Scandinavian Journal of Psychology, 2010, 51, 68–74 DOI: 10.1111/j.1467-9450.2009.00730.x

Personality and Social Sciences Premorbid personality indicators of schizophrenia-related psychosis in a hypothetically psychosis-prone college sample

P. KEVIN BOLINSKEY 1 and IRVING I. GOTTESMAN 2 1Indiana State University, USA 2University of Minnesota, USA

Bolinskey, P. K. & Gottesman, I. I. (2010). Premorbid personality indicators of schizophrenia-related psychosis in a hypothetically psychosis-prone college sample. Scandinavian Journal of Psychology, 51, 68–74. Research into psychosis proneness has established the Chapman Psychosis Proneness Scales (CPPS), certain personality disorders, certain response patterns on the MMPI-2, and social withdrawal as being valid indicators of liability. The current study extends our understanding of premorbid indicators of schizophrenia-related psychosis (SRP) by examining whether individuals identified as hypothetically psychosis prone (HPP) by virtue of their CPPS scores also show differences on other premorbid indicators of SRP. Results indicate that HPP individuals evidence more deviancy in the schizophrenic direction. By providing additional construct validity for the CPPS and other endophenotypic indicators of premorbid processes, strategies for understanding the development of SRP are enhanced. Key words: Schizotypy, MMPI-2, PDQ-4, endophenotypes, psychometric high risk, Chapman scales. P. Kevin Bolinskey, Department of Psychology, B-214 Root Hall, Indiana State University, Terre Haute, IN 47809, USA . E-mail: [email protected]

INTRODUCTION Chapman Psychosis Proneness Scales Results from decades of adoption, twin, and family studies have Among the measures found to be effective in identifying psychosis demonstrated that liability to schizophrenia is genetically prone individuals are the CPPS, which include the Revised mediated, although expression of the disorder is mediated by non- PhysicalAnhedoniaScale( PhyAnh ;Chapman,Chapman&Raulin, genetic factors. Among the key attributes of a multifactorial/ 1976), the Perceptual Aberration Scale ( PerAb ; Chapman, threshold model of schizophrenia development is the assumption Chapman & Raulin, 1978), the Magical Ideation Scale ( MagId ; that the majority of individuals with increased liability to Eckblad & Chapman, 1983), and the Revised Social Anhedonia schizophrenia will not decompensate into psychosis, although Scale ( SocAnh ; Eckblad, Chapman, Chapman & Mishlove, 1982). they may experience schizotypal symptoms (Lenzenweger, Studies have found higher incidence of schizophrenia-related 2006) or neurobehavioral deficits (Cornblatt, Obuchowski, psychosis among individuals identified as psychosis prone on the Roberts, Pollack & Erlenmeyer-Kimling, 1999). This model basis of CPPS scores relative to comparison groups at ten-year also suggests that as risk factors for the disorder accumulate so follow-up (Chapman, Chapman, Kwapil, Eckblad & Zinser, too does psychiatric deviance. Thus, researchers consider the 1994; Kwapil, 1998), as well as more frequent and severe psychotic- presence of endophenotypes, or intermediate markers of like experiences at five-year follow-up (Gooding, Tallent & Matts, schizophrenia, as evidence of increased risk for the disorder 2005). Likewise, a noted feature in the personalities of individuals (Braff, Freedman, Schork & Gottesman, 2007; Cannon & Keller, in the prodromal phases of schizophrenia is social withdrawal; 2006). As suggested by the model, many of these endopheno- recently, Kwapil, Barrantes-Vidal, and Silvia (2007) have found types are genetically influenced, but others result from prenatal that individuals high in the negative dimension of schizotypy, as factors (Geddes, Verdoux, Takei et al. , 1999; McGrath, 1995; measured by the CPPS, are less likely to be involved in intimate Takei, Os & Murray, 1995). relationships than individuals who do not score high on this One endophenotype associated with the schizophrenia dimension. Thus, the CPPS show promise in their abilities to development is premorbid personality dysfunction. Among the identify hypothetically psychosis prone individuals well before measures suggested to assess personality dysfunction indicative theonsetofaclinicallysignificantdisorder. of schizophrenia development are the Chapman Psychosis Proneness Scales (CPPS) and various subscales on the MMPI-2. Evidence for each of these measures as an indicator MMPI indicators of schizophrenia liability of liability to schizophrenia-related disorders is reviewed Among the first efforts to delineate MMPI indicators of schizo- below. phrenia liability were those of Moldin and colleagues (Moldin,

