Thought disorder in adolescent-onset schizophrenia

SCHIZOPHRENIA RESEARCH

ELSEVIER

Schizophrenia Research 23 (1997) 147-165

Thought disorder in adolescent-onset schizophrenia’ David Makowski 2,a, Christine Waternauxb,Clara M. Lajonchere’, Robert Dickerd, Neil Smoked,Harold Koplewiczd,DaekeeMine, Nancy R. Mendell”, Deborah L. Levyfv* a Herbert G. Birch Early Childhood Center, Springfield GardensNew York, New York, NY, USA ’ Department of Psychiatry, Columbia College of Physiciansand Surgeons, New York, NY USA ’ Department of Psychology, Washington University, St. Louis, MO, USA d Long Island Jewish Medical Center, New Hyde Park, New York, NY, USA ’ Department of Applied Mathematics and Statistics, SUNY at Stony Brook, Stony Brook, New York, NY, USA f McLean Hospital, 115 Mill Street, Belmont, MA 02178, USA Received 13 May 1996; revision 22 August 1996; accepted 3 September 1996

Abstract

The nature of the thinking disturbances found in adolescent-onset psychotic conditions is not as well-characterized as the thought disorders found in adult psychotic patients. We used the Thought Disorder Index to examine whether schizophrenic patients in whom psychotic symptoms appear in adolescence show the same characteristic features of thought disorder as do adult schizophrenics. Quantitative and qualitative features of thought disorder were assessed in psychiatric inpatients with adolescent-onset schizophrenia, psychotic depression, and nonpsychotic conditions compared with normal control adolescents. Elevated thought disorder occurred in all groups of adolescentshospitalized for an acute episode of psychiatric illness. The magnitude of the elevation and the frequency of occurrence of disordered thinking were greatest in the psychotic adolescents. The qualitative features of the thought disturbances found in the schizophrenic adolescents were distinct from those observed in adolescents with psychotic depression. The thinking of the schizophrenic adolescents resembled that of adult schizophrenics. In both conditions thought disorder is characterized by idiosyncratic word usage, illogical reasoning, perceptual confusion, loss of realistic attunement to the task, and loosely related ideas. Keywords: Thought disorder; Adolescent; Schizophrenia

* Corresponding author: Tel.: + 1617 8552854; Fax: + 1 617 8552778. ‘This work was performed as part of the requirements for the doctoral degree by Dr. Makowski at the Derner Institute of Advanced Psychological Studies, Aldelphi University, Garden City, New York. A portion of this work was presented at the International Congress on Schizophrenia Research, Warm Springs, Virginia, April 4, 1995. ‘Author to whom reprint requests should be addressed: 9 Sauters Lane, Bayport, NY 11705, USA. 0920-9964/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved

PZZSO92@9964(96)00097-7

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1. Introduction

There is general agreement that disordered thinking accompanies adult psychotic conditions (Johnston and Holzman, 1979; Marengo and Harrow, 1985; Andreasen and Grove, 1986; Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987). Although quantity of thought pathology does not distinguish among the functional psychoses, several different methods of assessing thought disorder have substantiated that distinctive features of thought disturbance accompany different psychiatric syndromes (Marengo and Harrow, 1985; Andreasen and Grove, 1986; Harrow and Marengo, 1986; Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987). Little attention has been directed toward characterizing the nature of the thinking disturbances found in adolescent-onset psychotic conditions. Whether schizophrenic patients in whom psychotic symptoms appear at an atypically young age during adolescence show the same characteristic features of thought disorder as do adult schizophrenics, remains an unaddressed empirical question. Earlier age of onset may be associated with greater chronicity and severity of illness (Fish, 1977; Weiner, 1982; Krausz and Muller-Thomsen, 1993; Remschmidt et al., 1994), and possibly with increased genetic loading (Kallman and Roth, 1956), although the evidence for the association between age of onset and severity appears to be equivocal (Asarnow, J.R. et al., 1994). The age of onset for adult schizophrenia begins at about 17 years. The possibility of the illness beginning prior to age 15 was recognized by Kraepelin ( 19 19) and Bleuler (191 l), but both considered such a precocious onset to be rare. Kraepelin estimated that onsets prior to age 10 occurred in 3.5% of cases, and onsets between age lo-15 in 2.7%. Comparably low rates, 0.5-l% before age 10 and 4% before age 15, were reported by Bleuler. Several lines of evidence suggest that there should be similarities between the features of thought disorder shown by both adult and adolescent-onset schizophrenics. First, childhood-onset schizophrenics show many of the same cognitive and electrophysiological deficits observed in adult schizophrenics. These include eye tracking dys-

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function and skin conductance orienting response anomalies (Gordon et al., 1994), event-related potential abnormalities (Strandburg et al., 1994) and limited visual information processing resources (Asarnow, R.F. et al., 1994). Caplan (1994) reported that illogical thinking and looseness, two features of thought disorder commonly observed in adult schizophrenics (Johnston and Holzman, 1979; Holzman et al., 1986; Solovay et al., 1987) characterize the communication deficits of childhood schizophrenic patients. Moreover, comparable clinical symptoms, outcome and treatment response (Spencer and Campbell, 1994; Werry et al., 1994), including therapeutic efficacy of clozapine (Gordon et al., 1994; Remschmidt et al., 1994) are found in both conditions. Second, elevated amounts of disordered thinking have been documented in five published studies of psychiatrically disturbed children and adolescents. Weiner and Exner (1978) examined the prevalence of five categories of disordered thinking (deviant verbalizations, autistic logic, incongruous combinations, fabulized combinations and contaminations) in adolescent patients and non-patients. The adolescent patient samples comprised individuals who had been referred for evaluation of acting out or withdrawn behavior, and they produced significantly more instances of many kinds of thought disorder than did the nonpatient adolescents. Systematic clinical evaluations of these groups were not reported and it is not clear whether their behavioral problems were severe enough to warrant psychiatric hospitalization or which psychiatric syndromes were represented. Arboleda and Holzman (1985) examined quantity of thought disorder in several groups of children and adolescents between the ages of 5 and 16. Their sample included normal controls, individuals whose mothers had a chronic psychotic disorder, and individuals hospitalized for nonpsychotic and psychotic conditions. Individuals hospitalized for a psychotic condition and offspring of psychotic mothers showed similarly elevated amounts of thought disorder, which exceeded those shown by individuals hospitalized for non-psychotic conditions and normal controls. Armstrong et al. (1986) reported that symptom severity in hospitalized

