1977. The family history method using diagnostic criteria. Archives of General Psychiatry 34, 1229–1235. Chapman, L.J., Chapman, J.P., Raulin, M.L., 1976. Scales for physical and social anhedonia. Journal of Abnormal Psychology 85, 374–382. Chapman, L.J., Chapman, J.P., Raulin, M.L., 1978. Bodyimage aberration in schizophrenia. Journal of Abnormal Psychology 87, 399–407. Chapman, L.J., Chapman, J.P., Kwapil, T.R., 1995. Scales for the measurement of schizotypy. In: Raine, A., Lencz, T., Mednick, S.A. ( Eds.), Schizotypal Personality. Cambridge University Press, New York. Claridge, G., Beech, A., 1996. Schizotypy and lateralised negative priming in schizophrenics’ and neurotics’ relatives. Personality and Individual Differences 20 (2), 193–199. Claridge, G., Broks, P., 1984. Schizotypy and hemisphere function-I. Theoretical considerations and the measurement of schizotypy. Personality and Individual Differences 5, 633–648. Claridge, G., Robinson, D.L., Birchall, P., 1983. Characteristics of schizophrenics’ and neurotics’ relatives. Personality and Individual Differences 4, 651–664. Clementz, B.A., Grove, W.M., Katsanis, J., Iacono, W.G., 1991. Psychometric detection of schizotypy: perceptual aberration and physical anhedonia in relatives of schizophrenics. Journal of Abnormal Psychology 100 (4), 607–612. Cohen, J., 1988. Statistical Power Analysis for the Behavioral Sciences. second ed., Lawrence Erlbaum, Hillsdale, NJ. Eckblad, M., Chapman, L.J., 1983. Magical ideation as an indicator of schizotypy. Journal of Consulting and Clinical Psychology 51, 215–225. Hollingshead, A.B., 1975. Four Factor Index of Social Status. Yale University, New Haven, CT. Katsanis, J., Iacono, W.G., Beiser, M., 1990. Anhedonia and perceptual aberration in first-episode psychotic patients and their relatives. Journal of Abnormal Psychology 99 (2), 202–206. Kremen, W.S., Faraone, S.V., Toomey, R., Seidman, L.J.,
P.S. Yaralian et al. / Schizophrenia Research 46 (2000) 57–63 Tsuang, M.T., 1998. Sex differences in self-reported schizotypal traits in relatives of schizophrenia probands. Schizophrenia Research 34, (1–2), 27–37. Raine, A., 1991. The SPQ: A scale for the assessment of schizotypal personality based on DSM-III-R criteria. Schizophrenia Bulletin 17, 555–564. Raine, A., Reynolds, C., Lencz, T., Scerbo, A., Triphon, N., Kim, D., 1994. Cognitive-perceptual, interpersonal, and dis-
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organized features of schizotypal personality. Schizophrenia Bulletin 20, 191–201. Raine, A., Lencz, T., Mednick, S.A., 1995. Schizotypal Personality. Cambridge University Press, New York. Ventura, J., Liberman, R.P., Green, M.F., Shaner, A., Mintz, J., 1998. Training and quality assurance with Structured Clinical Interview for DSM-IV (SCID-I/P). Psychiatry Research 79 (2), 163–173.
Elevated levels of cognitive-perceptual deficits in individuals with a family history of schizophrenia spectrum disorders Pauline S. Yaralian a, Adrian Raine a, *, Todd Lencz b, Jill M. Hooley c, Susan E. Bihrle a, Shari Mills a, Joseph Ventura d a Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, USA b Department of Research, Hillside Hospital (North Shore Long Island Jewish Health System), 75-59 263rd St., Glen Oaks, NY 11004, USA c Department of Psychology, Harvard University, Boston, MA 02138, USA d UCLA Department of Psychiatry and Biobehavioral Sciences, Los Angeles, CA 90095–6968, USA Received 14 July 1999; accepted 30 November 1999
Abstract This study finds that the relatives of schizophrenics have elevated scores on the cognitiveperceptual factor of the schizotypal personality questionnaire (SPQ), particularly for the ‘unusual perceptual experiences’ and ‘ideas of reference’ subscales. These results support recent findings by Kremen et al. (1998) and suggest that previous failures to demonstrate elevated scores on ‘positive’ symptoms of schizotypy may be a function of instrumentation. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Cognitive-perceptual; Schizophrenia; Schizotypal personality disorder; SPQ
1. Introduction Research in the area of individual differences in schizotypy using self-report techniques has taken two approaches. First, measures of ‘psychosis proneness’ have been developed to assess some of the positive [magical ideation, Eckblad and Chapman, 1983; perceptual aberration scale (PAS), Chapman et al., 1978] and negative features of schizotypy (physical anhedonia scale, Chapman et al., 1976; social anhedonia scale, Chapman et al., 1976). The second approach is based on the conceptualization of schizotypal personality disorder (SPD) found in the DSM-III-R (APA, 1987) and DSM-IV (APA, 1994) and
* Corresponding author.