Ó 2009 The Authors. Journal compilation Ó 2009 The Scandinavian Psychological Associations. Published by Blackwell Publishing Ltd., 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA. ISSN 0036-5564. Scand J Psychol 51 (2010) Premorbid indicators of schizophrenia-related psychosis 69

Gottesman, Erlenmeyer-Kimling & Cornblatt, 1990a; Moldin, personality disorders. For example, Solano and De Cha´vez (2000) Rice, Gottesman & Erlenmeyer-Kimling, 1990b) who developed found that 85% of their sample of patients with schizophrenia an index of 13 standard and supplementary MMPI scales. This had premorbid personality disorders. Of these disorders, avoidant index was initially found to be successful at discriminating (32.5%), schizoid (27.5%), paranoid (20%), dependent (20%), behaviorally deviant individuals at high genetic risk to schizo- and schizotypal (12.5%) were the most common. More recently, phrenia from non-deviant individuals also at increased genetic Fogelson, Nuechterlein, and Asarnow (2007) have offered risk for the development of the disorder. further evidence that avoidant personality disorder be considered Several following studies (e.g., Bolinskey, Gottesman, Nichols as a schizophrenia spectrum disorder, by finding that avoidant et al. , 2001; Bolinskey, Gottesman & Nichols, 2003; Carter, personality disorder is an indicator of liability to schizophrenia Parnas, Cannon, Schulsinger & Mednick, 1999) have incorporated even after statistically accounting for paranoid and schizotypal prospective designs to determine MMPI-determined personality personality disorders. Gooding, Tallent, and Matts (2007) have characteristics predictive of future schizophrenia. Bolinskey concurred with that finding. et al. (2001) incorporated a prospective, high-risk paradigm to re-examine the predictive power of the indicators in the Moldin index using SADS-derived (Spitzer & Endicott, 1978) Current study Axis I diagnoses as the basis for criterion group membership. For the present study, hypothetically psychosis prone (HPP) Results suggested that eight MMPI scales ( L, Lie Scale; K, participants were compared to a matched comparison (MC) Defensiveness/Correction Scale; 2780 , a linear combination sample to determine if there are group differences in several of the Depression, Psychasthenia, Schizophrenia, and Social measures associated with psychosis proneness. Specifically, we Introversion scales, respectively (Golden & Meehl, 1979); SOC , hypothesized the following: (a) there would be group differences PSY , PHO , Wiggins’ (1966) Social Maladjustment, Psychoticism, on specific MMPI-2 scores, with the HPP group scoring in the and Phobias Content Scales; Gilberstadt and Gottesman’s 8-6 more deviant direction; (b) there would be higher endorsement scale (Minnesota Veterans Administration Hospital, 1975), and of symptoms of personality disorders within the schizophrenia- SzP , Schizophrenia Proneness (Bolinskey et al. , 2003)) were the related spectrum (i.e., paranoid personality disorder, schizotypal most effective indicators of future onset of schizophrenia-related personality disorder, schizoid personality disorder, avoidant psychosis. Likewise, Carter et al. (1999) found evidence for the personality disorder) among members of HPP group as com- power of five scales in the Moldin index ( F, Infrequency Scale; pared to the MC group; (c) the HPP group would more frequently L, 2780 , Pz , Rosen’s (1962) Paranoid Schizophrenia Scale; endorse history of treatment for mental illness than would the and PHO ) to separate individuals who later developed schizo- MC group; and (d) the HPP group would be less likely than the phrenia from those who developed no psychopathology. More MC group to have ever been involved in an intimate romantic recent evidence of the ability of some of these scales to identify relationship. personality features associated with risk for schizophrenia has been offered by Siira, Wahlberg, Miettunen, La¨ksy, and Tienari (2004). METHODS Each of the previous studies incorporated the original MMPI, rather than the current version of the instrument (MMPI-2; Participants Butcher, Dahlstrom, Graham, Tellegen & Kaemmer, 1989). It is Initial participant pool. Participants were drawn from a sample of 322 possible that the inclusion of newer MMPI-2 scales, such as the (120 males, 202 females) college students between the ages of 18 and Fears ( FRS ) and Bizarre Mentation ( BIZ ) Content Scales, and the 24 years who received course credits for their participation. For inclu- Psychoticism ( PSYC ; Harkness, McNulty & Ben-Porath, 1995) sion in the final sample, participants’ responses had to meet several Personality-Psychopathology 5 scale, might increase predictive validity criteria for the MMPI-2, the CPPS, and the PDQ-IV. Validity power. To date, no prospective high-risk-for-SRP designs have criteria for the CPPS and PDQ-IV were taken from the respective manuals for each instrument and consisted of endorsement of less than three incorporated MMPI-2 assessment in their early stages. items on the CPPS Infrequency scale, less than two items on the Too Good scale of the PDQ-IV, and a score of zero on the Suspect Questionnaire scale of the PDQ-IV; these criteria excluded 31 participants. Use of Personality disturbance MMPI-2 validity criteria for such a study presents somewhat of a Family studies of schizophrenia have indicated a relationship dilemma, as a common problem when examining MMPI-2 profiles is that of separating those profiles that reflect true psychiatric deviance between schizophrenia and personality disorders, such as schizotypal from those that reflect psychometric ‘‘noise.’’ The use of a strict set of personality disorder (Kendler, McGuire, Gruenberg, O’Hare, invalidation or exclusion criteria increases the risk of labeling as invalid Spellman & Walsh, 1993). Certain personality disorders have those profiles which are, in fact, indicative of psychopathology, whereas also been found to be present in the prodromal phase of use of lenient criteria may allow enough noise into the analyses to mask schizophrenia. Indeed, the ‘‘Cluster A’’ disorders (Schizotypal, genuine signals. In an effort to maintain consistency with prior, similar studies (cf. Bolinskey et al. , 2001; Moldin et al. , 1990a), we adopted a Paranoid, and Schizoid) are viewed as being related to schizo- moderate set of exclusion criteria to examine the profile validity of the phrenia. Research, however, has suggested that avoidant personality MMPI-2 profiles in the current study; these criteria consisted of VRIN disorder be included in this group of schizophrenia-related £ 13, TRIN > 5 and < 13, F £ 30, Fb < 20, Fp T score < 120, Cannot