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adolescents was significantly associated with more thought disorder, as assessed by the TDI and Exner’s Schizophrenia Index (Exner, 1985). Tompson et al. (1990) reported that hospitalized children with schizophrenia and schizotypal personality disorder had higher amounts of thought disorder than depressed children. Similarly, Caplan (1994) found illogical thinking and looseness to be equally elevated in children with schizophrenia and schizotypic personality disorder compared with psychiatrically healthy children. Third, the offspring of psychotic parents show elevated amounts of thought disorder even though those children are not clinically ill (Griffith et al., 1980; Parnas et al., 1982; Arboleda and Holzman, 1985). Some of these high-risk children develop schizophrenia-related disorders in adulthood (Parnas et al., 1982), and their prevalence of thought disorder is comparable to that shown by children and adolescents hospitalized for psychotic conditions (Arboleda and Holzman, 1985). These findings in children and adolescents are buttressed by the results of studies of adult relatives of psychiatric patients, who not only show elevated amounts of thought disorder, but also show qualitative features of thought disorder that are similar to those seen in the patients themselves (Johnston and Holzman, 1979; Shenton et al., 1989). The relation between specific psychiatric illnesses and thought disorder was addressed only by Tompson et al. (1990) and Caplan (1994) whose samples of schizophrenics (and schizotypal personality disorder) had a childhood onset. In the other studies mentioned above, the psychiatric patient samples included a heterogeneous group of disorders without reference to specific diagnostic categories. Thus, the quantitative and qualitative features of thought disorder associated with specific adolescent-onset disorders, their specificity and their comparability with adult-onset psychiatric illness could not be addressed. This study addressed the following four hypotheses: (1) patients with adolescent-onset schizophrenia and psychotic depression show elevated amounts of thought disorder compared with adolescents hospitalized for nonpsychotic conditions and psychiatrically healthy adolescents; (2) the thought disorder of adolescent-onset schizophre-

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nits is qualitatively different from that shown by adolescent-onset affective disorders; (3) the components of the disordered thought shown by adolescent-onset schizophrenics are similar to those that characterize adult schizophrenics; (4) developmental immaturity in thinking that is characteristic of adolescence is distinguishable from the thought pathology associated with psychosis.

2. Methods 2.1. Subjects

The total sample comprised 95 adolescents between the ages of 12 and 18 years. Subjects were recruited from a large private medical center in a major metropolitan area. The psychiatric patients were ascertained from consecutive admissions to an inpatient adolescent service and the normal controls were ascertained from consecutive admissions to one of several pediatric and adolescent medicine wards. Each subject and a parent gave written informed consent for participation. Individuals who had a current or past history of drug or alcohol abuse, serious cognitive or intellectual deficits (i.e., a verbal IQ below 70), verified central nervous system disease, or who were not fluent in English, were excluded from participation. Sixty-six of the subjects were hospitalized for a psychiatric illness. The procedures that were used for assigning psychiatric diagnoses are described below. Twenty individuals met DSM-III-R (American Psychiatric Association, 1987) criteria for schizophrenia, 12 for a diagnosis of major depression with psychotic features, and 34 for a nonpsychotic disorder (e.g., major depression without psychotic features, adjustment reaction). The normal control group consisted of 29 adolescents who had been hospitalized for a non-life-threatening medical illness (e.g., minor surgery, asthma, bone fracture) and who had no present or past history of a major psychiatric illness. Five additional normal control subjects were excluded because the parents refused to give consent (n = 3) or because the child’s history indicated serious psychopathology (n = 2). Demographic characteristics of the subject

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groups are presented in Table 1. The groups did not differ with respect to age, which averaged around 15 years in all the groups. The sample of schizophrenics was disproportionately male (80%), as would be expected in young individuals (Iacono and Beiser, 1992), but the ratio of males to females in this group differed significantly only in comparison with the group of nonpsychotic patients, which was predominantly female. Consistent with the young age of the subjects, number of prior hospitalizations averaged about one in all groups. Ethnic composition was evenly split between Caucasians and non-Caucasians (black, oriental, Hispanic, Indian) in all groups except the normal controls, who were primarily Caucasian. 2.1.1. Prior and current psychotropic medication exposure

A majority of the psychiatric patients had had some exposure to psychotropic drugs prior to this hospitalization: 85% of schizophrenics, 58% of psychotic depressives, 38% of nonpsychotics. Antipsychotic medication had been prescribed at some point in the past for 85% of the schizophrenics, 42% of the psychotic depressives, and 6% of the nonpsychotics. Upon admission to the hospital 55% of schizophrenics, 50% of psychotic depres-

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sives and 18% of nonpsychotics were receiving at least one psychotropic medication. By the time thought disorder was assessed, 40% of the schizophrenics, 50% of the psychotic depressives, 74% of the nonpsychotics and all of the normal controls medications. were receiving no psychotropic Among the schizophrenic patients who were medicated at the time of the thought disorder assessment, median time on medication was 5 days for antipsychotics, 16 days for antidepressants, 3 days for lithium, and 5 days for antianxiety agents. For the psychotic depressive and nonpsychotic patients, median time on medication at the time of the thought disorder assessment was 3.5 months and 3 days, respectively, for antipsychotics, 2 months and 1 month, respectively, for antidepressants, and 1 year and 2 days, respectively, for antianxiety agents. 2.1.2. Diagnostic assessment

The diagnoses of the adolescents hospitalized for a psychiatric illness were made by two experienced psychiatrists (RD, NS). These diagnoses were based on: (a) an admission clinical interview about the patient with both the patient and at least one of her/his parents, supplemented by the Kiddie Schedule for Affective Disorders and

Table 1 Demographic and clinical characteristics of the sample

N

Age” Sexb (M/F) Ethnicity (% Caucasian) Number of hospitalizations” Duration of current hospitalization (day~)~ TDI administered (days) Estimated verbal IQf

Schizophrenics

Psychotic depressives

Nonpsychotics

Normal controls

20 15.5+ 1.96 [16] 12-18 16/4 (80%) 50% l.lkO.3 50.1 f 36.3 [45]

12 14.8 + 1.5 [ 14.5112-17 616 (50%) 50% 1.3 +0.65 40.5+ 18.8 [45]

34 14.7k1.9 [15]12-18 13/21 (38%) 56% 1.03kO.2 33.25 17 [29.5]

29 14.9k1.52 [15]12-18 16/13 (55%) 76% l.lkO.3 4.1k3.3 [3]

5.Ok4.6 [3] 89.9+ 14.1 [90]

4.25* 3.96 [2.5] 98.6+ 18.6 [94]

4.53 k4.4 [3.5] 99.8 & 12.9 [ 1001

1.5k1.8 [l] 106.2&15.1 [loo]

Mean + standard deviation [median]; all F-values are based on ANOVA aFwn, = 0.83, p=O.48. bSchizophrenics vs nonpsychotics, Yates corrected xzo, = 7.2, p < 0.007. cFC3,88j =2.39, p=O.O7. dF (,,,,,=22.73, p =O.OOOl.