includes nine features. The schizotypal personality questionnaire (SPQ, Raine, 1991) is modeled on DSM-III-R criteria for SPD and consists of subscales for all nine schizotypal features. Research on the psychosis-proneness scales and the SPQ has amassed a significant body of psychometric data indicating that they are useful indicators of psychosis-proneness (Chapman et al., 1995; Raine et al., 1995). However, attempts to validate these scales against first-degree relatives of schizophrenics and psychotic patients have produced conflicting findings. Clementz et al. (1991) administered psychosis-proneness measures to the firstdegree relatives of schizophrenics. They found that the first-degree relatives of schizophrenics scored higher on the physical anhedonia scale relative to controls who lacked psychotic disorders both in themselves and their first-degree relatives.
0920-9964/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0 9 2 0 -9 9 6 4 ( 9 9 ) 0 0 23 9 - X
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However, their scores on the PAS, which taps some of the more ‘positive’ features of psychosisproneness, were significantly lower than the controls. Katsanis et al. (1990) found a similar pattern of responding among the first-degree relatives of first-episode psychotic patients. Although the relative group’s scores were significantly higher than the controls’ for the physical anhedonia and social anhedonia scales, their scores on the PAS were significantly lower relative to the controls. Using a different measure of psychosis-proneness, Claridge and coworkers (Claridge et al., 1983; Claridge and Beech, 1996) have shown that the relatives of schizophrenics score significantly lower than the relatives of neurotic patients on the STA scale (STQ: schizotypal personality, Claridge and Broks, 1984). In contrast to these four previous studies, which have failed to show that the relatives of schizophrenics and psychotic patients score higher on psychosis-proneness scales (which measure ‘positive’ schizotypal traits), a fifth recent study by Kremen et al. (1998) found that the biological relatives of schizophrenics endorse significantly more cognitive-perceptual schizotypal traits on the SPQ than controls without a family history of schizophrenia. These positive findings for the SPQ thus conflict with previous failures to demonstrate higher scores on the PAS among relatives of schizophrenics. Although the relatives of schizophrenics endorsed more items on the interpersonal deficits factor (which measures ‘negative’ traits of schizotypy) than the controls, this difference did not reach statistical significance. This finding also conflicts with previous findings for negative schizotypal traits. Finally, group differences reached a trend level of significance for the disorganization factor of the SPQ. Thus, there is a discrepancy in how relatives of schizophrenic and psychotic patients score on measures of schizotypy. Although scales of psychosisproneness indicate that they score higher on negative features (specifically, physical anhedonia), the study by Kremen et al. (1998), which is the only study to use the SPQ, finds that they score significantly higher on positive, cognitive-perceptual features. It is possible that the SPQ is better able to
detect positive schizotypal features in the relatives of schizophrenics than other measures of psychosis-proneness. The goal of the present study is to pursue further and extend this recent finding of Kremen et al. (1998). First, it was predicted that relatives of individuals with schizophrenia spectrum disorders (SSDs) will score higher on the cognitive-perceptual factor of the SPQ than individuals without a family history of schizophrenia. Second, no previous study has controlled for alcohol/substance usage, which may inflate scores for traits like unusual perceptual experiences. In the present study, the relatives of individuals with SSDs were compared with a second control group of individuals with a family history of alcoholism or drug use, a group who may artifactually endorse cognitive-perceptual items. It was predicted that relatives of individuals with SSDs will also score higher on the cognitiveperceptual factor of the SPQ than the psychiatric control group of individuals with a family history of alcoholism or drug use.
