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Syntax and semantics in schizophrenic formal thought disorder: A study using the single case approach
66
impaired in their use of linguistic context 'online' to process speech. In the present study, we investigated how the ability to use linguistic context varied with severity of thought disorder at different points in time within the same patients. Twentyseven schizophrenic patients performed an online wordmonitoring task m which we measured reaction times to recognise target words in normal sentences (e.g. "... the man played the guitar') and linguistically-anomalous sentences (e.g. "... the man drank the guitar'), on four separate occasions separated by an average interval of 15 days. Thought disorder and overall psychopathology were rated on each occasion. Sensitivity to linguistic context was defined operationally as the progressive increase (trend) in reaction time to recognise target words in normal sentences, and in pragmatically-, semantically- and syntactically-violated sentences, in that order. Using a purely "within-subject" method of analysis over the four testing sessions, we showed that, in the group as a whole, severity of thought disorder, but not overall psychopathology, varied inversely with sensitivity to linguistic context. These findings were supported by our examination of the performance of those individual patients showing marked variation in severity of thought disorder over testing sessions: these selected patients were least sensitive to linguistic anomalies when they were most thought-disordered. We conclude that an impairment in using linguistic context to process speech represents a state, rather than a trait, marker of schizophrenic thought disorder.
S E M A N T I C FACILITATION A N D INTERFERENCE: B E H A V I O U R A L A N D ELECTROPHYSIOLOGICAL E V I D E N C E FOR A DEFICIT IN SCHIZOPHRENIA G . R . K u p e r b e r g l, R . M . M u r r a y ~, C.D. Binnie 2, H.B. A n d r e w s 3
~lnstitute ol'Psychiatrv, DeO'espigny Park, Denmark Hill, London SE5 8AF, UK." 2Kings College Ho,wital. Denmark Hill, London SE5 9 RS, UK," 3Leicestershire Mental Health Service, Leicester LE4 9HA. UK Behavioural and electrophysiological studies suggest that deficits in lexical-semantic processing may underlie language disorders in schizophrenia. We investigated the ability of schizophrenics to use the semantic relationship between one wordpair to affect the processing of a second word-pair under three different conditions: facilitatory, interference, and neutral. In the facilitatory condition, words comprising the first and second pairs were highly associated (e.g. hand nail; nail finger). In the interference condition, the relationship between words of the first pair was unrelated to that of the second (e.g. hammer nail; nail finger). In the neutral condition, the words of the first word-pair were unrelated (e.g. tea nail; nail finger). Experimental trials were randomly mixed amongst fillers in which words comprising the second pair were unrelated. Behm,ioural data." In comparison with the neutral condition, controls were faster in the facilitatory condition but slower in the interference condition, to decide whether or not the words
of the second pair were related. Schizophrenics showed significantly smaller reaction time differences. Eh'ctrophysiological data." In controls, the amplitude of two components thought to reflect online semantic processing N400 and subsequent 'late positive component' (LPC) was greater in the interference than the faciliatory condition. In schizophrenics, although the amplitude of the N400 itself showed the same pattern as controls, the LPC failed to show this effect and, at some electrode sites, showed a reversed pattern. We conclude that schizophrenic patients are impaired in using semantic context, but that this deficit occurs at a relatively late stage of lexical processing.
USE OF L A N G U A G E IN PRE-SCHIZOPHRENIC C H I L D R E N E. Leinonen x, D.J. Done x, T.J. Crow-" 1Department q["Lhtguistics. University q/' Her(fi)rdshire, ~t(lbrd WD2 8AT. UK: 2 p o w I c , Universi O' q/'OxJord, UK Communication problems are well-documented in adult schizophrenia and may well predate the onset of symptoms. We have analysed essays written by 11 year old children in a national UK birth cohort (NCDS) who later developed schizophrenia by age 28 years. Control subjects were matched for IQ, social class and region of domicile. Essays were analysed for cohesion (i.e. semantic links between sentences developed by Halliday and Hasan 1976), story coherence (i.e. how the themes of a written narrative fit together) and use of evaluation (i.e. linguistic forms which indicate the narrator's metacognitive abilities and awareness of the listener's perspective). No significant differences were found between the pre-schizophrenic children and well matched controls on any of these measures of language use. However the same pre-schizophrenic subjects were considered by their teachers to have significantly more maladjusted social behaviour, with 50% being reported to have poor general knowledge and 40% poor oral ability, both of these findings being highly significant. These results suggest that language per se might not be impaired in pre-schizophrenic children. We conjecture that in social situations, preschizophrenic children will frequently manifest more maladjusted interpersonal behaviour and as well as impaired, or abnormal ability in verbal and non-verbal communication.