Schizophrenics vs normal controls, t,47j=- 7 64, p=O.OOOl; psychotic depressives vs normal controls, t 09j= -2.49, p=O.O15; nonpsychotics vs normal controls, ttel)= -5.12, p=O.OOOl. Schizophrenics vs normal controls, tcd7) = -3.27, p=O.O015. =F@,91)=4.89, p=O.O034. ‘N= 11 schizophrenics, 9 psychotic depressives, 15 nonpsychotics, 29 normal controls. Normal controls vs schizophrenics, tt38J = 3.07, p=O.O032; nonpsychotics vs normal controls, ttel)= -2.18, p=O.O32.

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Schizophrenia-Epidemiological Version (Kiddie SADS-E) (Puig-Antich and Chambers, 1978) interview; (b) behavioral data (nurse’s notes, mental status exams, progress notes) obtained during the current hospitalization; and (c) a review of all available medical records pertaining to previous inpatient and outpatient psychiatric treatment. The final ‘best estimate’ DSM-III-R diagnosis was made upon discharge by one of these two psychiatrists without knowledge of the results of the thought disorder assessment. Each normal control subject and one of his/her parents were interviewed by one of us (DM) using the Kiddie SADS-E, in order to ascertain that the child had never suffered from an Axis I disorder. 2.2. Procedures 2.2.1. Intellectualfunctioning

The Vocabulary subtest of either the WAIS-R or WISC-R ( Wechsler, 1974, 198 1) depending on the subject’s age, was administered to verify a verbal IQ (VIQ) of at least 70. Scores on the vocabulary subtest of the Wechsler Adult Intelligence Scale (WAIS-R) correlate 0.86 with VIQ and are considered to be a valid screening measure for cognitive or intellectual deficits (Matarazzo, 1972). For logistical reasons only a subgroup of the sample (11 schizophrenics, nine psychotic depressives, 15 nonpsychotics, 29 normal controls) could be tested, but all subjects were considered to be of at least normal intelligence based on clinical examination. Estimated VIQ of the subjects tested in each group are presented in Table 1. 2.2.2. Thought disorder assessment

Thought disorder was assessed using the Thought Disorder Index (TDI) (Johnston and Holzman, 1979; Solovay et al., 1986). The TDI can be used to quantify the amount and severity of disordered thinking, and to identify qualitative features of thought disorder. The TDI includes 23 categories of thought slippage at four levels of severity. Examples of mild thought slippage include peculiar verbalizations and mild combinatory thinking. Moderately disordered thinking includes phenomena such as looseness, idiosyn-

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cratic symbolism, and queer use of language. At the more severe end of the spectrum one finds autistic logic, more serious forms of combinatory thinking (e.g., confabulation, contamination), neologisms, and incoherence. The TDI has been shown to be a reliable and valid metric for assessing thought disorder in adults (Johnston and Holzman, 1979; Shenton et al., 1987; Solovay et al., 1987; Coleman et al., 1993) and in children and adolescents (Arboleda and Holzman, 1985), regardless of social class, ethnicity (Haimo and Holzman, 1979) or intelligence level (Johnston and Holzman, 1979). Table 2 gives examples of scorable responses in selected TDI categories. The administration of the Rorschach and the scoring of thought disorder followed the procedures described in Solovay et al. (1986). Briefly, the patient’s responses to ten cards of the Rorschach were audio-recorded for verbatim transcription. All identifying information was removed from the typed transcript, except for a four-digit random number. Both the administration and scoring of the responses were conducted by investigators who were blind to diagnosis. All Rorschach protocols were scored by at least two investigators (DM and DL) with extensive experience in administering and scoring the TDI. TDI scoring reliability for these investigators is excellent (Coleman et al., 1993). Each investigator scored the protocols independently, after which consensus scores were assigned. The thought disorder assessment was carried out as close to admission as possible to minimize the dampening effect of psychotropic drug treatment on thought disorder. TDI data were obtained in the normal control subjects within a significantly shorter time after admission (1.5 days on average) than in the psychiatric subjects, who did not differ from each other (4-5 days on average) (see Table 1). The duration of the current hospitalization was also significantly shorter in the controls than in each of the psychiatric patient groups, which did not differ from each other. These group differences reflect the comparatively less severe nature of the medical problems for which the normal controls were hospitalized. The Total TDI score was computed by using

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Table 2 Examples

of selected

thought

disorder

index

et al. j Schizophrenia

categories

by severity

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level

0.25 Level Peculiar

word

usage

Inappropriate Flippancy

distance

Incongruous

combination

“rectangularly speaking” “skin approximations of front an’ hind feet” “some kind of botanical construction” “cranial skull” “I get too upset when I look at this card.” “I. Magnin’s window, Well, it’s got be a very fur in 1993!” A. Arbitrary forrncolor: “pink cauliflower” “green handlebar moustache” BInappropriate activity: “elephants scaling a wall” C. Composite response: “some type of phallic figure with wings” “a man with a bird’s head”

0.50 Level Queer verbalization

Looseness Idiosyncratic

symbolism

Fabulized Playful

(color)

combination confabulation

0.75 Level Absurd

Autistic

store

that does not care about

comedian

also. Las Vegas

the origin

of man is in Africa

knee” each

other,

cabbage

working

heads,

Confabulation 1.00 Level Incoherent

“medical and scientific also . . very . disastrous there’s evil mutation about “levatory steps” “megatoid” “a butterfly of blood” “a bow tie table”

Neologism Contamination

mutation, but and evil mutation. mind enslavement”

formula:

Total TDI score

=[0.25(A)+0.50(B)+0.75(C)+l.OO(D)]/R

x 100

where A =number of responses scored at the 0.25 severity level; B=number of responses scored at

that’s so there’s

and that’s

they’re

healthy . mutation, good mutation about

selling

on additional why it looks

just

“a bat that’s part man and part fish” “wolves are synomymous with bears” “modem art junk interpretation of a prehistoric fish” falling from above rather “red things falling from outer space , because they’re below. if they were on the bottom of the picture they’d be more like burial figures” “a woman with her hair on fire and evil spirits trying to condemn her soul”

logic

the following

“facial frontage” “a foxed comic dog” “the echo of a picture” “an antiquitous resemblance of pagan worship” “Big Foot, that’s hilarious. I’m an international acts for Las Vegas” “And Africa being red symbolizes that maybe red” “Two fetal bears on a coral reef” “Two bears dancing with a butterfly on their “dueling legumes. evil potatoes spitting at wrestling”

expensive

kind

than

of

from

an’ there’s telepathy. an’

the 0.50 severity level; C=number of responses scored at the 0.75 severity level; D=number of responses scored at the 1.00 severity level; R= total number of Rorschach responses. Individual differences in verbal productivity were controlled by dividing the Total TDI score by the total number of Rorschach responses.