2. Method 2.1. Subjects An unselected community sample of participants was recruited from five temporary employment agencies in Los Angeles to take part in a larger study on brain mechanisms and schizotypy. Unlike previous studies, in which the participants were aware that they were recruited based on their family psychiatric history, the participants in the present study were not recruited on this basis. Participants were told that the purpose of the study was to learn more about the biological basis of personality and problem behaviors, including crime in an unselected population. They were also informed that they would be questioned about their early family experiences and undergo brain imaging and psychophysiological testing. Written informed consent was obtained from all participants. The total sample consisted of 102 participants who were subdivided into 13 individuals with a family history of SSD, 51 participants without a family history of SSD or alcoholism/
P.S. Yaralian et al. / Schizophrenia Research 46 (2000) 57–63
drug use, and a psychiatric control group of 38 participants with a family history of alcoholism/ drug use. Socio-economic status (SES) for mothers and fathers of the participants was rated according to the Hollingshead Index (Hollingshead, 1975). A general parental SES measure was computed by taking the average of the mothers’ and fathers’ ratings. One-way analyses of variance (ANOVAs) indicated that the three participant groups did not differ in parental SES (F=0.3, P<0.73) or age (F=0.225, P<0.80). x2 analyses revealed that the three groups did not differ significantly on ethnic composition ( x2=4.17, P<0.12) or gender ( x2=0.345, P<0.84). Demographic characteristics of the sample are summarized in Table 1. 2.2. Schizotypal personality Participants were administered the SPQ, a 74-item self-report scale modeled on DSM-III-R criteria (Raine, 1991). The SPQ includes nine subscales that reflect the nine traits of schizotypal personality disorder listed in DSM-III-R (APA, 1987). On the basis of previous research ( Raine et al., 1994), the SPQ was subdivided into three syndromes or factors: cognitive-perceptual deficits Table 1 Age, gender, ethnicity, and SES assessed by Hollingshead Index for participants with a family history of SSD, participants without a family history of SSD, and participants with a family history of alcoholism/drug use. Standard deviations are given in parentheses Groups
Age Gender males females Race white non-white SES
Family history+ N=13
Family history− N=51
Alcohol/ drug use N=38
29.92 (7.33)
31.33 (6.75)
31.25 (6.99)
12 1
44 7
34 4
10 3 37.2 (13.7)
23 38 39.8 (13.6)
17 21 38.2 (10.5)
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(consisting of items related to ideas of reference, magical thinking, unusual perceptual experiences, and paranoid ideation), interpersonal deficits (social anxiety, no close friends, blunted affect, paranoid ideation), and disorganization (odd behavior, odd speech). Reliability and validity data are reported in Raine (1991). 2.3. Family history of psychiatric illness The participants’ family histories of psychiatric illness were assessed via the family history-research diagnostic criteria interview (Andreasen et al., 1977). Based on RDC interview guidelines, the following disorders in family members were assessed: schizophrenia, schizotypal personality disorder, alcoholism, drug use, and antisocial personality disorder. Interviews of the participants were conducted by research assistants who had undergone a standardized training and quality assurance program for diagnostic assessment ( Ventura et al., 1998).
3. Results Total SPQ scores and scores for each of the three SPQ factors were compared first between the participants with a family history of SSD and the normal controls, and second, between the individuals with a family history of SSDs and the psychiatric control group of individuals with family histories of alcoholism or drug use. Means, standard deviations, results of one-way ANOVA of group comparisons, and effect sizes calculated as Cohen’s d (Cohen, 1988) are given in Table 2. One-way ANOVA revealed a significant overall group effect for the cognitive-perceptual factor (F=4.7, P<0.011). Post-hoc testing revealed that individuals with a family history of SSD scored significantly higher on this factor than both individuals without a family history of SSD (t= 3.12, P<0.003) and the individuals with a family history of alcoholism or drug use (t=2.38, P<0.012). There were no significant group effects for total SPQ scores (F=1.52, P<0.22), scores for the disorganization factor (F=1.28, P<0.28), or for the interpersonal deficits factor (F=0.06, P<0.95).
