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Keywords:

  • cognition impairment;
  • conceptualization;
  • insight;
  • neuroanatomy;
  • schizophrenia

Abstract

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Lack of insight into illness is a prevalent and distinguishing feature of schizophrenia, which has a complex history and has been given a variety of definitions. Currently, insight is measured and treated as a multidimensional phenomenon, because it is believed to result from psychological, neuropsychological and organic factors. Thus, schizophrenia patients may display dramatic disorders including demoralization, depression and a higher risk of suicide, all of which are directly or indirectly related to a lack of insight into their illness, and make the treatment difficult. To improve the treatment of people with schizophrenia, it is thus crucial to advance research on insight into their illness. Insight is studied in a variety of ways. Studies may focus on the relationship between insight and psychopathology, may view behavioral outcomes or look discretely at the cognitive dysfunction versus anatomy level of insight. All have merit but they are dispersed across a wide body of literature and rarely are the findings integrated and synthesized in a meaningful way. The aim of this study was to synthesize findings across the large body of literature dealing with insight, to highlight its multidimensional nature, measurement, neuropsychology and social impact in schizophrenia. The extensive literature on the cognitive consequences of lack of insight and the contribution of neuroimaging techniques to elucidating neurological etiology of insight deficits, is also reviewed.

AMONG PATIENTS WITH psychiatric disorders, patients with schizophrenia more often exhibit poor insight concerning their mental disorder.1 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. That study found that 50–80% of patients lack, either partially or totally, insight into their mental disorder.2 A rich literature indicated that unawareness of illness is associated with defects in cognitive functions such as attention, memory, language, executive functioning and social cognition.3–9 Furthermore, poor insight in schizophrenia has been proposed to result in poor treatment compliance,10,11 poor social and interpersonal functioning,12,13 poor prognosis, and higher risk of relapse.14 Other studies reported that poor insight may increase the incidence of depression, hopelessness, low self-esteem15–19 and more generally poor quality of life (QOL).13,20–22 Over the past decade there has been an increase in research on the conceptualization and assessment of insight, but the relationship between insight and neurocognitive impairment, severity of psychopathology or functional recovery remains unclear.23 Understanding the mechanism of lack of insight in schizophrenia and its clinical and social implications is a major challenge for the care and treatment of people with this deleterious mental disorder. The aim of the present study was to give an up-to-date account of research and to present a coherent view on insight in schizophrenia, with particular emphasis on the concept of insight in relation to clinical aspects, psychopathology, and QOL as well as neuroscience to understand the neurobiological mechanisms underlying insight deficit in schizophrenia.

CONCEPT OF INSIGHT

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Insight is a concept that is intimately linked to mental illness, and which is nowadays recognized as an important phenomenon in psychiatric practice. It refers to a complex state of awareness of patients of their own illness, and its earliest definition in relationship to schizophrenia dates back to the 1930s, when Aubrey Lewis defined insight as ‘a correct attitude to morbid change in oneself’.24 Later, in the early 1990s, insight was suggested to consist of three dimensions: recognition that one has a mental illness; the ability to label unusual mental events as pathological; and adherence to treatment.25 More recently, several authors have characterized insight as awareness of neuropsychological defects including attention, memory, and problem solving.26–32 Insight, however, may not be viewed as a simple balance between awareness and unawareness of illness. For example, Amador et al. have stressed the distinction between awareness and attribution of psychotic symptoms, based on the observation that some patients may recognize signs of illness but attribute them to causes other than abnormalities in their mental states.1 The picture can be even more complex, because schizophrenia is not always associated with lack of insight. This observation made Cole argue for a more accurate diagnostic classification of insight that includes the following specifiers: (i) schizophrenia with preserved insight; (ii) schizophrenia with impaired insight, predominately neuropsychological features; (iii) schizophrenia with impaired insight, predominately emotional features; and (iv) schizophrenia with impaired insight, with mixed neuropsychological and emotional features.33 Cole asserted that these additional specifiers will also improve the validity of predictions regarding diagnosis and treatment response.

INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Lack of insight has initially been considered as one of the most frequent symptoms in schizophrenia,34–36 before it was taken to be as a factor that determines the other symptoms. Several studies have since examined the relationship between insight and symptoms in schizophrenia, and have demonstrated namely the existence of a negative correlation between insight and the severity of positive symptomatology.23,37–42 Nakano et al. found that negative symptoms were negatively associated with overall insight, especially with awareness of mental illness and treatment compliance,43 while Smith et al. found a small relationship between awareness of current symptoms and negative symptoms.44 This result, however, failed to be reproduced by Collins et al.45 In a meta-analysis, Mintz et al. reviewed 40 published studies and found a significant, but small, relationship between both positive and negative symptom severity and insight, with age of onset and acute versus chronic disease status serving as moderating variables, and that 3–7% of the variance in insight was explained by severity of symptomatology in schizophrenia patients.23

Adopting a large view of the relationship between insight and symptoms, several investigations have examined the link between disorganized symptoms and clinical insight, and many of them have found a significant relationship between insight and disorganized symptoms.23,46–51 Disorganization in patients with schizophrenia represents the most direct clinical expression of mental dissociation and may preclude the capacity to engage in abstract thinking needed to reflect rationally on their anomalous experiences, leaving the individual with schizophrenia without a coherent concept of normality. In a recent study, the disorganization factors of the Positive and Negative Syndrome Scale (PANSS) as proposed by Van der Gaag et al.52 emerged as the statistically significant contributors for insight in relation to the Scale to assess Unawareness of Mental Disorder (SUMD) current and past awareness of symptoms.53 There are other studies, however, that have not found such a relationship between insight and disorganized symptoms. One study found no relationship between these variables.54 One study found a significant association between disorganized symptoms and two subscales of an insight measure but did not find such an association with seven other indices of insight examined.55 In contrast, a few studies have investigated the relationship between cognitive insight and psychopathology. For example, Pedrelli et al. reported only mild correlations between positive, negative symptoms and the Self-Certainty scale of the Beck Cognitive Insight Scale (BCIS) in outpatients.56 Later, in a small sample, Warman et al. demonstrated that individuals with active delusions (n = 33) had higher Self-Certainty scores and that non-deluded patients (n = 11) had higher Self-Reflectiveness scores.57 Engh et al. investigated the same question in a cross-sectional study of 143 patients.58 They argued that the occurrence of delusions is associated with low self-Reflectiveness and high self-certainty. In contrast, Buchy et al. suggested that non-delusional participants did not differ on their Self-Certainty compared to delusional participants despite their higher Self-Reflectiveness.59 In addition to delusions, others symptoms such as hallucinations have been found to be associated with high self-Reflectiveness and low self-certainty in the absence of delusions, reflecting more open-mindedness and higher cognitive insight.58 Altogether, these data support a specific causal link between insight and disorganized symptoms. Therefore, more studies with larger samples involving follow up for longer periods will be valuable to understand the nature of the relationship between the specific dimensions of insight and clinical symptoms of schizophrenia, taking into account the stages of the disease, age of disease onset, and clinical factors such as symptom severity.

ETIOLOGY OF POOR INSIGHT

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

The etiology of lack of insight in patients with schizophrenia is not clearly known, but different explanatory models and theoretical approaches have emerged. Neuropsychology describes poor insight in schizophrenia as a result of cognitive deficits that appear as a consequence of dysfunction in neural processes,60 especially in frontal or parietal regions.40,60,61 Amador et al. underscored the similarities between lack of insight in schizophrenia and anosognosia in neurological disorders: they suggested that both conditions shared a common etiology in parietal and/or frontal lobe dysfunction.1