Ó 2009 The Authors. Journal compilation Ó 2009 The Scandinavian Psychological Associations. 70 P. K. Bolinskey and I. I. Gottesman Scand J Psychol 51 (2010)

Table 1. Normative data (means, standard deviations, and reliability ‘‘True’’ or ‘‘False.’’ The current study incorporates the F and Fb validity estimates) for Chapman Psychosis Proneness Scales by gender scales; Scale 6 and Scale 8 from the Clinical scales; a linear combination of Clinical scales 2, 7, 8, and 0 (2780) ; the FRS , BIZ , and CYN Content Males Females scales; PSYC from the PSY-5 scales; SzP (Bolinskey et al. , 2003); PAR , STY , AVD , and SZD from Morey and colleagues’ (Colligan, Morey & WSS Scale M (SD ) a M (SD ) a Offord, 1994; Morey, Waugh & Blashfield, 1985) non-overlapping personality disorder scales for MMPI/MMPI-2; and RC8 (Aberrant PhyAnh 13.71 (6.80) 0.82 9.26 (5.24) 0.78 Experiences ) from the Restructured Clinical scales. These scales were PerAb 6.87 (6.06) 0.89 3.86 (3.49) 0.89 selected because: (a) previous research has suggested them as possible MagId 9.73 (5.83) 0.85 11.43 (3.52) 0.83 markers of psychosis; (b) they are the currently available scale most SocAnh 8.91 (5.12) 0.79 18.49 (8.68) 0.79 similar to an obsolete scale no longer routinely scored as part of an MMPI-2 administration (e.g., the substitution of the BIZ content scale Note : PhyAnh ¼ Revised Physical Anhedonia Scale (Chapman et al. , for the previous PSY content scale and FRS for the previous PHO 1976); PerAb ¼ Perceptual Aberration Scale (Chapman et al. , 1978); content scale); or (c) they are new scales that purport to measure MagId ¼ Magical Ideation Scale (Eckblad & Chapman, 1983); and constructs associated with schizophrenia-related psychosis. All analyses SocAnh ¼ Revised Social Anhedonia Scale (Eckblad et al. , 1982). The incorporated raw scale scores. norms are based upon Caucasian undergraduate students at the University of Wisconsin-Madison and the table provides separate norms PDQ-4. The PDQ-4 (Hyler, 1994) is a 99-item questionnaire that for males and females. Cutoff scores are 1.96 standard deviations above screens for the presence of DSM-IV personality disorders. The the mean. Subjects are considered deviant on a particular measure if questionnaire consists of first-person statements referring to emotions/ their score is equal to or greater than the cutoff score. behaviors that the examinee may have experienced/evidenced consistently over the past several years to which an examinee responds ‘‘True’’ or ‘‘False.’’ The PDQ-4 has been shown to be both reliable and valid (Dubro, Wetzler & Kahn, 1988; Hyler, Skodol, Kellman, Oldham & Say £ 20, and L T score £ 83; 38 additional participants were excluded Rosnick, 1990), although there is evidence (Whyte, Fox & Coxell, 2006) due to these criteria. that respondents may over-report personality disorder symptomology. Given the possibility of over-reporting on the PDQ-4, diagnostic Final sample. The final sample consisted of 51 individuals (10 males, suggestions from the measure were not included in our analyses. 