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2.3. Statistical analyses

For the statistical analyses raw Total TDI scores were log transformed in order to better approximate a normal distribution with equal variance within groups. Raw Total TDI scores are reported in the descriptive material in the tables and the text. The Scheffe test was used where appropriate to adjust for multiple comparisons in the parametric statistical analyses. The Bonferroni correction was used where appropriate to adjust for multiple comparisons in the nonparametric statistical analyses. One-sided tests were done whenever greater abnormality was hypothesized in one or more of the patient groups. 2.3.1. Amount of thought disorder

Group differences in total amount of thought disorder were examined using general linear model analysis of variance (ANOVA) and planned comparisons.

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thought disorder, each of which had an eigenvalue greater than 1.0 and accounted for at least 5% of the variance. Factor scores, using unit weighting, were generated for each subject based on the number of instances of thought disordered responses associated with that factor. Second, we identified a group of ‘post hoc’ factors by combining those empiric factors (and the individual TDI categories they reflected) that best differentiated among groups and that seemed to reflect conceptually parsimonious clusters. Group differences in the use of the empiric and post hoc factors were assessed using a general linear model ANOVA and planned comparisons. Third, a discriminant function analysis was used to assess how well the empiric and post hoc factor scores classified patients as schizophrenic or nonschizophrenic. Similar methods of data analysis have been used in studies of adults (Johnston and Holzman, 1979; Shenton et al., 1987, 1989; Solovay et al., 1987). 2.3.4. Effects of potential covariates

2.3.2. Severity of thought disorder

The number of instances of thought disorder at each of the four severity levels (0.25, 0.50, 0.75, 1.0) was calculated for each subject. Group comparisons at the 0.25 and 0.50 severity levels were assessed using general linear model ANOVA and planned comparisons. Because of the relative paucity of thought disordered responses at the 0.75 severity level, the Mann-Whitney test was used to compare groups. Responses at the 1.00 severity level were too rare to warrant statistical analysis. The same procedures were used to compare the groups on the proportion of all thought disordered responses at the four severity levels. 2.3.3. Thought disorder profiles

Qualitative differences in thought disorder associated with diagnosis were assessed in three ways. First, a group of ‘empiric’ factors was derived from a principal components analysis, followed by a variance maximization (VARIMAX) rotation. Twenty-two TDI categories were included in the principal components analysis. Fragmentation was excluded, because no subject gave a response warranting use of this TDI category. Seven factors reflected conceptually parsimonious dimensions of

Arboleda and Holzman (1985) found that even psychiatrically healthy adolescents show levels of thought disorder that are somewhat elevated compared with psychiatrically healthy adults. In their sample of normal control children, younger age was modestly (r = -0.26) associated with a higher Total TDI score, possibly reflecting developmental features of cognitive maturation. Caplan (1994) also reported an association between younger age and amount of thought disorder in both schizophrenic and normal children. In this sample of normal control adolescents, however, age was not significantly correlated with Total TDI score (Spearman correlation = 0.12, p = 0.54). An analysis of covariance (ANCOVA) was carried out to assess the effects of age on Total TDI scores and to determine whether age effects differed among the groups. Older subjects tended to have higher TDI scores (Fc6,19)= 1.98, p = 0.08). The interaction of age and diagnosis was not statistically significant (Fc6,i9)= 1.46, p = 0.1 ), indicating that the effects of age on thought disorder were uniform among the four groups. Diagnosis, however, was significantly related to Total TDI score (Fmsa, = 4.84, p=O.O003), as would be expected. Because developmental differences in cognitive

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maturation were not a confounding variable in the Total TDI score, no adjustment for age was made in the statistical analyses. Scores on the Vocabulary subtest of the WAIS-R or WISC-R, which allow a reliable estimate of Verbal IQ (VIQ), were significantly higher in normal controls than in schizophrenics (see Table 1). Vocabulary subtest scores were not significantly associated with Total TDI score, however (Spearman correlation = -0.215, p = 0.09,n = 64), and therefore they were not covaried in the statistical analyses. These findings are consistent with the TDI results reported by Johnston and Holzman (1979) in adult populations and by Arboleda and Holzman (1985) in children and adolescents as well as the relation between full scale IQ and thought disorder in normal control and schizophrenic children described by Caplan et al. (1992).

3. Results 3.1. Amount of thought disorder

Table 3 presents summary information on Total TDI scores. The subject groups differed significantly in Total TDI score. The mean Total TDI scores ranged from a low of 3.98 in the normal controls to a high of 20.81 in the schizophrenic patients. Planned comparisons revealed that the mean Total TDI score of each of the psychiatric patient groups was significantly higher than the

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mean score of the normal controls, but none of the patient groups differed from each other. Average number of thought disordered responses, however, did distinguish among the groups. Both the schizophrenics and the psychotic depressives had significantly more thought disordered responses than either the nonpsychotic patients or the normal control subjects. Neither the higher mean Total TDI scores of the patients nor the higher average number of thought disordered responses of the psychotic patients were a function of greater verbal productivity. Verbal productivity was estimated from the total number of Rorschach responses (Johnston and Holztnan, 1979) and the groups did not differ significantly on this variable. These results indicate that elevated thought disorder is a nonspecific symptom in adolescents hospitalized for an acute episode of psychiatric illness. Both the magnitude of the elevation and the frequency of occurrence of disordered thinking are greatest in the psychotic disorders. Elevated thought disorder relative to normal controls is also seen in nonpsychotic conditions. The highest Total TDI score among the normal control subjects was 11.5. Total TDI scores exceeding this value were observed in 55% of the schizophrenic, 50% of the psychotic depressives, and 23.5% of the nonpsychotic patients. Thus, all three indices, prevalence of Total TDI scores greater than 11.5, average Total TDI score and number of thought disordered responses, increase as one moves from the nonpsychotic conditions to the psychotic syndromes.

Table 3 Total thought disorder index scores, number of thought disordered responses and number of Rorschach responses by diagnostic group Group

N

Total TDI score*

No. of thought disordered responsesb

No. of Rorschach responses”

Schizophrenics Psychotic depressives Nonpsychotics Normal controls

20 12 34 29

20.81 k26.2 [14] O-120 14.13 k 12.63 [ 10.51 O-46 6.94k6.07 [5.7] O-26 3.9853.29 [3] O-11.5

10.7 k8.8 10.8k8.7 4.9f4.4 3.Ok2.3

22.4 & 13.0 [20] 5-60 27.6+ 12.9 [23.5] 15-63 22.2k7.2 [21.5] 13-40 22.3 k4.8 [22] 14-31