S Y N T A X A N D SEMANTICS IN SCHIZOPHRENIC F O R M A L T H O U G H T DISORDER: A S T U D Y U S I N G THE SINGLE CASE APPROACH T . M . Oh, R.A. M c C a r t h y , P.J. M c K e n n a
D~7~artment of Exlwrimental P.s3'choh~g~v, UniversiO" qf Camhridge, Downing St.. Cambridge CB2 3EB, UK The relationship between language disorder and formal thought disorder (FTD) in schizophrenia remains unclear.
67
Following Chaika, we applied the single case study approach to examine the contribution of neurolinguistic abnormalities to the phenomenon. Five patients meeting RDC criteria |br schizophrenia with severe FTD were compared with five non-thought disordered schizophrenics (NTD). The intellectual status of patients in both groups ranged from intact to very impaired. Comprehension of syntax and semantics was assessed with tests from the PALPA (Psycholinguistic Assessment of Language Processing in Aphasia). Free speech samples were collected and analysed using Thomas et al.'s Brief Syntactic Analysis (BSA). Performance on PALPA tests of syntax and semantic comprehension reflected intellectual status but not presence of formal thought disorder. For expressive speech, three BSA variables were investigated: deviance (syntactic and semantic errors), syntactic complexity, and dysfluencies. There were twice as many deviant sentences in FTD speech compared to NTD speech. This difference was accounted for by increased semantic errors in the FTD patients; syntactic errors were equally prevalent in both groups. No differences emerged for complexity and dysfluency counts. None of the expressive abnormalities were related to presence of general intellectual impairment. Our study suggests that problems with comprehension of syntax and semantics in schizophrenia are a function of intellectual impairment, not of presence of formal thought disorder. Expressed speech in FTD patients is neither less fluent nor less complex compared to NTD patients, but does seem to contain more semantic errors which occur across the range of intellectual levels.
NEURAL
CORRELATES
OF PROCESSING
BRITISH SIGN LANGUAGE DEAF
(BSL) IN THE
D. R o b e r t s o n , A. Thacker, A.S. David, N. Kitson, R.S.J. Frackowiak, C.D. Frith, P.K. McGuire
Department qI' Psychologieal Medicine, Institute q[' Psychiato'. KinL,'s College School o[' Medicine, London SE5 8A F, UK Background: Schizophrenics who are profoundly prelingually deaf (PPD) and use BSL may experience hallucinations they describe as 'voices'. The neurobiological basis of these is unknown. Regional cerebral blood flow (rCBF) is increased in left inferior frontal regions in hearing people during auditory hallucinations areas activated when subjects perform inner speech tasks. Therefore, we used PET to test the hypothesis that brain regions involved in processing BSL are similar to those involved in processing verbal language. Method: Five PPD BSL men performed three tasks; passive viewing of single BSL signs, passive viewing of single orthographically regular pseudosigns, and internal generation of BSL sentences cued by a signed attribute ('inner sign'). The tasks made different semantic, phonological and generative
demands, rCBF was measured after intravenous infusion of H2~50 (10mlmin-~: 55Mbqml 1), using a CTI 953B PET scanner. Images were reconstructed by three dimensional filtered back projection with a ramp filter; image resolution was approximately 6 x 6 x6 FWHM. Data were analysed using Statistical Parametric Mapping (SPM95). Results: Processing signs activated the superior temporal lobes relative to processing pseudosigns. Pseudosigns activated the left insula and left inferior parietal regions relative to processing signs. Compared to viewing signs, performing 'inner sign' activated the left inferior frontal region. Conclusion." The brain regions involved in processing BSL are similar to those involved in verbal language, suggesting that brain regions mediating linguistic processing do not depend on early linguistic experience or upon linguistic modality. This reinforces the notion that the left cerebral hemisphere is intrinsically specialised for language. We hypotbesise that "voices" in PPD people with schizophrenia are related to abnormal function of the left inferior frontal lobe.