Little is known about the mechanisms that may underlie poor insight in schizophrenia. For instance, the association between neurocognitive deficits and poor insight was assessed.62 In addition, preliminary findings from a pilot study suggested that poor insight was more strongly related to meta-cognitive than to cognitive deficits per se (e.g. free-choice performance accuracy from the Wisconsin Card-Sorting Test [WCST], which depends on meta-cognitive skills of monitoring and control, is an important mediator between basic cognitive skills and the clinical phenomena of poor insight).63 In several studies, however, poor insight in schizophrenia was defined as denial of illness, a psychological coping mechanism.1,64–66 Psychodynamic explanations described denial of illness as a defense mechanism that protects the individual from distress. Acknowledgment and acceptance of one's own mental illness would diminish self-esteem.15,65,67 In clinical studies, lack of insight was shown to be independent from positive and negative symptoms in schizophrenia: poor insight would be a primary symptom of the disorder, intrinsic to delusions and hallucinations.45,68 Unfortunately, the weakness of the existing relationship between insight and severity of symptomatology on the one hand, and between insight and emotional state on the other hand, suggests that both psychodynamic and clinical models are not sufficient explanatory models.23,69

ASSESSMENT OF INSIGHT

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

In clinical/psychopathological and neurocognitive studies, several instruments exist for assessing insight and many of them seem to be measuring a similar construct. The Hamilton Depression Rating Scale (HDRS),70 the Present State Examination,71 the Schedule for Affective Disorders and Schizophrenia,72 and the PANSS,73 all contain one item that assesses general insight, and all have high correlations with more multiple-item insight scales, as reported by Lincoln et al.18 Low correlations between general insight and scales or subscales that address additional aspects of insight, such as insight into past disorder, or which are based on a different concept of insight, such as cognitive insight,18 prove the importance of semi-structured interview and self-report methods that have been designed to assess insight as a multidimensional characteristic (Table 1). Compared to interview techniques that require more time and inter-rater reliability to be established, self-reporting methods have several potential benefits. Marks et al. suggest that the development of a self-report questionnaire may eliminate potential researcher and clinician biases, such as the tendency to rate patients with either lower general intelligence or fewer communication skills, as having poorer insight.74 Also, self-report measures of insight may be more sensitive to associations with variables relevant to the etiology of insight than single items from general symptom rating scales.

Table 1.  Different psychometric scales for measuring insight
Type of insight scaleMeasure of insightNo. itemsFeatures of scaleStudy
Semi-structured interviewScale for Assessment of Unawareness of Mental Disorder (SUMD)37Evaluates present and past insight into mental disorder, social consequences, need for treatment, and attribution of symptom to disorderAmador & Strauss78
Scale for Assessment of Insight, Extended (SAI-E)12Assesses recognition of illness, compliance with treatment and ability to label mental events as pathologicalDavid25
Insight and Treatment Attitudes Questionnaire (ITAQ)11Evaluates perception of treatment and acceptance of illness labelMcEvoy et al.75
Measure of Insight into Cognition – Clinician Rated (MIC-CR)12Assesses both awareness and attribution of relative cognitive status in the areas of attention, executive functioning, and memory.Medalia & Thysen32
Self-reportBirchwood Insight Scale (BIS)8Measures awareness of illness, ability to re-label psychotic symptoms, and recognition of the need for treatment.Birchwood et al.79
Insight Scale (IS)32Measures individuals' degree of self-knowledge.Markova & Berrios76
Awareness of Being a Patient Scale (ABPS)25Assesses the recognition of the need for treatment and acceptance of the treatment situation.Hayashi et al.80
Subjective Experience of Negative Symptoms (SENS)24Measures awareness, causal attribution, and disruption or distress.Selten et al.81
Beck Cognitive Insight Scale (BCIS)15Measures reflectiveness, objectivity, openness to feedback and self-certaintyBeck et al.77
Self-Appraisal of Illness Questionnaire (SAIQ)17Assesses beliefs about the outcome of illness, acknowledgment of a need for psychiatric treatment, and extent of worry about illness and illness-related issues.Marks et al.74

