Frontal and nonfrontal cortical thickness linked to insight in FEP patients
MedWire News: Results from a Canadian study suggest that reduced cortical thickness in both the frontal and nonfrontal cortices is associated with poor insight in first-episode psychosis patients.
"A substantial proportion of people with psychosis demonstrate lack of insight into their illness, including difficulty recognizing the pathological nature of their symptoms and acknowledging the need for treatment," observe Martin Lepage (Douglas Mental Health University Institute, Verdun, Quebec) and team.
They add: "Through conceptualizing poor insight in psychotic disorders as a form of anosognosia (neurological deficit), frontal lobe dysfunction is often ascribed a vital role in its pathogenesis. Whether non-frontal brain regions are important for insight remains to be investigated."
In the current study, the researchers examined the relationship between insight and cortical thickness in all regions among 79 patients, aged 14-30 years, with either affective or non-affective first-episode psychosis.
Cortical thickness was assessed using magnetic resonance imaging, and voxel-based morphometry (VBM) was used to assess gray matter density. Awareness of illness and awareness of treatment need were evaluated using the Scale for Assessment of Unawareness of Mental Disorder, with items rated on a five point scale from 1 (aware) to 5 (unaware).
The researchers found that mean awareness of illness scores were significantly and inversely associated with cortical thickness.
Specifically, poorer awareness of illness was significantly associated with reduced thickness in left middle frontal and inferior temporal gyri, while poorer awareness of treatment need and efficacy was associated with reduced cortical thickness in left medial frontal gyrus, precuneus and temporal gyri.
The researchers found no significant association between gray matter density and either awareness of mental disorder scores or awareness of treatment need/efficacy scores. Limiting the VBM analysis to patients with non-affective psychosis did not influence the results.
Lepage and team conclude in the Journal of Psychiatric Research: "The results confirm predictions derived from the anosognosia/neuropsychology account and assert that regional thickness in frontal cortex is associated with awareness of illness in the early phase of psychosis."
They add: "The fact that prominent thickness reductions emerged in non-frontal regions of the brain in parietal and temporal cortices for both awareness of illness and awareness of treatment need and efficacy suggests that the neural signature of insight involves a network of brain structures, and not only the frontal lobes as previously suggested."
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By Mark Cowen