SEMANTIC
MEMORY
CORRELATES
IMPAIRMENT
WITH THOUGHT
DISORDER
M. Vassallo, T.J. Crow, E. Leinonan
POWIC, Department q/ P.~vehiatry, University q/ O'~[~rd, Warn~[brd Ho,v~ital. Headington, O~,{[brd0)(3 7JX, UK Semantic memory impairment has been found in schizophrenia. The object of this study was to examine the relationship between semantic memory dysfunction and thought disorder in patients with psychotic illness. The subjects included 11 controls and 23 subjects with a psychotic illness of 2 years or more duration ( 17 with schizophrenia, 4 with bipolar affective disorder and 2 with a schizoaffective illness). Cognition and premorbid intelligence were rated on the Mini Mental State Examination and National Adult Reading Test (NART). Semantic memory function was rated on the Hodges Semantic Memory Test Battery; thought disorder was rated on the Clinical Language Disorder Rating Scale (CLANG). Correlation was found between the ratings for thought disorder and semantic memory impairment throughout the range of tests used with a strong correlation between thought disorder and the proportion of semantic errors made (Spearman's rho, 0.8269, one-tailed, p <0.001 ). Not only did definitions testing and degree of thought disorder correlate, but the number of specific items produced per definition showed a close correlation with thought disorder, even when variations in cognition and premorbid intelligence were accounted for. Thus, this study suggests that semantic memory dysfunction might have a role in the genesis of the distinctive language abnormalities that comprise thought disorder.
impaired in their use of linguistic context 'online' to process speech. In the present study, we investigated how the ability to use linguistic context varied with severity of thought disorder at different points in time within the same patients. Twentyseven schizophrenic patients performed an online wordmonitoring task m which we measured reaction times to recognise target words in normal sentences (e.g. "... the man played the guitar') and linguistically-anomalous sentences (e.g. "... the man drank the guitar'), on four separate occasions separated by an average interval of 15 days. Thought disorder and overall psychopathology were rated on each occasion. Sensitivity to linguistic context was defined operationally as the progressive increase (trend) in reaction time to recognise target words in normal sentences, and in pragmatically-, semantically- and syntactically-violated sentences, in that order. Using a purely "within-subject" method of analysis over the four testing sessions, we showed that, in the group as a whole, severity of thought disorder, but not overall psychopathology, varied inversely with sensitivity to linguistic context. These findings were supported by our examination of the performance of those individual patients showing marked variation in severity of thought disorder over testing sessions: these selected patients were least sensitive to linguistic anomalies when they were most thought-disordered. We conclude that an impairment in using linguistic context to process speech represents a state, rather than a trait, marker of schizophrenic thought disorder.