The Insight and Treatment Attitudes Questionnaire was developed to measure two dimensions of insight: the patient's failure to acknowledge illness, and the need for treatment.75 Later, Markova and Berrios constructed the Insight Scale self-report, which incorporated additional factors, such as self-knowledge about not only how the disorder affects the patient, but also about how the disorder affects the patient's interaction with the world.76 In recent years, SUMD has been used frequently to assess insight in schizophrenia and its relationship to psychopathology. This scale that assesses current and retrospective awareness of having a mental disorder, the effects of medication, the consequences of mental illness, and the awareness and attributions for the specific signs and symptoms of the disorder, shows high correlation with the insight item on the HDRS.39 Beck and colleagues noted that patients with major psychoses typically have reduced capacity to reflect rationally on their anomalous experiences and to recognize that their conclusions are incorrect, and developed the BCIS to assess two domains: Self-Reflectiveness (captures the willingness to acknowledge fallibility, consider alternate explanations, and recognize dysfunctional reasoning) and Self-Certainty (taps overconfidence in current beliefs and judgments).77 High scores on the subscale self-reflectiveness and low scores on the subscale self-certainty is considered normal. The two subscale scores were weakly intercorrelated, indicating that they represent two different dimensions of cognitive insight.82 Weak to moderate associations have also been found between the two subscales of the BCIS, and the Birchwood measure of insight56,77 and the PANSS insight item in schizophrenia,82 indicating that cognitive and clinical insights represent different domains.

INSIGHT, COGNITION AND EMOTIONS

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

In recent years, cognitive, emotional and behavioral consequences of lack of insight in schizophrenia have been well documented. In particular, several studies have shown that patients with objective cognitive impairment exhibit poor insight concerning symptoms of schizophrenia such as hallucinations, delusions and paranoia.39,40,55,75,77,83–85 In the early stages of schizophrenia and in the first psychotic episode, cognitive dysfunctions have been demonstrated.86,87 Longitudinal studies have shown that these impairments are stable in time.88 In another study, insight ability was significantly correlated with performance in visual object learning, verbal working memory and identification of facial emotions.89 This evidence suggests that poor insight may be associated with executive functions, although the literature dealing with the relationship between insight and neurocognitive functions showed contrasting results. Indeed, while some studies reported a significant correlation between poor insight and impairment of executive functions,12,60,62,90–94 memory,44,95,96 and attention,97 others did not corroborate these findings.50,89,98 Meta-analyses show that neuropsychological dysfunction, specifically impairment of set-shifting and error monitoring, contributes to poor insight.99 In a recent study, lack of insight in schizophrenia patients was partly explained by their inability to process new information from the environment.100 Lecardeur et al., however, explored the relationships between cognitive complaints assessed on the Subjective Scale to Investigate Cognition in Schizophrenia27 and suggested that schizophrenia patients might be conscious of their cognitive deficits in spite of a lack of insight concerning their psychotic symptoms.101

INSIGHT AND META-COGNITION

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Few studies have attempted to link lack of insight to cognitive processes other than those mentioned here, namely learning, problem solving, decision-making, reasoning, and calculation abilities. By contrast, it is interesting to review studies that have addressed higher order cognition (i.e. meta-cognition). One newer model of insight that may help resolve some of these paradoxes suggests that different kinds of deficits in meta-cognition, or the ability to think about thinking, may play a unique and possibly moderating role in the development of poor insight.102 It is known that insight requires higher level cognitive processing. This includes assessment and correction of distorted beliefs and misinterpretations. How individuals assess their own judgment is perhaps central to these complex cognitive and emotional consequence features of poor insight in schizophrenia patients. To account for this capacity, also termed as belief flexibility, Beck et al. developed the concept of ‘cognitive insight’ and constructed a scale (BCIS) that allows its assessment in psychotic disorder.77 The BCIS captures two domains: (i) Self-Reflectiveness, the willingness to acknowledge fallibility, consider alternate explanations, and recognize dysfunctional reasoning; and (ii) Self-Certainty, overconfidence in current beliefs and judgments.56,57,77 Beck and Baruch showed that psychotic patients expressed, not only consistent distortions of their experiences, but also, an inability to distance themselves from these distortions, and inability to correct feedback.77 More recently, Raffard et al. showed that poor ‘basic awareness of illness’ and ‘awareness of social consequences of illness’ were associated with impaired performance on the Rule Shift Cards subtest, a measure of cognitive flexibility.100,103 Similarly, Chen et al. used the WCST to assess verbal intelligence, verbal fluency, and verbal and visual memory.104 They suggested that effects of executive dysfunction on insight impairment occurred as a possible mechanism of the relationship between reduced cognitive flexibility in set shifting and greater tendency toward relapse in first-episode schizophrenia. These findings suggest also that factors other than cognitive functions might be associated with capacity for insight in patients with schizophrenia.

