Association between prefrontal N-acetylaspartate and insight in psychotic disorders

Insight is impaired in most patients with psychosis and has been associated with poorer prognosis. The exact neural basis of impaired insight is still unknown, but it may involve disrupted prefrontal neural connectivity. Numerous studies have indeed found white matter (WM) abnormalities in psychosis. The association between prefrontal WM abnormalities and insight has not been studied yet by means of proton magnetic resonance spectroscopy (¹H-MRS). ¹H-MRS can be used to measure N-acetylaspartate (NAA), which is considered to be a marker of neuronal integrity. We measured insight with the Birchwood Insight Scale (BIS) as well as item G12 of the Positive and Negative Syndrome Scale (PANSS) in 88 patients with psychosis. Prefrontal WM concentrations of NAA and ratios of NAA to creatine (Cr) were assessed with ¹H-MRS. Nonparametric partial correlational analyses were conducted between NAA concentrations and insight controlling for illness duration, standardized antipsychotic dose, symptom scores, voxel grey matter content and voxel cerebrospinal fluid content. We found a significant correlation between reduced NAA/Cr ratios and poorer insight as measured with the BIS, which remained significant after additional correction for full width at half maximum, signal/noise and age. This is the first study reporting a relationship between lower prefrontal concentrations of a marker of neuronal integrity and impaired insight, providing further evidence that prefrontal pathology may play an important role in impaired insight in psychosis. This may be explained by the involvement of the prefrontal cortex in several executive and metacognitive functions, such as cognitive flexibility and perspective taking.

Implicit and explicit self-related processing in relation to insight in patients with schizophrenia

INTRODUCTION

Self-related processing (SRP) has been associated with clinical and cognitive insight. We investigated the relationship between implicit SRP (ISRP) and explicit SRP (ESRP) and insight. We first hypothesised that impaired insight is associated with the extent to which implicit feedback is incorporated in the self-image and subsequently influences behaviour. Second, we hypothesised that impaired insight is related to the way patients handle explicit feedback and use it to guide subsequent behaviour, therefore we expected to find a positive relationship between level of insight and the explicit self-related processing task.

METHODS

Thirty-four schizophrenia patients and 23 healthy controls participated in the study. Patients were assessed with the Schedule for the Assessment of Insight-Expanded and the Beck Cognitive Insight Scale. ISRP was measured using a working memory two-back priming task. ESRP was measured with an adapted version of the Wisconsin Card Sorting Task where patients received explicit feedback on their performance.

RESULTS

Cognitive insight, but not clinical insight, was positively associated with ISRP after implicit positive cues. Both clinical and cognitive insight were positively associated with the ability to adjust performance upon receiving explicit feedback, though cognitive insight was more strongly associated with overall task performance.

CONCLUSIONS

Priming with positive cues improved performance on a working memory task in patients with good cognitive insight, but worsened performance in patients with impaired cognitive insight. Furthermore, our findings suggest that the ability to adequately use feedback may be a specific capacity that is related to insight.

Insight in schizophrenia: involvement of self-reflection networks?

BACKGROUND

Impaired insight is a common feature in psychosis and an important predictor of variables such as functional outcome, prognosis, and treatment adherence. A cognitive process that may underlie insight in psychosis is self-reflection, or the conscious evaluation of one's traits and characteristics. The current study aims to investigate the neural correlates of self-reflective processing and its relationship with insight in schizophrenia.

METHODS

Forty-seven schizophrenia patients and 21 healthy controls performed a self-reflection task in a functional magnetic resonance imaging (fMRI) scanner. The tasks comprised a self-reflection, close other-reflection, and a semantic (baseline) condition. Insight scores were obtained with the Schedule of Assessment of Insight Expanded. In addition, cognitive insight scores were obtained (Beck Cognitive Insight Scale [BCIS]).

RESULTS

Schizophrenia patients demonstrated less activation in the posterior cingulate cortex in the self- and other-reflection conditions and less activation in the precuneus in the other-reflection condition compared with healthy controls. Better insight was associated with greater response in the inferior frontal gyrus, anterior insula, and inferior parietal lobule during self-reflection. In addition, better cognitive insight was associated with higher activation in ventromedial prefrontal cortex during self-reflection.

CONCLUSION

In the current study, evidence for a relationship between self-reflection and insight in patients with schizophrenia was found in brain areas related to self-reflection, self/other distinction and source attribution. The findings support the rationale for a treatment that is currently under evaluation, which attempts to increase insight by enhancing self-reflection.