The metabolic basis of cognitive insight in psychosis: A positron emission tomography study

Abstract

The purpose of this study was to investigate the relationship between cognitive insight and cerebral metabolism in patients suffering from psychosis. The Beck Cognitive Insight Scale (BCIS) was administered to 63 patients with psychosis undergoing Positron Emission Tomography investigation. The sample was divided into two groups considering the BCIS score. Data were analyzed using Statistical Parametric Mapping. Results: patients with low insight, compared to those with high insight, showed decreased metabolism in the right fusiform gyrus, left precuneus, superior temporal gyrus and insula bilaterally, as well as increased metabolism in the left orbito-frontal gyrus (all p<0.005). Our results suggest that reduced posterior (occipito-temporo-insulo-parietal) and increased anterior (orbitofrontal) cerebral metabolism may sustain low cognitive insight in psychosis.

The metabolic basis of psychosis in bipolar disorder: A positron emission tomography study

“…35 Moreover, a previous PET study from our group found metabolic alterations in this area in relation to insight towards the disease in a sample of psychotic BD patients and patients with schizophrenia. 36 Taken together, our results further suggested that alterations in regions associated with emotional processing may be considered a key feature of BD, as consistently reported by previous imaging studies in mood disorders. 37 However, although deficits in temporal cortex and insula are extensively found in BD, the role of occipital cortex in this disabling disorder is still not fully understood.…”

“…Also, a recent MRI study showed that a history of psychosis in BD patients was associated with decreased GM volume in fusiform cortex . Similarly, a recent PET study carried out by our research group found that in psychotic BD subjects the presence of low insight of disease was associated with decreased metabolism in the fusiform gyrus along with other brain areas, such as precuneus, superior temporal gyrus and insula …”

“…sad faces) . Moreover, a previous PET study from our group found metabolic alterations in this area in relation to insight towards the disease in a sample of psychotic BD patients and patients with schizophrenia …”

“…This is because psychotic and paranoid patients present an altered salience and therefore utilize contextual information inappropriately, inducing incorrect social inferences and quantitatively “over‐generating” hypotheses or “over‐attributing” significance . Therefore, it seems plausible that brain structures involved in Theory of Mind, including the fusiform gyrus might overlap with areas associated with psychotic disorders, including BD . However, future studies are warranted to corroborate this hypothesis.…”

“…41 Similarly, a recent PET study carried out by our research group found that in psychotic BD subjects the presence of low insight of disease was associated with decreased metabolism in the fusiform gyrus along with other brain areas, such as precuneus, superior temporal gyrus and insula. 36 Interestingly, from a functional perspective, the fusiform gyrus is thought to be associated with face recognition 42 and it has been reported to be also involved in Theory of Mind abilities, often impaired in psychotic illnesses. 43 Specifically, for the Theory of Mind, it has been reported that alterations in these abilities and psychotic features are deeply intertwined.…”