Voxel-based magnetic resonance imaging investigation of poor and preserved clinical insight in people with schizophrenia

Abstract

Aim: To define regional grey-matter abnormalities in schizophrenia patients with poor insight (Insight(-)), relative to patients with preserved clinical insight (Insight(+)), and healthy controls.

Methods: Forty stable schizophrenia outpatients (20 Insight(-) and 20 Insight(+)) and 20 healthy controls underwent whole brain magnetic resonance imaging (MRI). Insight in all patients was assessed using the Birchwood Insight Scale (BIS; a self-report measure). The two patient groups were pre-selected to match on most clinical and demographic parameters but, by design, they had markedly distinct BIS scores. Voxel-based morphometry employed in SPM8 was used to examine group differences in grey matter volumes across the whole brain.

Results: The three participant groups were comparable in age [F(2,57) = 0.34, P = 0.71] and the patient groups did not differ in age at illness onset [t(38) = 0.87, P = 0.39]. Insight(-) and Insight(+) patient groups also did not differ in symptoms on the Positive and Negative Syndromes scale (PANSS): Positive symptoms [t(38) = 0.58, P = 0.57], negative symptoms [t(38) = 0.61, P = 0.55], general psychopathology [t(38) = 1.30, P = 0.20] and total PANSS scores [t(38) = 0.21, P = 0.84]. The two patient groups, as expected, varied significantly in the level of BIS-assessed insight [t(38) = 12.11, P < 0.001]. MRI results revealed lower fronto-temporal, parahippocampal, occipital and cerebellar grey matter volumes in Insight(-) patients, relative to Insight(+) patients and healthy controls (for all clusters, family-wise error corrected P < 0.05). Insight(+) patient and healthy controls did not differ significantly (P > 0.20) from each other.

Conclusion: Our findings demonstrate a clear association between poor clinical insight and smaller fronto-temporal, occipital and cerebellar grey matter volumes in stable long-term schizophrenia patients.

Keywords: Birchwood insight scale; Fronto-temporal; Grey matter volumes; Insight; Neural networks; Psychosis.

Figure 1

Images showing regions of decreased grey matter volume in the impaired insight patient group, relative to the preserved insight patient and healthy controls (maps thresholded at P = 0.005; left = right).