[ 10.51 O-41 [7.5] O-25 [4] o-15 [2] O-10

Mean &standard deviation [median]; F-values are based on ANOVA. ‘Schizophrenics vs normal controls, FC3,s1)= - 4.67, p c 0.0025 (one-sided); psychotic depressives vs normal controls, Fo,al) = - 3.15, ~~0.0125 (one-sided); nonpsychotics vs normal controls, Fo9r, = -3.11, p ~0.025 (one-sided). bSchizophrenics vs normal controls, Fogi)= - 4.58, p
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one subject, a psychotic depressive, produced one response at the 1.0 level. Almost every subject produced at least one instance of the kind of very mild thought slippage that receives a score at the 0.25 level: 19/20 schizophrenics, 1 l/12 psychotic depressives, 30/34 nonpsychotic patients, and 25/29 controls. As severity level increased, however, proportionately fewer subjects in each group produced at least one storable response. As Table 4 also shows, the decline in use of progressively more severe TDI categories was particularly obvious in the nonpsychotics and normal controls compared with the schizophrenics and psychotic depressives. Nearly half of the schizophrenics (45%) and more than half of the psychotic depressives (58%) produced at least one response at the 0.75 severity level, in contrast to about one-quarter of the nonpsychotics and only 7% of the normal controls. Most of the thought disorder that occurred in all groups was relatively mild. It was the increased frequency of mild thought disorder and its co-occurrence with more severe kinds of thought disorder that distinguished psychiatrically ill, especially psychotic, adolescents from psychiatrically healthy adolescents. The proportion of thought disorder that was accounted for by responses at each severity level reflects this pattern of findings. Responses at the 0.25 severity level accounted for 73, 69, 75, and 85% of the thought disorder in schizophrenics, psychotic depressives, nonpsychotics, and normal controls, respectively. Responses at the 0.50 level accounted for 18% of the thought disorder in schizophrenics, 17% of the thought disorder in psychotic depressives and non-

3.2. Severity of thought disorder

The psychotic adolescents showed more thought disorder at all levels of severity than did the nonpsychotic patients and normal controls. Table 4 shows the frequency with which thought disordered responses at each of the four severity levels occurred in the subject groups. Thought disordered responses at the 0.25 severity level occurred significantly more often among both the schizophrenic and psychotic depressive patients, who averaged 7-8 such responses, than among nonpsychotic patients and normal control subjects, who averaged 2-3 (schizophrenics vs normal controls, FC3,91)= - 4.01, p < 0.0025; psychotic depressives vs normal controls, FC:(3,91) = - 3.8 1, p < 0.0025; schizophrenics vs nonpsychotics, F C3,91) = 3.23, p < 0.0125; psychotic depressives vs nonpsychotics, FC3,91)= 3.13, ~~0.025). Responses at the 0.50 severity level distinguished schizophrenic patients, who averaged 2.5 such instances of thought disorder, from normal controls (Fp,wj = - 3.11, p < 0.025), in whom the frequency of these responses averaged 0.5-1.0. Psychotic depressive patients gave an average of 1.4 such responses. Both schizophrenic and psychotic depressive patients had significantly more responses at the 0.75 severity level, averaging 1.2 and 1.7, respectively, than did normal controls (schizophrenics vs normal controls, MannWhitney Z= - 3.30, p =0.003; psychotic depressives vs normal controls, Mann-Whitney Z= - 3.74, p =0.0007), who averaged 0.07 such responses. Only two normal controls gave one response each at this moderately severe level. Only Table 4 Proportion

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of subjects who gave responses at each severity level and mean number of responses at each of four severity levels

Group

% of subjects using at least one 0.25 level response

Mean no. of 0.25 responses

% of subjects using at least one 0.50 level response

Mean no. of 0.50 responses

% of subjects using at least one 0.75 level response

Mean no. of 0.75 responses

% of subjects using at least one 1.0 level response

Mean no. of 1.0 responses

Schizophrenics Psychotic depressives Nonpsychotics Normal controls

95 92

7.1 7.7

75 67

2.45 1.4

45 58

1.2 1.7

0 8

0 0.8

85 86

3.4 2.4

44 31

1.0 0.48

26.5 7

0.53 0.07

0 0

0 0

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psychotics, and 13% of the thought disorder in the normal controls. For the 0.75 level, the corresponding figures are 9, 13.5, 8, and 2%. Only one psychotic depressive had a response at the 1.O level and it accounted for 0.4% of the thought disorder in this group. Responses at the 0.75 severity level accounted for a significantly higher proportion of thought disordered responses in schizophrenics (Mann-Whitney Z=2.91,p=O.O11) and psychotic depressives (Mann-Whitney Z = - 3.50, p = 0.0014) than in normal controls. 3.3. Thought disorder profiles 3.3.1. Empiric factors

We generated a set of empiric factors that utilized the data from the subjects in this study. Seven interpretable factors emerged from a principal components factor analysis with a varimax rotation: Psychotic Reasoning, Psychotic Disorganization, Loss of Set, Associative Looseness, Psychotic Looseness, Confusion, and Playful Looseness. Table 5 presents the resulting factors after rotation, their composition, their eigenvalues, and the proportion of variance accounted for by the factors. Factor scores using unit weightings were computed for each subject by summing the total number of thought disordered Table 5 Principal Empiric

components factor

Psychotic

Reasoning

Psychotic

Disorganization

Loss

of Set

Associative Psychotic

Looseness Looseness

Confusion Playful

Looseness

analysis

of TDI

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responses in the categories that loaded on a particular factor. The schizophrenic group showed elevations on all seven of the empiric factors. The Psychotic Reasoning, Loss of Set and Confusion factors seemed to be ‘schizophrenia’ factors. Schizophrenic adolescents had significantly higher scores on the Psychotic Reasoning and Confusion factors than normal control adolescents and showed a trend toward statistically significant elevations on these factors relative to the nonpsychotic psychiatric patients (see Fig. 1). The TDI categories that load on the Psychotic Reasoning and Confusion factors reflect deviant use of language that is more severe than peculiar word usage, fallacious reasoning, loosely related conceptual formulations, and confusion about what is being perceived. Loss of Set distinguished schizophrenics from both the nonpsychotic patients and the normal controls. Although the Loss of Set factor includes only TDI categories at the mildest severity level, it was primarily the schizophrenic adolescents for whom the task became so real that percepts were inappropriately charged with affect or interpreted concretely. None of the normal controls produced a response that used a TDI category associated with any of these factors.

categories Categories

loading

Queer verbalization Looseness Autistic logic Clang Incoherent Neologism Peculiar verbalization Inappropriate distance Flippancy Idiosyncratic symbolism Confabulation Incongruous combination Contamination Confusion Autistic logic Relationship verbalization Playful confabulation