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Table 2 Means, standard deviations (in parentheses), effect sizes d, F and P values for one-way ANOVAs for group comparisons on SPQ total scores and scores for three factors for participants with a family history of SSD (FH+), participants without a family history of SSD ( FH−), and participants with a family history of alcoholism/drug use (A/D) SPQ factors
Groups
F
P
Group comparisons
d
Family history+
Family history−
Alcohol/drug
Cognitive-perceptual
16.69 (8.35)
9.86 (6.68)
10.79 (7.49)
4.69
0.011
FH+ versus FH− FH+ versus A/D
0.95 0.82
Interpersonal deficits
10.08 (7.27)
9.58 (6.26)
10.03 (7.47)
0.057
0.945
FH+ versus FH− FH+ versus A/D
0.07 0.001
Disorganization
7.46 (4.56)
5.36 (4.29)
6.28 (4.71)
1.28
0.284
FH+ versus FH− FH+ versus A/D
0.47 0.26
Total SPQ
32.83 (16.04)
24.29 (13.42)
27.05 (17.20)
1.55
0.217
FH+ versus FH− FH+ versus A/D
0.56 0.38
Scores on each of the nine individual subscales of the SPQ were also examined. Separate comparisons were made between the family-history positive group and each of the two control groups. Oneway ANOVA revealed significant overall groups effects for the ‘ideas of reference’ (F=3.61, P<0.03) and ‘unusual perceptual experiences’ subscales (F=5.23, P<0.01). A trend was observed for the ‘paranoid ideation’ subscale (F=2.75, P<0.07). Post-hoc testing revealed that the familyhistory positive group scored significantly higher on the ‘ideas of reference’ subscale (M=5.0) compared with individuals without a family history of SSD (M=2.9) (t=2.75, P=0.01). There were no significant differences between the family-history positive group and the psychiatric control group (M=3.67) (t=1.49, P<0.17), although the familyhistory positive group scored higher. For the ‘unusual perceptual experiences’ subscale, post-hoc testing revealed that the family-history positive group scored significantly higher (M=4.38) than the group without a family history of SSD (M= 2.37) (t=2.77, P<0.01). There were no significant differences between the family-history positive group and the psychiatric control group (M=2.03) (t=2.86, P<0.49), although the family-history positive group again scored higher. Although univariate ANOVA revealed only a trend for the ‘paranoid ideation’ subscale, post-hoc testing revealed a significant difference between the familyhistory positive group (M=3.92) and the group
without a family history of SSD (M=2.33) (t= 2.37, P=0.021) and a trend level difference between the family-history positive group and the psychiatric control group (M=2.58) (t=1.84, P= 0.06). There were no significant differences between the groups for the remaining subscales.
4. Discussion The results of this study support the findings of Kremen et al. (1998) in that both studies find elevated scores among the first-degree relatives of individuals with SSDs on the cognitive-perceptual factor of the SPQ. Furthermore, the components of the cognitive-perceptual factor that differentiate the family-history positive group from the normal controls in the present study are the ‘ideas of reference’ and ‘unusual perceptual experiences’ subscales. There is a discrepancy, however, between the present study’s positive findings for the ‘unusual perceptual experiences’ subscale and the Kremen et al. (1998) failure to show group differences on this same subscale. The present study and that of Kremen et al. (1998) do not support findings from previous studies using psychosis-proneness measures (e.g. PAS) that have failed to demonstrate that the relatives of schizophrenics and psychotic patients score higher on measures of positive schizotypy (Claridge et al., 1983; Katsanis et al., 1990;
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Clementz et al., 1991; Claridge and Beech, 1996). The two studies that have found significant effects used the SPQ in contrast to the various other measures of psychosis-proneness used in the other studies (e.g. PAS, STA). It is possible that the SPQ is a more sensitive instrument for detecting differences in the relatives of schizophrenics and psychotic patients. The superior findings with the SPQ may result from the greater sampling validity of the SPQ relative to other psychosis-proneness measures, in that the SPQ assesses four positive features of SPD: ideas of reference, magical thinking, unusual perceptual experiences, and suspiciousness. In both the present study and that of Kremen et al. (1998), significant group effects were found for the ‘ideas of reference’ subscale. Additionally, Kremen et al. (1998) found significant effects for the ‘suspiciousness’ or ‘paranoid ideation’ subscale, whereas the present study found a trend level of significance for this subscale. Referential thinking and suspiciousness are features of schizotypy that are not assessed by the PAS. Consequently, the fact that the SPQ does assess these features is a possible reason for the discrepancy between those studies that do and those that do not find group differences for positive schizotypy. An alternative explanation for the discrepancy that cannot be completely discounted is psychological defensiveness. It has been proposed that defensive responding on psychosis-proneness measures of positive schizotypal traits may lower scores among those with a family history of psychiatric illness (Claridge et al., 1983; Katsanis et al., 1990). Because the primary aim of these studies has been focused on schizophrenia and psychosis, it is possible that the nature of the studies sensitized relatives of psychotic patients to their risk for psychosis, made them more defensive, and produced artificially lower psychosis-proneness scores. However, the results of the two studies that have used the SPQ rather than other psychosis-proneness measures, such as the PAS, to assess schizotypal features do not support the defensiveness hypothesis raised by other researchers, according to which the individuals with family histories of SSDs would have endorsed fewer cognitiveperceptual items on the SPQ. Yet, in the study by Kremen et al. (1998), positive effects were observed