INSIGHT, DEPRESSION AND SUICIDE

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Schizophrenia patients have a higher mortality rate than healthy people for different reasons, including suicide.105–108 Suicide remains a tragically common outcome, the incidence of which is negatively correlated with patient age,109 although demoralization, hopelessness and depression have been reported to lead to suicidal behavior.105,110–113 Mintz et al. reported a modest but significant correlation between depression severity and insight capacity.23 Indeed, in adolescent schizophrenia, Schwartz-Stav et al. reported that depression, hopelessness and suicidal risk were strongly correlated with insight capacity.114 Taken together, these results suggest that there is a chain of causality from insight to depression to suicide. In contrast, Staring et al. suggested the association between insight and depression, low QOL, and negative self-esteem is moderated by stigma.16 Patients with good insight accompanied by stigmatizing beliefs have the highest risk of experiencing low QOL, negative self-esteem, and depressed mood. In contrast, other studies reported no relationship between awareness of mental disorder, depression and suicide intention.18,115,116 The method used to assess insight varies across studies. It is highly possible that the method used to assess insight could influence the results and the nature of association between insight and depression and suicide intention. Thus, current knowledge on the relationship of insight to depression and suicide is inconclusive.

INSIGHT AND POOR QUALITY OF LIFE

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Contradictory results were found regarding the relationship between insight into illness and QOL in patients with schizophrenia. Some studies have found no relationship between insight and QOL in schizophrenia.11,117–120 Other studies found that good insight into having a mental illness significantly related to better social functioning and expert-rated QOL.121,122 Later, in a study of 131 patients with a psychotic disorder (103 with schizophrenia, 28 with schizoaffective disorder), Hasson-Ohayon et al. noted that greater sense of emotional wellbeing was associated with awareness into the need for treatment.20 Sim et al. also reported, in patients with first-episode schizophrenia, significant improvements in their level of awareness of the consequences of their mental illness, effects of treatment as well as psychopathology in relation to a greater subjective sense of wellbeing over time.123 Patients with acute schizophrenia, however, who had greater self- and expert-rated insight into illness, reported lower subjective QOL.124 Recently, Staring et al., using the self-report Euro-QOL, assessed five dimensions of QOL (EQ-5D) in patients with schizophrenia: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.16 The authors reported a correlation between poor insight and low QOL, especially when accompanied by stigmatizing beliefs. In contrast, Nakamae et al. found no significant association between SUMD and EQ-5D scores in patients with chronic schizophrenia.125 In another study, Hasson-Ohayon et al. assessed schizophrenia patients using the Wisconsin Client Quality of life Questionnaire-Mental developed by Becker et al.126,127 They reported that scores on six out of seven dimensions of QOL were correlated with level of general awareness of illness. It is obvious that poor insight impacts negatively on the QOL of people with schizophrenia, namely by reducing their hope.126,128 More recently, Kurtz and Tolman, using the Lack of Judgment and Insight item on the PANSS as a measure of insight into illness, and Subjective QOL (SQOL), which targets subjective satisfaction with one's living situation, work, social contacts and psychological state, confirmed that illness insight was inversely related to SQOL as reported by Aghababian et al. using the same design.129–132 Similarly, in 1432 schizophrenia patients Mohamed et al. found a small but significant correlation between higher insight and lower QOL.19 In light of these studies, and the fact that severity of depression is positively related to SQOL,129,133–135 evidence suggests that the relationship between insight and QOL might be different between acute and chronic stages of schizophrenia patients, and that psychoeducational and cognitive remediation programs may directly and positively increase their QOL and the usefulness of their insight into their illness.