Eigenvalue

% of variance

3.51

16.7

2.38

11.3

1.97

9.4

1.57

1.5

1.52

1.2

1.34

6.4

1.1

5.4

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157

EMPIRIC FACTORS Diagnostic Groups ISchizophrenics

PsychoticDepressivesmNonpsychotics UNorrnal Controls

/ i

0.8 0.6 w .-z 3 gj

0.2

k

0

0.4

-0.2

Fig. 1. ANOVA results on empiric factors (adjusted for multiple comparisons based on the Scheffe test; one-sided). Psychotic reasoning: schizophrenics vs normal controls, FogI) = - 2.52, p ~0.05; schizophrenics vs nonpsychotics, F,,,,,, =2.44, p ~0.125. Loss of set: schizophrenics vs normal controls, F,,,,,,= - 3.64, pi 0.005; schizophrenics vs nonpsychotics, FogI) = 2.83, pi 0.025. Confusion: schizophrenics vs normal controls, Fc3,91r= - 2.65, ~~0.05; schizophrenics vs nonpsychotics, Fo,,,, =2.44, p
The Psychotic Disorganization factor seems to be a general psychosis factor. Both schizophrenics and psychotic depressives scored significantly higher on this factor than did normal controls. Psychotic depressive patients also had a significantly higher score on this factor than did nonpsychotic patients. One normal control and six nonpsychotic patients produced more than three responses in a TDI category that loaded on this factor which, in all instances, involved mildly stilted use of language. Incoherent responses and

neologisms, the other TDI categories that loaded on this factor, reflect severe thought disorganization and never occurred in a normal control subject or in a nonpsychotic patient. The Associative Looseness and Psychotic Looseness factors seem to define an ‘affective psychosis’ factor. The Associative Looseness factor distinguished psychotic depressives from normal controls. Only one normal subject produced a response using a TDI category that loaded on this factor. Associative Looseness, which comprises the

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TDI categories, Idiosyncratic Symbolism and Confabulation, denotes a thought process in which percepts are arbitrarily embellished by personal meanings to an extent that reality attunement to the task is compromised. Psychotic Looseness, which comprises Incongruous Combinations and Contaminations, distinguished psychotic depression patients from normal controls, and bordered on statistical significance in distinguishing psychotic depressives from nonpsychotic patients as well. Only one normal control showed more than three Incongruous Combination responses. There was no main effect of group on the Playful Looseness factor and none of the planned comparisons was statistically significant. Fig. 1 shows the frequency with which the subject groups showed thought disordered responses in each of the six empiric categories that distinguished between the subject groups. The discriminant function correctly classified 80% of the subjects (x$,=15.92, p=O.OOl). The proportion of nonschizophrenics that was correctly classified by the discriminant function, or specificity (87%), was substantially better than sensitivity (55%), the proportion of schizophrenics that was correctly classified by the discriminant function. The empiric factors that contributed to distinguishing between schizophrenics and nonschizophrenics were Psychotic Reasoning (p = 0.02), Psychotic Disorganization (p=O.O9) and Loss of Set (p= 0.03). The effect size (within group standard deviation= 1) of the discriminant function in distinguishing between schizophrenics (mean discriminant score of 1.0) and nonschizophrenics (mean discriminant score of -0.3) was large (1.3). The relatively low sensitivity of the discriminant function reflects the fact that some schizophrenic adolescents, like adult patients, have either no thought disorder or minimal thought disorder. When only schizophrenic patients with thought disorder were considered, the effect size increased, as would be expected, to 1.9. Schizophrenics had a mean discriminant score of 1.6 and nonschizophrenics had a mean discriminant score of -0.32. Classification accuracy increased to 86% in distinguishing schizophrenic from nonschizophrenic adolescents (&, = 24.5, p = 0.004), sensitivity increased to 67%, specificity increased to 89%. The

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empiric factors that contributed to distinguishing between schizophrenics and nonschizophrenics were Psychotic Reasoning (p =0.0006), Loss of Set (p=O.O041), and Psychotic Looseness (p= 0.04). 3.3.2. Post hoc factors

Following the procedures employed in studies of adult psychotic patients (Shenton et al., 1987; Solovay et al., 1987) we combined those empiric factors that best differentiated the groups and that seemed to reflect conceptually meaningful groupings of thought disorder categories. In this way, we identified three post hoc factors (see Table 6). As with the empiric factors, the schizophrenic group showed elevations on all of the post hoc factors. The first post hoc factor, which we named Illogical Reasoning and Loss of Set, included all of the TDI categories in the Psychotic Reasoning, Loss of Set and Confusion empiric factors except for clangs and flippancy. The second post hoc factor was named General Psychotic Thought Disorganization and was identical to the Psychotic Disorganization empiric factor. The third factor, Ideational Fusing, included the TDT categories in the Associative Looseness and Psychotic Looseness empiric factors. Schizophrenics scored significantly higher than normal controls and nonpsychotic patients on the Illogical Reasoning/Loss of Set factor, and showed a trend toward statistically significant elevations relative to psychotically depressed patients. On the Table 6 Post hoc factors for TDI categories Factor

Categories

Illogical Reasoning and Loss of Set

Inappropriate distance Queer verbalization Looseness Confusion Autistic logic Peculiar verbalization Incoherent Neologism Incongruous combination Idiosyncratic symbolism Confabulation Contamination

General Psychotic Thought Disorganization Ideational Fusing

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Ideational Fusing factor, psychotic depressives had significantly higher scores than nonpsychotics and normal controls, and schizophrenics showed a trend toward being significantly higher than normal controls, suggesting that both Ideational Fusing and General Psychotic Disorganization were non-specific psychotic state factors. Fig. 2 shows the frequency with which the subject groups showed thought disordered responses in each of the three post hoc factors. The discriminant function correctly classified 73.7% of the subjects (xtr,=8.8, p=O.O03). Specificity was 78.7% and sensitivity was 55%. Only the Illogical Reasoning/Loss of Set post hoc

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159

factor contributed significantly (p = 0.00004) to distinguishing between schizophrenics and nonschizophrenics. Thus, the discriminant score can be simply the Illogical Reasoning/Loss of Set factor score or any linear transformation of this score. 3.4. Medication efects

In order to assess the effects of psychotropic medication on thought disorder, we compared the Total TDI scores of the 27 patients receiving psychotropic medication of any kind with those of the 39 unmedicated patients. Although within each

POSTHOCFACTORS Diagnostic Groups

0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 I

Fig. 2. ANOVA results on post hoc factors (adjusted for multiple comparisons based on the Scheffe test; one-sided). Illogical reasoning and loss of set: schizophrenics vs normal controls, FogI) = - 3.8O,p
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diagnostic group medicated patients had less thought disorder than unmedicated patients, neither medication condition nor the interaction of medication condition by diagnostic group was statistically significant. Table 7 presents the Total TDI scores of these groups. Similar findings were obtained when only the effect of antipsychotic medications was considered. Schizophrenic adolescents who were receiving antipsychotic drugs had lower Total TDI scores (n = 12; mean, 18.44; SD, 13.43) than schizophrenics who were not receiving antipsychotic medication (n=S; mean, 24.4; SD, 39.44) (ql*) = 0.27, ~~0.8). An identical pattern of results was obtained when the effect of antipsychotic medication was considered in psychotic depressive and schizophrenic patients jointly.