41 females) identified as HPP on the basis of their CPPS scores (see Rather, scores from each PD subscale of the PDQ-4 served as proxies for Table 1) and 51 individuals (10 males, 41 females) in an MC group. the experience of symptoms similar to those an individual with ‡ Criteria for inclusion in the HPP group for males were SocAnh 20, particular personality disorders might experience. Scales included in the ‡ ‡ ‡ PhyAnh 28, MagId 22, or PerAb 19; criteria for females were present study assessed paranoid, schizoid, schizotypal, and avoidant ‡ ‡ ‡ ‡ SocAnh 16, PhyAnh 20, MagId 21, or PerAb 19. It is important symptomology. PDQ-4 data were not available for two members of the to note that inclusion in the HPP group does not necessarily indicate MC group. that the participant is experiencing any psychotic symptoms or will develop actual schizotypy; rather, inclusion simply indicates that they Questionnaire. Participants also completed a questionnaire that asked for have scored beyond the cutoff score on a scale that is associated with demographic information, information regarding personal relationships, psychosis proneness. Age among the males in the HPP group ranged mental health history of the respondent, and mental health history of the ¼ ¼ from 18 through 24 years ( M 19.3, SD 1.83); ethnic group respondent’s family. Variables included in the present study were personal membership consisted of nine Caucasians and one African-American. romantic relationships history and personal mental health history. Among the females in the HPP group age ranged from 18 through ¼ ¼ 25 years ( M 19.0, SD 1.71); ethnic group membership consisted Data collection. All data was gathered in a single assessment session. of 31 Caucasians, 8 African-Americans, 1 Hispanic/Latina, and 1 Completion times ranged from 1.5 hours to 2.75 hours. All participants Asian-American. were allowed to take breaks as necessary, with the caveat that they were In order to control for the possible effect of demographic variables on not to discuss the assessment procedures with their fellow participants. the variables of interest, an MC group was selected whose demographics aligned as closely as possible with the HPP group. Thus, for each HPP participant, an MC participant was matched on (in order) gender, Statistical analyses ethnicity, age, and college major from the remaining participants with valid protocols. When a match was not possible on one of these criteria, MMPI-2 analyses. MANOVA incorporated the 15 MMPI-2 scales as the match was made with the participant closest to the HPP participant the dependent variables and group (HPP vs. MC) as the dependent on that particular criterion. Of the participants in final sample, all were variable. This multivariate test was followed by ANOVA for each matched on gender and ethnicity; 82.3% of participant pairs were also MMPI-A scale; a Bonferroni adjustment of p ¼ 0.0033 was incorporated matched on age (mean difference among non-matched pairs was 1.3 into significance estimations to account for the 15 separate analyses and years), whereas 76.4% of participants were matched on all four criteria effect sizes ( g2) were calculated for each comparison. (gender, ethnicity, age, college major). Age among the males ranged ¼ ¼ from 18 through 23 years ( M 19.4, SD 1.53). Age among the PDQ-4 analyses. Differences on the PDQ-4 were analyzed through ¼ females in the MC group ranged from 18 through 24 years ( M 18.8, MANOVA, incorporating the four personality disorder scales as the ¼ SD 1.40). There were no significant differences in age by gender, dependent variables and group as the independent variable. The multivariate group, or their interaction. test was followed by ANOVA for each PDQ-4 scale, incorporating a Bonferroni adjustment of p ¼ 0.0125.

