Cortical volume abnormalities in schizophrenia: Correlations with symptoms and cognitive impairment.

BACKGROUND: Schizophrenic symptoms are known to segregate into reality distortion, negative and disorganization syndromes, but the correlates of these syndromes with regional brain structural change are not well established. Cognitive impairment is a further clinical feature of schizophrenia, whose brain structural correlates are the subject of conflicting findings. METHODS: 165 patients with schizophrenia were rated for symptoms using the PANSS, and cognitive impairment was indexed by estimated premorbid-current IQ discrepancy. Cortical volume was measured using surface-based morphometry in the patients and in 50 healthy controls. Correlations between clinical and cognitive measures and cortical volume were examined using whole-brain FreeSurfer tools. RESULTS: No clusters of volume reduction were seen associated with reality distortion or disorganization. Negative symptom scores showed a significant inverse correlation with volume in a small cluster in the left medial orbitofrontal gyrus. Larger estimated premorbid-current IQ discrepancies were associated with clusters of reduced cortical volume in the left precentral gyrus and the left temporal lobe. The cluster of association with negative symptoms disappeared when estimated premorbid-current IQ discrepancy was controlled for. CONCLUSIONS: This study does not provide support for an association between brain structural abnormality and reality distortion or disorganization syndromes in schizophrenia. The cluster of volume reduction found in the left medial orbitofrontal cortex correlated with negative symptoms may have reflected the association between this class of symptoms and cognitive impairment. The study adds to existing findings of an association between cognitive impairment and brain structural changes in the disorder.

The linguistic signature of hallucinated voice talk in schizophrenia.

Very few studies have investigated the formal linguistic aspects of auditory verbal hallucinations (AVHs), though speech is a defining aspect of AVHs. Hallucinated speech heard by 19 patients with schizophrenia and highly frequent voices was obtained online, as and when they spoke, and annotated for pre-selected linguistic variables. Results showed that, consistently across the sample, (i) the grammatical first Person was significantly less represented than both second and third person, and often absent altogether; (ii) overwhelmingly, isolated clauses with no grammatical connectivity (parataxis) were produced, as compared with subordinations, coordinations, and adjunctions; (iii) in all participants except one, virtually no noun phrases (NPs) were anaphoric ones, back-referring to previous NPs, illustrating again a lack of connectivity across utterances. (vi) Sentence-level content was largely personal rather than impersonal, and in impersonal utterances, it was generally vague. (v) Formal syntactic errors were consistently nearly absent, as were semantic level errors such as paraphasias. Voice talk was not generally stereotyped. These results indicate that, despite a certain amount of individual variation, there is a distinctive linguistic profile to voice speech, which constrains theories of AVHs and their neurocognitive basis.