4. Discussion We are now in a position to evaluate the four hypotheses posed in this study. (1) Our data show that all adolescents hospitalized for a psychiatric illness had elevated levels of thought disorder when compared with the normal control group. The magnitude of the increase in thought disorder was greatest in the schizophrenic and psychotic depressive adolescents, who also had more thought disordered responses than did the nonpsychotic patients and the normal controls. (2) The thought disorder of adolescent-onset schizophrenics was qualitatively different from that shown by adolescentonset affective disorders. (3) The components of the disordered thought shown by adolescentonset schizophrenics were very similar to those

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that characterize adult schizophrenics. (4) Developmental immaturity in thinking that is characteristic of adolescence can be distinguished from the thought pathology associated with psychosis. 4.1. Quantity of thought disorder

Increased quantity of thought disorder distinguished all three groups of adolescent psychiatric patients from normal controls. This increase was evident in the mean Total TDI score, the range of Total TDI scores, the mean number of thought disordered responses, and the prevalence of thought disordered responses exceeding the upper limit of the range found in normal control adolescents. The magnitude of the increase in these quantitative indices of thought disorder was greatest in the adolescent-onset schizophrenics and lowest in the nonpsychotic patients. 4.2. Comparison of adolescent and ad&psychiatric patients

These results demonstrate that patients with adolescent-onset psychotic conditions show elevated amounts of thought disorder, and that the characteristics of the thought disturbances found in schizophrenic adolescents are qualitatively distinct from those observed in adolescents with psychotic depression. The thinking of the schizophrenic adolescents was characterized by idiosyncratic word usage, illogical reasoning, perceptual confusion, loss of realistic attunement to the task, and loosely related ideas. Deviant verbalizations occurred at all levels of severity, ranging from

Table 7 Effects of psychotropic medication on total TDI score by diagnostic group Group

Schizophrenics Psychotic depressives Nonpsychotics All patients

Umnedicated patients

Medicated patients

N

Total TDI score

N

Total TDI score

8 6 25 39

24.4k39.4 [10.4] 15.9k7.4 [17.2] 1.5k6.6 [6.2] 12.3 f 19.2 [9.6]

12 6 9 27

18.4k13.4 [16.8] 12.4* 17.0 [7.3] 5.4 k4.2 [4X] 12.7+ 13.1 [9.4]

Mean k standard deviation [median]. F ,5,60j=2.05, p=O.O84. Group: Fo60j= 4 68, p=O.O13. Medication condition: = 0.90. Group x medication condition: Fo60j = 0.44, p = 0.65.

p

Fo,,,,=O.O1,

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frequent occurrences of peculiar word usage to the more severely stilted expressions associated with queer responses, and even included an occasional tendency to produce neologisms. Both the elevated amount of thought disorder and the qualitative distinctiveness of the thought disorder shown by schizophrenic adolescents are remarkably similar to results using the TDI in adult schizophrenics (Johnston and Holzman, 1979; Holzman et al., 1986; Solovay et al., 1987) and to findings in childhood schizophrenics in which the TDI was not used (Tompson et al., 1990; Caplan, 1994). The thinking disorders of the schizophrenics also included features of combinatory activity that covered the spectrum of severity, from the mild incongruities that occurred in all the groups, to the idiosyncratic interpretations, personalized elaborations and merging of unrelated percepts that reflect delusional ideas. Unstable control over associative and conceptual processes was particularly prominent in the psychotic depressives. Both groups of psychotic patients shared a predilection to give high rates of peculiar use of language and were the only subjects in this study to produce responses with incoherent or neologistic features, reflecting generalized psychotic disorganization. In these respects as well, the thinking of psychotic adolescents resembles that of schizophrenic and bipolar adults, in whom combinatory thinking is prominent. None of the adolescents, however, displayed the playfulness and extravagance shown by adult manic patients. The nonspecificity of elevated quantity of thought disorder in patients with adolescent-onset psychotic conditions parallels the pattern of findings reported in adult patients who have been assessed using the TDI. First, among adult psychiatric patients, as is true of the adolescents, schizophrenics show the largest quantity of thought disorder (Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987). Second, quantity of thought disorder did not distinguish between adolescent-onset psychotic conditions, although it did distinguish both groups from psychiatrically healthy adolescents. Similarly, Shenton et al. (1987) and Solovay et al. (1987) found high amounts of thought disorder in adult patients with schizophrenia, schizo-affective illness (both manic and

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depressed), and mania compared with normal controls. Further, the amount of thought disorder shown by these adolescent-onset schizophrenics is quite similar to the values reported by investigators who studied adult patients using the same instrument in the same manner. The mean Total TDI score of adult schizophrenics has ranged between 16.8 and 34.6 (Johnston and Holzman, 1979; Hurt et al., 1983; Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987; Levy et al., 1993) and our adolescent schizophrenic patients had a mean of 20.8. Neither Johnston and Holzman (1979) nor Solovay et al. (1987) studied adults with psychotic depressive disorders. The range of Total TDI scores in both groups of psychotic adolescents, which reached severely elevated levels, indicates that states of florid thought disorganization accompany these acute episodes, as is also found in psychotic adults. The mean Total TDI score of the adolescents with nonpsychotic conditions, 6.94, is comparable with that of nonpsychotic adults, 9.73, although the amount of thought disorder in adult nonpsychotics has not been found to differ significantly from that of normal controls (Johnston and Holzman, 1979) as was the case in our sample, in which the nonpsychotic adolescents showed significantly more thought disorder than did the normal controls. 4.3. Comparison with other studies of adolescent patients

Our findings are quite similar to the results of the one other study in which thought disorder was assessed in adolescents using the TDI (Arboleda and Holzman, 1985). The mean Total TDI score of our psychotic patient groups varied between 14.1 and 20.8. The psychotic children studied by Arboleda and Holzman (1985) presented a more heterogeneous group of psychiatric conditions (schizophrenia, major depression, pervasive developmental disorder), but their mean score was 22.8, compared with 20.8 for our adolescent schizophrenics. Likewise, the average Total TDI score of the hospitalized nonpsychotic adolescents studied by Arboleda and Holzman (1985), 8.8,

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was very similar to that of our patients who were hospitalized with nonpsychotic conditions, 6.94. Although the mean Total TDI of our normal control group, 3.98, was similar to the range of mean Total TDI scores of adult normal controls, 5.9-9.4 (Johnston and Holzman, 1979; Hurt et al., 1983; Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987; Levy et al., 1993) it was somewhat lower than the mean (7.95) reported by Arboleda and Holzman (1985). Also, we did not find the modest, but statistically significant association between younger age and higher Total TDI score in normal children that Arboleda and Holzman (1985) reported, or the significant age effects described by Caplan (1994). It is likely that differences in the age range of the various samples of control children are responsible for both minor differences in results. Both Arboleda and Holzman (1985) and Caplan (1994) studied children in a broader age range and/or younger age groups (5-16; 7.4-12.5) than we did (12-18) which allowed age-related changes in cognitive maturation to be detected. 4.4. Thought disorder in relation to cognitive development andpsychopathology