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for two subscales of the cognitive-perceptual factor. Furthermore, the present study also finds elevated Cognitive-perceptual scores, including significantly elevated scores on the ‘unusual perceptual experiences’ subscale, the content of which closely parallels the items found on the PAS, which previously failed to discriminate the relatives of schizophrenics from normal controls. It is possible that the SPQ may invoke less defensiveness by virtue of using less subtle wording to assess bizarre, psychotic-like traits than the PAS. Relatives of individuals with SSDs may have been less inclined to adopt a defensive stance when endorsing positive, but relatively more ‘normal’ items on the SPQ compared with the PAS. However, the defensiveness hypothesis cannot be ruled out completely given the discrepancy between the present study’s positive effects for the ‘unusual perceptual experiences’ subscale and the Kremen et al. (1998) failure to detect this effect. Our ability to detect differences on this subscale may have resulted from a lack of defensiveness on the part of the participants in this study. Unlike all previous investigations of first-degree relatives of schizophrenics and psychotic patients, including the one by Kremen et al. (1998) in which the relatives of schizophrenics were recruited based on their family psychiatric history, the primary aim of this study was not focused on schizophrenia or psychosis. As such, the present investigation represents the first attempt, to our knowledge, to examine scores on the SPQ among a sample who were not recruited specifically based on their familial psychiatric status. Although we believe that defensiveness cannot fully account for previous failures to obtain group differences on positive schizotypal features, our ability to detect differences on the ‘unusual perceptual experiences’ subscale among a sample who were not recruited specifically based on their familial psychiatric history is consistent with, but does not prove, that defensiveness may have influenced responding in previous studies. There were no significant differences observed between the groups on the interpersonal deficits factor. Null findings for this factor may partly be due to a methodological limitation of the FH-RDC method. The interview questions to define schizophrenia primarily focus on unusual perceptual experiences, paranoid ideation, odd speech and
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odd behavior, and do not prompt for the more negative symptoms, including blunted affect, no close friends, or social anxiety. This raises the possibility that the present investigation was unable to detect those individuals who have a family history of schizophrenia-spectrum disorders characterized mostly by negative symptoms, resulting in null findings for the interpersonal deficits factor. In support of this possibility, Kremen et al. (1998), who used a different technique for identifying the relatives of schizophrenics, did find a trend for interpersonal deficits and a medium effect size of 0.41. Because other studies have found effects for the negative features of psychosis-proneness, the possibility that negative features of schizotypy do characterize individuals with a family history of SSD cannot be discounted. Although the present investigation did not obtain significant effects for the disorganization factor of the SPQ, a medium effect size (0.47) in the predicted direction was obtained. This effect size is similar to the one that Kremen et al. (1998) obtained for their overall model for the disorganization factor (0.50). Thus, null results for this factor should be interpreted cautiously, as the failure to obtain statistical significance may have resulted from a lack of statistical power. Future studies with larger groups of responders are needed to resolve whether individuals with family histories of SSDs differ from controls on the disorganization factor of the SPQ. The inclusion of a psychiatric control group of individuals with a family history of alcoholism or drug use in the present study provides initial evidence for the diagnostic specificity of elevated cognitive-perceptual scores on the SPQ. Our finding, that individuals with a family history of SSDs score higher on the cognitive-perceptual factor than a psychiatric control group who may artifactually endorse such symptoms, further indicates that elevated cognitive-perceptual deficits are a characteristic of those who are constitutionally at risk for developing SSDs.
Acknowledgements This study was supported by grants to the first author from NIMH (National Research Service
Award 1 F31 MH11761-01) and to the second author from NIMH (Research Scientist Development Award K02 MH01114-01, Independent Scientist Award K02 MH01114-01 and 5 RO3 MH50940-02), and from the Wacker Foundation.
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