S E M A N T I C FACILITATION A N D INTERFERENCE: B E H A V I O U R A L A N D ELECTROPHYSIOLOGICAL E V I D E N C E FOR A DEFICIT IN SCHIZOPHRENIA G . R . K u p e r b e r g l, R . M . M u r r a y ~, C.D. Binnie 2, H.B. A n d r e w s 3
~lnstitute ol'Psychiatrv, DeO'espigny Park, Denmark Hill, London SE5 8AF, UK." 2Kings College Ho,wital. Denmark Hill, London SE5 9 RS, UK," 3Leicestershire Mental Health Service, Leicester LE4 9HA. UK Behavioural and electrophysiological studies suggest that deficits in lexical-semantic processing may underlie language disorders in schizophrenia. We investigated the ability of schizophrenics to use the semantic relationship between one wordpair to affect the processing of a second word-pair under three different conditions: facilitatory, interference, and neutral. In the facilitatory condition, words comprising the first and second pairs were highly associated (e.g. hand nail; nail finger). In the interference condition, the relationship between words of the first pair was unrelated to that of the second (e.g. hammer nail; nail finger). In the neutral condition, the words of the first word-pair were unrelated (e.g. tea nail; nail finger). Experimental trials were randomly mixed amongst fillers in which words comprising the second pair were unrelated. Behm,ioural data." In comparison with the neutral condition, controls were faster in the facilitatory condition but slower in the interference condition, to decide whether or not the words
of the second pair were related. Schizophrenics showed significantly smaller reaction time differences. Eh'ctrophysiological data." In controls, the amplitude of two components thought to reflect online semantic processing N400 and subsequent 'late positive component' (LPC) was greater in the interference than the faciliatory condition. In schizophrenics, although the amplitude of the N400 itself showed the same pattern as controls, the LPC failed to show this effect and, at some electrode sites, showed a reversed pattern. We conclude that schizophrenic patients are impaired in using semantic context, but that this deficit occurs at a relatively late stage of lexical processing.
USE OF L A N G U A G E IN PRE-SCHIZOPHRENIC C H I L D R E N E. Leinonen x, D.J. Done x, T.J. Crow-" 1Department q["Lhtguistics. University q/' Her(fi)rdshire, ~t(lbrd WD2 8AT. UK: 2 p o w I c , Universi O' q/'OxJord, UK Communication problems are well-documented in adult schizophrenia and may well predate the onset of symptoms. We have analysed essays written by 11 year old children in a national UK birth cohort (NCDS) who later developed schizophrenia by age 28 years. Control subjects were matched for IQ, social class and region of domicile. Essays were analysed for cohesion (i.e. semantic links between sentences developed by Halliday and Hasan 1976), story coherence (i.e. how the themes of a written narrative fit together) and use of evaluation (i.e. linguistic forms which indicate the narrator's metacognitive abilities and awareness of the listener's perspective). No significant differences were found between the pre-schizophrenic children and well matched controls on any of these measures of language use. However the same pre-schizophrenic subjects were considered by their teachers to have significantly more maladjusted social behaviour, with 50% being reported to have poor general knowledge and 40% poor oral ability, both of these findings being highly significant. These results suggest that language per se might not be impaired in pre-schizophrenic children. We conjecture that in social situations, preschizophrenic children will frequently manifest more maladjusted interpersonal behaviour and as well as impaired, or abnormal ability in verbal and non-verbal communication.
S Y N T A X A N D SEMANTICS IN SCHIZOPHRENIC F O R M A L T H O U G H T DISORDER: A S T U D Y U S I N G THE SINGLE CASE APPROACH T . M . Oh, R.A. M c C a r t h y , P.J. M c K e n n a
D~7~artment of Exlwrimental P.s3'choh~g~v, UniversiO" qf Camhridge, Downing St.. Cambridge CB2 3EB, UK The relationship between language disorder and formal thought disorder (FTD) in schizophrenia remains unclear.
67
Following Chaika, we applied the single case study approach to examine the contribution of neurolinguistic abnormalities to the phenomenon. Five patients meeting RDC criteria |br schizophrenia with severe FTD were compared with five non-thought disordered schizophrenics (NTD). The intellectual status of patients in both groups ranged from intact to very impaired. Comprehension of syntax and semantics was assessed with tests from the PALPA (Psycholinguistic Assessment of Language Processing in Aphasia). Free speech samples were collected and analysed using Thomas et al.'s Brief Syntactic Analysis (BSA). Performance on PALPA tests of syntax and semantic comprehension reflected intellectual status but not presence of formal thought disorder. For expressive speech, three BSA variables were investigated: deviance (syntactic and semantic errors), syntactic complexity, and dysfluencies. There were twice as many deviant sentences in FTD speech compared to NTD speech. This difference was accounted for by increased semantic errors in the FTD patients; syntactic errors were equally prevalent in both groups. No differences emerged for complexity and dysfluency counts. None of the expressive abnormalities were related to presence of general intellectual impairment. Our study suggests that problems with comprehension of syntax and semantics in schizophrenia are a function of intellectual impairment, not of presence of formal thought disorder. Expressed speech in FTD patients is neither less fluent nor less complex compared to NTD patients, but does seem to contain more semantic errors which occur across the range of intellectual levels.