Although adolescents without Axis I disorders and those with nonpsychotic conditions show occasional instances of cognitive slippage, the thought disturbances in these groups, as in their adult counterparts, tend to be mild in severity and to occur relatively infrequently. These mild instances of thought slippage accounted for the vast majority of the thought disorder that was found in all of the groups, again paralleling findings in adults (Johnston and Holzman, 1979; Hurt et al., 1983; Levy et al., 1993; Spohn et al., 1986). These results are also consistent with Caplan’s finding (Caplan, 1994) that more serious kinds of thought disturbance, like illogical thinking and looseness, are not typical of normal children over the age of 7, and that even schizophrenic children rarely manifest the very severe thought disorganization indicated by incoherence. Stilted use of language and mild combinatory thinking, which are among the least severe kinds of disturbances in thinking, accounted for 95% of the storable

instances of thought disorder in the normal control subjects, 74% of the thought disorder in the nonpsychotics and psychotic depressives, and 59% of the thought disorder in the schizophrenics. We agree with Weiner and Exner (1978) that little diagnostic significance can be attributed to the mere occurrence of a mildly thought disordered response when such instances are infrequent and are not accompanied by more severe kinds of thought pathology. When combinatory thinking occurred in normal subjects and nonpsychotic individuals, it was playful and frivolous, and reflected the common fantasy experiences of children: mice that fly, ducks that talk, robots that are also cars (gobots). These mild incongruities mix fantasy with reality in much the same way that cartoon characters or popular toys (i.e., transformers) adopt unrealistic attributes or fluidly change from one entity into another. Such incongruities reflect cognitive immaturity, and not psychotically disordered thought. When such combinatory thinking occurred in the psychotic adolescents, it had a more malignant quality, reflecting slippage in control of thought organization. Similar qualitative differences distinguished the stilted language of a psychiatrically healthy normal subject from the deviant verbalizations of the adolescent schizophrenic, even though storable instances of peculiar use of language occurred in both groups. In contrast to the sporadic occurrence of mild combinatory thinking and stilted use of language, the combination of frequent mildly thought disordered responses with more severe kinds of thinking disturbances (autistic logic, confabulatory thinking, neologisms, incoherence) occurs in the context of serious psychopathology. The comparatively lower rate of mildly thought disordered responses in the schizophrenic adolescents reflects the co-occurrence of more severe kinds of thought disorder in this group. This same pattern was observed in all three groups of psychiatric patients relative to the normal controls, but was most conspicuous in the schizophrenics. 4.5. Psychotropic medications

The TDI was administered to all psychiatric patients within an average of 4-5 days following

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admission to the hospital. Although only a short time elapsed between admission and testing, 60% of the schizophrenics and 50% of the psychotic depressives were receiving psychotropic medication at the time of the thought disorder assessment, and 85% of the schizophrenics and 42% of the psychotic depressives had taken antipsychotic medication prior to this hospitalization. The effect of treatment with neuroleptic medications would be to reduce the amount and severity of the thought disorder detected in the adolescents with psychotic conditions (Hurt et al., 1983; Spohn et al., 1986). This effect can be detected as quickly as 3 days after the initiation of antipsychotic drug treatment (Hurt et al., 1983), and both the schizophrenics and the psychotic depressives had a longer period of exposure at the time of the TDI (median of 5 days and 3.5 months, respectively). The elevated thought disorder of the schizophrenics and the psychotic depressives relative to the nonpsychotics and normal controls indicates that the dampening effect of medications did not elimina.te group differences in disturbances in thinking. This is not surprising, because despite prior or current neuroleptic exposure, these patients (and the adult populations in the cited studies) were in clinical states that were unstable enough to warrant hospitalization. It is likely, however, that psychotropic medications attenuated both the magnitude of the elevation in amount of thought disorder and its severity, and this may be one reason for the infrequency of responses at the 0.75 and 1.0 levels. This interpretation is consistent with the findings of Spohn et al. (1986) who showed that antipsychotic medications reduce primarily the more severe forms of thought disorder. Indeed, medicated patients in each diagnostic group had lower Total TDI scores than did unmedicated patients, and psychotic patients receiving neuroleptic drugs had lower Total TDI scores than did those who were not taking antipsychotics. These differences did not reach statistical significance, however, probably due to limited power. Power to detect group differences between schizophrenic and psychotic depressive adolescents may have been reduced by the normalizing effects of psychotropic medication. The schizophrenics had a substantially higher Total TDI score than the

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psychotic depressive patients, but the difference was not statistically significant. Although low power may also be a factor in this respect, it is noteworthy that proportionately more schizophrenics (70%) than psychotic depressives (33%) were taking antipsychotic medication. Differences in the components of the thought disorder shown by these two groups, however, were not masked. A similar pattern is found in medicated adult schizophrenic, schizo-affective manic, schizo-affective depressed, and manic patients: all psychotic groups show an elevated amount of thought disorder relative to normal controls, and although quantity of thought disorder does not distinguish among psychotic patient groups, each clinical disorder has a distinctive thought disorder profile (Johnston and Holzman, 1979; Holzman et al., 1986; Shenton et al., 1987; Solovay et al., 1987). Our results indicate that when adolescent patients are evaluated early in the course of hospitalization for an acute psychotic condition, a relatively short duration of neuroleptic drug exposure does not obscure either elevations in thought disorder or patterns of thought disorder that can contribute to differential diagnosis. 4.6. Longitudinal stability of diagnosis Inherent in the relatively short duration of illness of young adolescents is a higher degree of diagnostic instability than is associated with a more chronically ill group, on whom more extensive longitudinal data are usually available. In particular, it is possible that some of the patients who were believed to have nonschizophrenic and nonpsychotic conditions will go on to show symptoms that would result in diagnostic reassignment as the nature of the illness evolves more fully.

5. Summary

At least from the standpoint of the quantity and the qualitative characteristics of thought disorder, adolescent-onset and adult-onset schizophrenia seem to be the same disorder. The thought disorder associated with both adolescent- and adult-onset schizophrenia can be reliably identified and

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characterized, even in patients who have had recent exposure to neuroleptic drugs or who are currently medicated.

Acknowledgment

This work was supported in part by NIMH grants ROl MH49487, ROl MH31340, PO1 MH3 1154, a Predoctoral Research Fellowship (F31 MH09947) and a Stanley Foundation Predoctoral Research Fellowship. The authors thank the participants in the study and the staffs of their inpatient units for their collaboration in completing this work, and Drs. Rochelle Caplan, Philip Holzman and Steven Matthysse for critically reviewing the manuscript.

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