FUNCTIONAL NEUROANATOMY OF INSIGHT

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES

Intuitively, one might expect that a complex mental construct such as insight would be mediated by brain regions located at a high hierarchical level. These would culminate in the prefrontal cortex, but would also involve connected regions of the parietal and temporal cortex. With the development of brain imaging techniques, a number of recent studies have examined the cerebral correlates of poor insight in schizophrenia, and their results are beginning to provide answers to this important question. Interestingly, several studies based on cognitive test data have related lack of insight in schizophrenia to deficits in frontal cortical systems.12,40,44,60,62,74,94,95,136,137 At a macroscopic level, some studies have used magnetic resonance imaging, voxel-based morphometry, computed tomography and diffusion tensor imaging to examine the relationship between total brain volume as well as some cortical structures implicated in higher mental functions, and insight capacity. Table 2 summarizes a number of structural neuroimaging studies of insight. Some studies have reported an association between poor insight and reduced total brain volume,138,139 ventricular enlargement,140 frontal lobe atrophy,141 reduced frontal lobe volume,142–144 and gray matter deficits in the cingulate gyrus,144–146 temporal lobe,144,147,148 parietal lobe,147,148 precuneus,146–148 and the right posterior insula.149 Other studies, however, have not found any significant correlations between lack of insight and total brain volume, total ventricular volume and gray or white matter volumes in the prefrontal region.14,50,150 This inconsistency could arise from the complex nature of insight and the use of a variety of insight assessments.

Table 2.  Studies investigating brain anatomical abnormalities and insight
StudyParticipants (n)Neuroimaging and insight measuresResults
  • Insight is assessed using a single sub-item with scores ranging from 0 to 4, with higher scores suggesting more severe lack of insight.

  • BIS, Birchwood Insight Scale; CT, computed tomography; DLPFC, dorsolateral prefrontal cortex; DTI, diffusion tensor imaging; HDRS, Hamilton Depression Rating Scale; ITAQ, Insight and Treatment Attitudes Questionnaire; LPC, left posterior cingulate cortex; LPG, lateral parietal gyri; LSMTG, left superior-middle temporal gyrus; MFG, middle frontal gyrus; MRI, magnetic resonance imaging; OFC, orbitofrontal cortex; PANSS, Positive and Negative Syndrome Scale; RAC, right anterior cingulate cortex; RITG, right inferior temporal gyrus; RSTG, right superior temporal gyrus; SAI-E, Expanded Schedule of Assessment of Insight; SUMD, Scale to assess Unawareness of Mental Disorder; VBM, voxel-based morphometry.

Antonius et al.14826 patients with schizophrenia and schizoaffective disorderDTISymptom unawareness was linked to white matter abnormalities in various frontotemporal brain regions. Misattribution of symptoms was related to deficits in the white matter in parietal and temporal brain regions.
SUMD
Buchy et al.15179 inpatients and outpatients with a first-episode psychosis mixedVBMRegional thickness in frontal cortex is associated with awareness of illness in the early phase of psychosis. Prominent thickness reductions in parietal and temporal cortices associated with awareness of illness and awareness of treatment need and efficacy.
SUMD
Palaniyappan et al.14957 stable patientsMRIWhite matter volume of the right posterior insula, but not the left, was related to reduced insight.
Insight assessed using a single sub-item
Morgan et al.14682 individuals with first-onset psychosisMRISignificant correlation between no symptom re-labeling and global and regional gray matter deficits primarily located at the posterior cingulate gyrus and right precuneus/cuneus.
91 healthy controlsSAI-E
Cooke et al.14752 outpatients with chronic schizophrenia and schizoaffective disorderVBMSignificant correlations between: higher awareness of problems and increased regional gray matter volume in the left precuneus; higher symptom re-labeling and greater absolute gray matter in the RSTG; and, better awareness of illness and attribution to illness and greater regional gray matter in the LSMTG, the RITG, and the LPG.
30 healthy controlsSAI–E/BIS
Sapara et al.14428 chronic patientsMRISignificant correlation between insight and cortical atrophy in IFG and SFG.
20 healthy controlsBIS/SAI-E
Bassitt et al.15050 outpatientsVBMNo significant inverse correlations between the degree of insight impairment and total brain volumes.
30 healthy controlsSUMD
McEvoy et al.139226 first-episode schizophreniaMRILarger brain volumes associated with more insight
ITAQ
Lee et al.15214 patientsMRIIncrease in left medial prefrontal cortex activity was specifically associated with improved insight
14 healthy controlsSchedule of Assessment of Insight
Shad et al.14314 first-episode schizophreniaMRIInsight deficits were associated with DLPFC/OFC.
SUMD
Shad et al.15335 first-episode schizophreniaMRIInverse correlation between insight and right DLPFC volumes
Insight item of HDRS
Ha et al.14535 paranoid schizophreniaVBMA positive correlation between better insight, and gray matter concentrations in the LPC/RAC as well as the bilateral inferior temporal regions.
35 healthy controlsInsight-item (G12) from PANSS
Rossell et al.5078 chronic male patientsMRINo significant correlations between whole brain, white and gray matter volume and degree of insight.
36 normal maleSAI-E
Flashman et al.14215 patients with schizophrenia and schizoaffective disorderMRISignificant correlation between deficits in DLPFC/OFC/MFG and poor insight
SUMD
Flashman et al.13830 patients with schizophrenia spectrumMRIReduced whole brain volume associated with poor insight
SUMD
Larøoi et al.14121 patientsCTFrontal lobe atrophy was associated with poor insight
21 healthy controlsSUMD
David et al.14150 inpatients mixedCTNo significant correlations between lack of insight and total ventricular volume and frontal lobe function
PANSS
Takai et al.14022 chronic schizophreniaMRIVentricular enlargement associated with poor insight
G12 item of the PANSS

