عوامل موثر بر خود ارزیابی شناخت و عملکرد در اسکیزوفرنی: پیامدها برای مطالعات درمانی

Awareness of illness is a major factor in schizophrenia and extends into unawareness of cognitive and functional deficits. This unawareness of functional limitations has been shown to be influenced by several different predictive factors, including greater impairment and less severe depression. As treatment efforts are aimed at reducing cognitive deficits, discovery of the most efficient assessment strategies for detection of cognitive and functional changes is critical. In this study, we collected systematic assessments from high contact clinicians focusing on their impressions of the cognitive deficits and everyday functioning in a sample of 169 community dwelling patients with schizophrenia. The patients provided self-report on those same rating scales, as well as self-reporting their depression and performing an assessment of cognitive performance and functional skills. There was essentially no correlation between patients׳ self-reports of their cognitive performance and functional skills and either clinician ratings of these skills or the results of the performance-based assessments. In contrast, clinician reports of cognitive impairments and everyday functioning were correlated with objective performance data. Depression on the part of patients was associated with ratings of functioning that were both more impaired and more congruent with clinician impressions, while overall patients reported less impairment than clinicians. These results underscore the limitations of self-reported cognitive functioning even with structured rating scales. Concurrently, clinicians provided ratings of cognitive performance that were related to scores on objective tests, even though they were unaware of the results of those assessments.

Cognitive impairment in schizophrenia has become an area of interest in research due to its impact on patients׳ everyday functioning and subsequent perpetuation of disability. Deficits in social (Wiersma et al., 2000), residential (Auslander et al., 2001) and occupational (Ho et al., 1997) domains are observed in patients with schizophrenia despite successful treatment of the active phase of the illness. Cognitive impairments are one of several factors known to predict impaired everyday outcomes. Current pharmacologic treatments have a positive effect on psychotic symptoms but a limited effect on cognition. Therefore, it is a major priority to develop treatment alternatives for cognitive deficits in schizophrenia. The assessment of cognitive impairment has been accomplished with performance-based neuropsychological (NP) tests and functional capacity (FC) measures (Harvey et al., 2007). Due to their potential to predict real-world functioning, both tools have been accepted for use in treatment studies and will be used for registration studies (Green et al., 2011). For the approval of a cognitive-enhancing drug for schizophrenia, the Food and Drug Administration (FDA) is promoting the development of a variety of methods for assessing treatment related outcomes in cognition. As a result, interview-based measures have been developed to measure cognitive functioning and cognitive changes with treatment. The Cognitive Assessment Interview (CAI) is a 10-item instrument that assess 6 of the 7 MATRICS cognitive domains, it can be completed by a patient, informant and rater, it has been recently validated and produces reliable ratings of cognitive functioning that were correlated with functional outcome (Ventura et al., 2013). The Schizophrenia Cognition Rating Scale (SCoRS; Keefe et al., 2006) is a similar 20-question interview with both the patient and an informant and has been successfully used to measure cognition outcomes after treatment with atypical antipsychotics (Harvey et al., 2011). However, there are some intrinsic limitations with interview-based assessments, including both self-reports and caregiver assessments. First, patients can be poor informants because the role played by insight in cognition has not been well examined in interview-based assessments and is likely that interview-based methods require considerable patient insight (Medalia and Thysen, 2010). Second, remotely delivered interventions may lead to patients not being seen in person, particularly in purely clinical scenarios. Third, very little is known about what influence caregiver characteristics have on their reports about the cognitive functioning of the patient (Sabbag et al., 2011), although there are clear variations in the validity of those reports. Last, it may be also be difficult to see non-clinician informants in person and therefore it will be difficult to evaluate their own cognitive abilities and emotional states. Some of these difficulties can be surmounted if high-contact clinicians generate the ratings, as there is considerable evidence that their ratings have considerably more validity than those of other informants (Bowie et al., 2007, Sabbag et al., 2011 and Sabbag et al., 2012), including both the patient and non-caregiver friend or relative informants. Lack of insight is a core feature of schizophrenia and studies have also shown that patients are unaware of their cognitive deficits (Medalia and Thysen, 2010). Previous studies demonstrated that self-reports of cognition are not well correlated with performance-based assessments (Keefe et al., 2006 and Green et al., 2011). Similar problems may exist when patients are asked to report their own levels of everyday functioning (Bowie et al., 2007, Patterson et al., 1997 and McKibbin et al., 2004). On the other hand, a recent study (Sabbag et al, 2011) has indicated that clinician ratings of the severity of real-world impairment were more strongly correlated with the results of performance-based assessments than impairment ratings generated by friends, relatives, other caregivers or patients themselves. Further, interview based assessments considering all possible informants, with a final judgment rendered by the interviewer, have been shown to be suitably correlated with the results of performance-based assessments (Keefe et al., 2006 and Ventura et al., 2013) and to be sensitive to the effects of potentially cognitively enhancing agents (Harvey et al., 2011). It is still tempting to consider the use of self-reports in clinical trials, as there is some evidence that many people with schizophrenia may have trouble identifying potential informants (Patterson et al., 1996). In addition, it may be logistically challenging for the same interviewer to collect data from patients and informants. Since clinician informants seem to generate valid reports (Bowie et al., 2007 and Sabbag et al., 2011), even without training, it is possible that collection of questionnaire data from these clinician informants would be suitable to use as outcome measures. As a result, it would be important to understand the convergence between clinician informant ratings of cognitive performance and performance-based assessments of patients, as well as understanding the relationship between real-world outcomes and these informant reports of cognitive functioning. We present a systematic study of the validity of self-reported vs clinician reported cognitive performance. All clinicians provided mailed-in questionnaire responses, with no in-person assessments performed. These clinicians received no training in completion of the questionnaires. Clinicians were asked to rate patient׳s cognitive performance and everyday functioning using the Cognitive Assessment Interview (CAI, Ventura et al., 2013) and the Specific Levels of Function (SLOF; Schneider and Struening, 1983) respectively. Patients were seen in person and reported their cognitive functioning with a structured interview focusing on the same forms completed by mail by clinicians (CAI) and completed the SLOF as a questionnaire. Patients were also assessed with performance based-assessments of functional capacity using the UCSD Performance-based Skills Assessment, brief version (UPSA-B; Mausbach et al., 2007) and neurocognition utilizing a modified version of the MATRICS Consensus Cognitive Battery (MCCB; Neuchterlein et al., 2008).