Instruments Additional analyses. We also examined group differences in history of romantic relationship as well as history of treatment for mental illness. MMPI-2. The MMPI-2 (Butcher et al. , 1989) is a 567-item questionnaire These analyses were carried out using a v2 test of independence. Odds consisting of first-person statements to which an examinee responds ratios and effect sizes (Cramer’s /) were calculated for each comparison.

Ó 2009 The Authors. Journal compilation Ó 2009 The Scandinavian Psychological Associations. Scand J Psychol 51 (2010) Premorbid indicators of schizophrenia-related psychosis 71

Table 2. Means and standard deviations for selected MMPI-2 scale raw reported that they had not, whereas only 6 of 51 MC participants scores with associated F values and effect sizes reported that they had not. This difference in the likelihood to have not been involved in a serious relationship was significant, MMPI-2 Scale HPP ( SD ) MC ( SD ) F g2 v2(1) ¼ 3.980, p ¼ 0.046, Cramer’s / ¼ 0.20. The observed odds F 9.14 (5.67) 6.10 (4.37) 9.18*** 0.08 ratio for lack of significant relationship by group was 2.84 Fb 6.04 (5.11) 3.86 (3.49) 6.31* 0.06 (95% CI ¼ 0.99 to 8.12). Scale 6 12.35 (4.54) 11.43 (3.52) 1.31 0.01 Participants were also asked if they or anyone in their family Scale 8 23.73 (12.32) 18.49 (8.68) 6.15* 0.06 had received treatment for various forms of mental illness 2780 123.80 (25.23) 106.61 (20.58) 14.23*** 0.12 FRS 7.06 (4.08) 5.63 (3.46) 3.65 0.04 (e.g., SRP, depression, mania, AD/HD, etc.). Given the relatively BIZ 5.29 (4.58) 4.76 (3.65) 0.42 0.00 low endorsement rates for the individual questions, data for CYN 15.08 (4.10) 12.63 (4.64) 7.99** 0.07 each of these questions was combined into a single variable of PSYC 7.41 (4.36) 5.71 (3.05) 5.23* 0.05 treatment for any form of mental illness. Of the 51 HPP SzP 11.12 (3.80) 9.49 (2.91) 5.89* 0.06 participants, 8 reported that they had received mental health PAR 5.65 (2.77) 4.65 (2.27) 3.98* 0.04 STY 5.37 (2.86) 3.80 (2.03) 10.19** 0.09 treatment, whereas only 2 of 51 MC participants reported that AVD 7.29 (3.13) 5.55 (2.77) 8.87** 0.08 they had received such treatment. This difference in the SZD 3.73 (2.45) 2.10 (1.81) 14.53*** 0.13 likelihood to have received treatment for mental illness was RC8 4.73 (4.34) 4.00 (3.54) 0.86 0.01 significant, v2(1) ¼ 3.991, p ¼ 0.046, Cramer’s / ¼ 0.20. The ¼ observed odds ratio for treatment by group was 4.56 (95% CI Note : Scores for MMPI-2 scales 7 and 8 are non-K corrected. HPP ¼ hypothetically psychosis prone sample; MC ¼ matched comparison 0.92 to 22.64). Although rates of mental health treatment for sample. 2780 is a linear combination of MMPI-2 scales 2, 7, 8, and 0. family members was not specifically addressed in the current * p < 0.05, ** p < 0.01, *** p < 0.0033. study, it bears noting that no participant endorsed any family N for each group ¼ 51. history of SRP.