These neuroimaging approaches support a neurological etiology of insight deficits in schizophrenia and suggest that the multidimensional construct of insight has multiple neural determinants. These results point to the possibility that other brain regions including the temporal and parietal lobes might also be important in determining insight levels in schizophrenia. Clearly, more research is needed on the cerebral anatomical/functional correlates in order to develop a functional anatomy of insight and its defects in schizophrenia.

Conclusions

In summary, because of a multitude of conceptualizations of insight, of theories of its etiology and measures, insight appears as a multidimensional and complex phenomenon. Poor insight in schizophrenia, rather than being a simple primary symptom of the disease, has major consequences on cognitive and meta-cognitive processes (such as beliefs), as well as on emotional state. It may also increase the incidence of depression and suicidal behavior. The psychopathological assessment of insight is marked by several paradoxes. It is thus important to develop tools to accurately assess the lack of insight in people with schizophrenia. Unfortunately, because of its complexity, measuring insight still requires the development of specific laboratory tests and sophisticated tasks derived from cognitive psychology, taking into account all dimensions of insight. Future research should focus in detail on the role of meta-cognitive processes, and examine separate components of the insight construct to explore relationships between insight into clinical symptoms and insight into cognitive impairment. Although the consequences of acknowledging one's disorder may increase feelings of hopelessness or depression for many patients, increasing the hope may have a positive impact on QOL and the usefulness of their insight into their illness. We do not know enough about the neuroanatomical and functional basis of insight, but the specific areas of the prefrontal cortex (i.e. dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate) may support poor insight in schizophrenia. The progress from neuroscience research on the neuronal correlates of insight may prove to be useful in advancing its understanding. From this perspective, the functional neuroanatomy of insight in schizophrenia (i.e. the details of structural and functional connectivity in relation to different dimensions of insight) is beginning to yield important data. The available data as at the time of writing suggest the involvement of several frontal, parietal and temporal regions. It is likely that insight, which requires high-level information processing, results from functional interactions between these cortical regions, which are known to be connected.154,155

Finally, it appears essential to better define the phenomenology of insight impairments in schizophrenia to integrate neurobiological and psychological findings as well as the social context as manifested in a number of studies discussed in the present review.

REFERENCES

  1. Top of page
  2. Abstract
  3. CONCEPT OF INSIGHT
  4. INSIGHT AND SYMPTOMS OF SCHIZOPHRENIA
  5. ETIOLOGY OF POOR INSIGHT
  6. ASSESSMENT OF INSIGHT
  7. INSIGHT, COGNITION AND EMOTIONS
  8. INSIGHT AND META-COGNITION
  9. INSIGHT, DEPRESSION AND SUICIDE
  10. INSIGHT AND POOR QUALITY OF LIFE
  11. FUNCTIONAL NEUROANATOMY OF INSIGHT
  12. ACKNOWLEDGMENTS
  13. REFERENCES