بینشی در بیماران مبتلا به اسکیزوفرنیا: ارتباط به علائم و عملکرد نوروفیزیولوژیک

Objective Lack of insight into illness has long been recognized as a central characteristic of schizophrenia. Although recent theories have emphasized neurocognitive dysfunction as a central impairment in schizophrenia it remains unclear whether the lack of insight in schizophrenia is more strongly associated with measures of symptom severity or neuropsychological dysfunction. Methods Seventy-four consecutive inpatients with chronic schizophrenia were enrolled in a cross-sectional study. All subjects were assessed with the Positive and Negative Syndrome Scale (PANSS, five-factor model), the Insight and Treatment Attitudes Questionnaire (ITAQ), and the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB). Bivariate association and multiple linear regression analyses were used to investigate the relationship between insight and both symptoms and neurocognition. Results On bivariate correlation, the positive, negative, disorganized and excited factors of the PANSS showed a negative correlation with insight but there was no significant association between the MCCB total score or any component subscale and insight. Multiple regression analysis showed that positive symptoms, disorganized/concrete symptoms and excited symptoms contributed to awareness of mental illness; positive and disorganized/concrete symptoms were significant contributors to awareness of the need for treatment; but there were no significant associations with the MCCB. Conclusions Insight in this sample of patients with chronic schizophrenia is significantly associated with clinical symptoms but not with neuropsychological functioning.

Poor insight, or lack of awareness of one's illness, is a common symptom among patients with schizophrenia. The World Health Organization (WHO) International Pilot Study of Schizophrenia in different cultures found that ‘lack of insight’ was an almost invariable feature of acute and chronic schizophrenia, which found that 50–80% of patients lacked, either partially or totally, insight into their mental disorder (Carpenter and Bartko, 1973). Poor insight in schizophrenia has been found to be associated with poor medication compliance (McEvoy et al., 1989, Kemp and David, 1996, Sanz et al., 1998, Pini et al., 2001, Buckley et al., 2007 and Lincoln et al., 2007), poor social and interpersonal functioning (Lysaker et al., 1998 and Pyne et al., 2001), and a generally poor prognosis (Amador et al., 1993 and Schwartz, 1998), as well as with higher risk of relapse and readmission (David et al., 1995 and Drake et al., 2007). Poor insight may also be associated with co-morbid depression, hopelessness, low self-esteem (Karow and Pajonk, 2006, Cooke et al., 2007, Mohamed et al., 2009 and Staring et al., 2009) and a poor quality of life (Pyne et al., 2001 and Schwartz, 2001). Over the past decade there has been an increase in research on the correlates and consequences of poor insight, but its etiology remains poorly understood and the primary approach to deepening our understanding of it has been to further evaluate various correlates of lack of insight. This research has focused on two principal types of measure: clinical symptom measures and neuropsychological measures. Clinical measures address the possibility that poor insight is a primary symptom of the illness of schizophrenia itself (Collins et al., 1997), intimately linked with other symptoms like delusions and hallucinations. Studies that have examined the relationship between insight and symptoms in schizophrenia have demonstrated significant negative correlations between insight and the severity of positive symptoms (Amador et al., 1993 and Mintz et al., 2003) and/or negative symptoms (Carroll et al., 1999, Smith et al., 2000, Mintz et al., 2003 and Mingrone et al., 2013). Some studies have also noted a negative relationship, more specifically, between symptoms of disorganization and insight (Dickerson et al., 1997, Baier et al., 2000 and Smith et al., 2000). Studies examining the associations between impaired insight and depression, not one of the principal symptoms of schizophrenia, have been less consistent, with some investigators finding no significant relationships (Amador et al., 1994), while some more recent research has found a positive relationship between the degree of insight and depressive symptoms (Kim et al., 2003 and Buchy et al., 2009). Studies that have relied on neuropsychological measures have explored the relationship between that lack of insight and neurocognitive deficits, presumably secondary to the cerebral disease process in schizophrenia (Lysaker and Bell, 1994). In recent years a growing number of researchers have suggested that schizophrenia is fundamentally a disease of neuropsychological dysfunction and that previous research has over-emphasized clinical symptomotology (Gold and Harvey, 1993, Mohamed et al., 1999a, Mohamed et al., 1999b and Keefe et al., 2003). Some studies have reported a significant association between impaired insight and executive functioning (Drake and Lewis, 2003, Simon et al., 2006 and Monteiro et al., 2008), memory (Smith et al., 2000, Rossell et al., 2003 and Keshavan et al., 2004) or attention (Lysaker and Bell, 1995). Imaging studies have found dysfunction in cortical areas, which are believed to support these neurocognitive functions, and are also potentially linked with deficits in insight (Raij et al., 2012). However, other studies have failed to detect a relationship between insight and neurocognitive functioning (Cuesta et al., 1995, Collins et al., 1997, Freudenreich et al., 2004 and Goodman et al., 2005), thus undermining the view that the lack of insight in schizophrenia reflects neuropsychological impairment. The reasons for these discrepancies are not clear. They may be due to methodological differences, such as the use of different measures of insight and/or neurocognitive functioning, differences in the reliability with which the measures are used, failure to assess or control for global cognitive status or intelligence, and diagnostic and psychopathological variability between subjects in different studies (Shad et al., 2006). Another possible explanation for inconsistent results is the complexity of insight construct. Insight is a multidimensional construct that can include recognition of the presence of mental illness, understanding the consequences of the disorder, and appreciating the need for treatment. Therefore studying insight with a focus on these different dimensions may reveal a different relationship between insight and neurocognition and symptoms. It is also possible that the variability in studies of the relationship between neurocognitive measures and insight reflects a true lack of any robust relationship between the two. In order to further examine these relationships in a new cultural context, the current study aims to explore the relationship between different dimensions of insight and both clinical measures and neurocognitive functions among a single sample of patients with chronic schizophrenia hospitalized in a large psychiatric hospital in Southern China. In this study, neurocognitive functioning is measured by the Chinese translation of the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB), which has been accepted as a standard measure of cognitive functioning by the U.S. Food and Drug Administration for use in clinical trials of medications intended to improve neurocognition (Marder and Fenton, 2004).

Taken together the results of our study support the view that lack of insight in chronic schizophrenia is significantly associated with symptomatology but not with neuropsychological functioning as measured by the MCCB. Although robustly adding to data on the relationship of lack of insight to symptoms and measures of neurocognitive function in a novel context, that of Southern China, the study design did not clarify the underlying causes of the lack of insight in schizophrenia. New methods may be needed to understand the reasons for poor insight and to find ways to improve it. Improved insight remains a fundamental target for restoring functioning and quality of life in individuals with a diagnosis of schizophrenia, and should be among the primary goals of future clinical interventions.