Table 3. Means and standard deviations for item endorsement on DISCUSSION selected PDQ-4 scales with associated F values and effect sizes The current study examined whether individuals identified as PDQ-4 Scale HPP ( SD ) MC ( SD ) F g2 being hypothetically psychosis prone on the basis of their CPPS scores also evidenced increased deviancy on other indicators of Paranoid PD 4.00 (1.66) 2.96 (1.67) 9.76** 0.09 schizophrenia-related psychosis and life difficulties. The results Schizoid PD 1.76 (1.72) 1.06 (0.94) 6.38** 0.06 support an affirmative answer. A secondary goal of the Avoidant PD 3.96 (1.90) 2.47 (1.99) 14.72*** 0.13 Schizotypal PD 2.76 (1.97) 2.16 (1.66) 2.72 0.03 current study was to examine the ability of currently available MMPI-2 scales to serve as markers of psychosis proneness. Note : HPP ¼ hypothetically psychosis prone sample ( N ¼ 51); The results for these comparisons are mixed, although not MC ¼ matched comparison sample ( N ¼ 49). entirely unexpected. * p < 0.05, ** p < 0.01, *** p < 0.001. The multivariate test of the selected MMPI-2 scales was significant, which suggests that the linear combination of the selected scales is related to psychosis proneness as assessed RESULTS by the CPPS. With regard to the univariate tests, only scales F, The MANOVA for the selected MMPI-2 scales was significant, 2780 , and SZD met criteria for significance after Bonferroni F(15, 86) ¼ 2.957, p ¼ 0.001. Wilks’ lambda was 0.66, indicating correction ( p < 0.0033). that 34% of the variance in the combination of these MMPI-2 The finding of significant differences by group on scale F is scale scores can be accounted for by group membership. Table 2 consistent with the results of past research (e.g., Carter et al. , displays mean scores by group with associated univariate results 1999; Moldin et al. , 1990b). Although the F scale was initially and effect sizes. created as a measure of validity, it has consistently been demon- PDQ-4 data for two members of the MC group was not strated to be associated with odd experiences and mentations available; thus the MC group for these analyses consisted of 49 (Friedman, Lewak, Nichols & Webb, 2001) at levels that are individuals. The MANOVA for the number of schizophrenia- elevated but below the invalidity threshold. The results of the related personality disorder symptoms endorsed was also current study reinforce the notion, long before any symptoms of significant, F(4, 95) ¼ 5.745, p < 0.001. Wilks’ lambda was psychosis may appear, some individuals are already experiencing 0.80, indicating that 20% of the combined variance in the ways of thinking beyond the ordinary. endorsement of personality disorder-related scale scores can be Differences on 2780 were also found to be significant at the accounted for by group membership. Table 3 displays mean scores most stringent alpha level, a finding that is consistent with by group with associated univariate results and effect sizes. previous studies (Bolinskey et al. , 2001; Carter et al. , 1999; Participants were asked if they had ever been involved in a Moldin et al ., 1990b). This combination of scales was first close romantic relationship. Of the 51 HPP participants, 14 suggested by Golden and Meehl (1979) who attempted to delineate