NEURAL
CORRELATES
OF PROCESSING
BRITISH SIGN LANGUAGE DEAF
(BSL) IN THE
D. R o b e r t s o n , A. Thacker, A.S. David, N. Kitson, R.S.J. Frackowiak, C.D. Frith, P.K. McGuire
Department qI' Psychologieal Medicine, Institute q[' Psychiato'. KinL,'s College School o[' Medicine, London SE5 8A F, UK Background: Schizophrenics who are profoundly prelingually deaf (PPD) and use BSL may experience hallucinations they describe as 'voices'. The neurobiological basis of these is unknown. Regional cerebral blood flow (rCBF) is increased in left inferior frontal regions in hearing people during auditory hallucinations areas activated when subjects perform inner speech tasks. Therefore, we used PET to test the hypothesis that brain regions involved in processing BSL are similar to those involved in processing verbal language. Method: Five PPD BSL men performed three tasks; passive viewing of single BSL signs, passive viewing of single orthographically regular pseudosigns, and internal generation of BSL sentences cued by a signed attribute ('inner sign'). The tasks made different semantic, phonological and generative
demands, rCBF was measured after intravenous infusion of H2~50 (10mlmin-~: 55Mbqml 1), using a CTI 953B PET scanner. Images were reconstructed by three dimensional filtered back projection with a ramp filter; image resolution was approximately 6 x 6 x6 FWHM. Data were analysed using Statistical Parametric Mapping (SPM95). Results: Processing signs activated the superior temporal lobes relative to processing pseudosigns. Pseudosigns activated the left insula and left inferior parietal regions relative to processing signs. Compared to viewing signs, performing 'inner sign' activated the left inferior frontal region. Conclusion." The brain regions involved in processing BSL are similar to those involved in verbal language, suggesting that brain regions mediating linguistic processing do not depend on early linguistic experience or upon linguistic modality. This reinforces the notion that the left cerebral hemisphere is intrinsically specialised for language. We hypotbesise that "voices" in PPD people with schizophrenia are related to abnormal function of the left inferior frontal lobe.
SEMANTIC
MEMORY
CORRELATES
IMPAIRMENT
WITH THOUGHT
DISORDER
M. Vassallo, T.J. Crow, E. Leinonan
POWIC, Department q/ P.~vehiatry, University q/ O'~[~rd, Warn~[brd Ho,v~ital. Headington, O~,{[brd0)(3 7JX, UK Semantic memory impairment has been found in schizophrenia. The object of this study was to examine the relationship between semantic memory dysfunction and thought disorder in patients with psychotic illness. The subjects included 11 controls and 23 subjects with a psychotic illness of 2 years or more duration ( 17 with schizophrenia, 4 with bipolar affective disorder and 2 with a schizoaffective illness). Cognition and premorbid intelligence were rated on the Mini Mental State Examination and National Adult Reading Test (NART). Semantic memory function was rated on the Hodges Semantic Memory Test Battery; thought disorder was rated on the Clinical Language Disorder Rating Scale (CLANG). Correlation was found between the ratings for thought disorder and semantic memory impairment throughout the range of tests used with a strong correlation between thought disorder and the proportion of semantic errors made (Spearman's rho, 0.8269, one-tailed, p <0.001 ). Not only did definitions testing and degree of thought disorder correlate, but the number of specific items produced per definition showed a close correlation with thought disorder, even when variations in cognition and premorbid intelligence were accounted for. Thus, this study suggests that semantic memory dysfunction might have a role in the genesis of the distinctive language abnormalities that comprise thought disorder.