Regional cerebral glucose metabolism in first episode schizophrenic patients with and without auditory verbal hallucinations

Abstract

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Objectives: Auditory verbal hallucinations (AVH) are a core symptom of schizophrenia. The study was conducted in a homogeneous group of schizophrenic patients to assess whether the presence or absence of AVH is associated with different regional cerebral glucose metabolism patterns.

Methods: Sixteen dextral antipsychotic-naïve first-episode DSM-IV schizophrenic patients were examined during resting state using [18F]fluoro-deoxyglucose PET. Clinical assessment was performed with the Positive and Negative Syndrome Scale. The frequency and form of AVH were rated just before PET acquisition using the items from PSYRATS scale. PET scans were acquired using an Advanced-Nxi Scanner (GE). SPM5 was employed to analyze statistical differences. A basal comparison of schizophrenic patients with AVH (n=9; mean age of 25,3 [SD=3,9] years; 5 females, and 4 males) versus patients without AVH (n=7; mean age of 26,8 [SD=3,4] years; 4 females, and 3 males) was made using a two-sample t-test.

Results: Patients with AVH had significantly higher metabolic rate in the left superior and middle temporal cortices, the superior medial frontal cortex and the left caudate nucleus (p≤0.005, corrected for multiple comparisons).

Conclusions: AVH in schizophrenia may be mediated by an alteration of neural pathways responsible for normal language function, including those involved in the generation of inner speech and the ones implicated in the perception of external language. Moreover, our findings also suggest an important role of the dominant caudate nucleus in the pathophysiology of AVH, which could be related to the bilingual condition of our sample according to recent studies.

Research Support: Supported by funding from Janssen-Cilag and Fundació Marató TV3.