Ó 2009 The Authors. Journal compilation Ó 2009 The Scandinavian Psychological Associations. 72 P. K. Bolinskey and I. I. Gottesman Scand J Psychol 51 (2010) a group of MMPI items that would discriminate individuals currently manifesting symptoms of psychosis) it might be possessing traits in line with Meehl’s (1962) concept of expected that this group of scales failed to distinguish the schizotypy. Among the behavioral correlates associated with two groups. high scores on 2780 are anhedonia, cognitive slippage, We hypothesized, however, that the individuals identified withdrawal, schizoid traits, avolition, over-sensitivity, flat affect, as HPP would endorse more items from the paranoid, schizoid, emotional instability, overt psychotic symptoms, anxiety, and schizotypal, and avoidant scales of the PDQ-IV than would fearfulness. their comparison participants. The multivariate test was signi- We also found significant differences in scores on Morey and ficant, as were three of the four univariate tests. The significant colleagues’ (Colligan et al. , 1994; Morey et al. , 1985) SZD differences on the paranoid, schizoid, and avoidant scales are in personality disorder scale at the most stringent alpha level. agreement with previous findings (e.g., Fogelson et al. , 2007; Social withdrawal and disinterest were described by Colligan Gooding et al. , 2007). The lack of a significant difference on et al. as being the key personality features associated with high the schizotypal scale is surprising, though it may reflect that scores on this scale. scale’s focus on more ‘‘bizarre’’ symptoms, rather than the With an alpha level of 0.01, scales CYN , STY , and AVD met symptoms of mistrust and withdrawal measured by the other significance criteria. This group of scales assesses constructs scales. such as mild distrust of others’ motives, eccentricity and social Our final two analyses assess behavioral outcomes, rather withdrawal, and social anxiety and low self-esteem, respectively. than ‘‘personality.’’ Our first analysis examined whether HPP Each of these traits has previously been described as a feature individuals had a higher incidence of treatment for mental associated with the prodromal personalities of individuals with illness (regardless of diagnosis) than MC individuals. We schizophrenia. hypothesized that there would be a significant difference as the With alpha levels relaxed even further (i.e., to < 0.05), Fb , odd behaviors and/or social withdrawal of the HPP participants Scale 8 , PSYC , SzP , and PAR would meet criteria for significance. might make them more likely to be referred for treatment. The The findings of small effect sizes ( g2 ¼ 0.06 for each scale) are results supported this hypothesis. Likewise, we hypothesized consistent with previous findings for both scale 8 (Moldin et al. , that HPP participants would be less likely than MC participants 1990b) and SzP (Bolinskey et al. , 2003). The findings for to have ever been involved in a close romantic relationship, Fb , PSYC , and PAR , however, have not previously been reported given that one of the defining features of the prodromal in the literature. Like scale F, scale Fb was initially created as phase of SRP is social withdrawal. This hypothesis, too, was a validity scale; however, Friedman et al. (2001) have noted that supported, and the results are in agreement with Kwapil et al. mild elevations on this scale are suggestive of an ego-syntonic (2007). disturbance, rather than acute distress. Interestingly, Harkness There are a few areas of caution that stand out in the inter- et al. (1995) noted that the PSYC construct was based somewhat pretation of our results. First, our sample was predominantly on the MagId and PerAb scales of the CPPS, so its inclusion in Caucasian and female; this sample is reflective of the population this group of variables is not surprising; that it did not show from which it was drawn, but the lack of diversity within our stronger effect is suggestive that the scale also measures sample may limit generalizability of our results. additional constructs beyond those included in the CPPS. PAR Second, it is possible that we measured a response set was noted by Colligan et al. (1994) to measure interpersonal suggestive of psychosis proneness, rather than an underlying suspiciousness. construct of psychosis proneness. This possibility is unlikely, Note that the only scales that would fail to meet criteria by however, as the HPP participants did not endorse the more the most relaxed standards would be FRS , Scale 6 , BIZ , and extreme symptoms of psychosis (e.g., first-rank symptoms or RC8. FRS was included in the study as a substitute for the overt schizotypal behavior). obsolete MMPI content scale PHO (Wiggins, 1966). Early Third, our reliance on a self-report measure (PDQ-IV) as a examinations (e.g., Bolinskey et al. , 2001; Carter et al. , 1999; proxy for personality disorder-related experiences leads us to Moldin et al. , 1990b) of the MMPIs of individuals who later be less confident in the findings than if we had been able to developed schizophrenia suggested that the PHO scale was incorporate a semi-structured diagnostic interview for personality an effective indicator of schizophrenia liability; more recent disorders. For this reason, we plan to incorporate a semi-structured examinations (e.g., Siira et al. , 2004) have failed to replicate interview in follow-up studies to compensate for possible item these findings. The current result is in line with these more recent over-endorsement on the PDQ. findings. That scales 6, BIZ , and RC8 failed to show significant Fourth, the current study fails to distinguish between the group differences is not necessarily surprising, as these scales positive and negative aspects of schizotypy that are associated tend to measure more active symptomology of schizophrenia- with SRP. Additional data that would help to distinguish between related psychosis, as opposed to characterological dysfunction. these aspects would enhance follow-up studies. Nichols (2006), for example, suggested that RC8 is unique Finally, we do not know if any of our HPP participants will on in its capacity to measure Schneider’s first-rank symptoms actually develop SRP. To ascertain this, a longitudinal study is of schizophrenia. As the current study searched for differences needed. Such a longitudinal study could incorporate each of the among individuals who may be psychosis prone (but not measures from the current study, as well as other endophenotypes

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Ó 2009 The Authors. Journal compilation Ó 2009 The Scandinavian Psychological Associations.