Memory and attention performance in psychiatric patients: lack of correspondence between clinician-rated and patient-rated functioning with neuropsychological test results

Should cognitive impairment be included in the diagnostic criteria for schizophrenia?

Neurocognitive impairment is considered a core component of schizophrenia, and is increasingly under investigation as a potential treatment target. On average, cognitive impairment is severe to moderately severe compared to healthy controls, and almost all patients with schizophrenia demonstrate cognitive decrements compared to their expected level if they had not developed the illness. Compared to patients with affective disorders, cognitive impairment in schizophrenia appears earlier, is more severe, and is more independent of clinical symptoms. Although the DSM-IV-TR and ICD-10 descriptions of schizophrenia include several references to cognitive impairment, neither the diagnostic criteria nor the subtypology of schizophrenia include a requirement of cognitive impairment. This paper forwards for consideration a proposal that the diagnostic criteria include a specific criterion of "a level of cognitive functioning suggesting a consistent severe impairment and/or a significant decline from premorbid levels considering the patient's educational, familial, and socioeconomic background". The inclusion of this criterion may increase the "point of rarity" with affective psychoses and may increase clinicians' awareness of cognitive impairment, potentially leading to more accurate prognosis, better treatment outcomes, and a clearer diagnostic signal for genetic and biological studies. Future research will need to address the validity of these possibilities. The reliable determination of cognitive impairment as part of a standard diagnostic evaluation will present challenges to diagnosticians with limited resources or insufficient expertise. Cognitive assessment methods for clinicians, including brief assessments and interview-based assessments, are discussed. Given the current emphasis on the development of cognitive treatments, the evaluation of cognition in schizophrenia is an essential component of mental health education.

Neuropsychology and clinical neuroscience of persistent post-concussive syndrome

On the mild end of the acquired brain injury spectrum, the terms concussion and mild traumatic brain injury (mTBI) have been used interchangeably, where persistent post-concussive syndrome (PPCS) has been a label given when symptoms persist for more than three months post-concussion. Whereas a brief history of concussion research is overviewed, the focus of this review is on the current status of PPCS as a clinical entity from the perspective of recent advances in the biomechanical modeling of concussion in human and animal studies, particularly directed at a better understanding of the neuropathology associated with concussion. These studies implicate common regions of injury, including the upper brainstem, base of the frontal lobe, hypothalamic-pituitary axis, medial temporal lobe, fornix, and corpus callosum. Limitations of current neuropsychological techniques for the clinical assessment of memory and executive function are explored and recommendations for improved research designs offered, that may enhance the study of long-term neuropsychological sequelae of concussion.

Stimulating the development of drug treatments to improve cognition in schizophrenia

Cognitive impairment in schizophrenia is a core feature of the illness (i.e., not a result of clinical symptoms or drug treatments) that is related to the daily functioning of patients. Because schizophrenia is associated with poor community functioning, there is considerable interest in finding treatments to improve cognition in schizophrenia in the hopes that such improvement will yield functional benefits. Before the U.S. Food and Drug Administration could consider granting approval to any new drug for improving cognition in schizophrenia, it was first necessary to achieve consensus on the measurements and methods that would be used in clinical trials, as well as neuropharmacological targets. The U.S. National Institute of Mental Health launched an initiative to help address these obstacles to drug approval (MATRICS). This initiative has generated several additional follow-up initiatives including a clinical trial network and consensus projects for other clinical targets, such as negative symptoms. This review describes how an area that was primarily of academic interest (cognition in schizophrenia) became a focus of public health concerns and drug-development policy.

How should DSM-V criteria for schizophrenia include cognitive impairment?

Neurocognitive impairment is considered a core component of schizophrenia and is increasingly under investigation as a potential treatment target. On average, cognitive impairment is severe to moderately severe compared with healthy controls, and almost all patients with schizophrenia demonstrate cognitive decrements compared with their expected level if they had not developed the illness. Compared with patients with affective disorders, cognitive impairment in schizophrenia appears earlier, is more severe, and tends to be more independent of clinical symptoms. While the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, description of schizophrenia includes several references to cognitive impairment, neither the diagnostic criteria nor the subtypology of schizophrenia include a requirement of cognitive impairment. We forward for consideration a proposal that the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria include a specific criterion of "a level of cognitive functioning suggesting a consistent severe impairment and/or a significant decline from premorbid levels considering the patient's educational, familial, and socioeconomic background." The inclusion of this criterion may increase the "point of rarity" with affective psychoses and may increase clinicians' awareness of cognitive impairment, potentially leading to more accurate prognosis and better treatment outcomes. Future research will need to address the validity of these possibilities. The reliable determination of cognitive impairment as part of a standard diagnostic evaluation may present challenges to diagnosticians with limited resources or insufficient expertise. Various cognitive assessment methods for clinicians, including brief assessments and interview-based assessments, are discussed. Given the current emphasis on the development of cognitive treatments, the evaluation of cognition in schizophrenia is an essential component of mental health education.

Clinicians' concepts of the cognitive deficits of schizophrenia

Several compounds to improve cognition in schizophrenia are being studied in clinical trials, but little is known about how clinicians conceptualize the cognitive deficits of schizophrenia. In a pilot study, the author asked 40 psychiatrists 3 brief questions about the clinical presentation of cognitive deficits. Descriptions of cognitive deficits show high variability. Informants describe phenomenology like follow-through, attention, and emptiness as indicative of cognitive impairment. Informants' concepts of cognitive deficits overlap substantially with positive, negative, and thought disorder symptoms. Clinicians' concepts are complex and contextualized, in contrast to the discrete skills measured by neuropsychological tests. Results suggest that appropriate prescribing of cognition-enhancing medications may be challenging.

Severity of subjective cognitive impairment in patients with obsessive-compulsive disorder and depression

Previous research on obsessive-compulsive disorder (OCD) has consistently found cognitive impairments in the domains of executive and nonverbal (memory) functioning, particularly in patients with comorbid depressive symptoms. In contrast, little is known about the degree to which such deficits are cognizant to patients or the degree to which these impairments interfere with daily activities. The aim of the present study was to assess prevalence and specificity of subjective cognitive dysfunction in OCD patients. A self-rating scale, the Subjective Neurocognition Inventory (SNI), was administered to 67 OCD patients upon admission to hospital. Forty healthy and 30 depressed participants served as controls. Relative to healthy participants, OCD patients reported greater impairment on SNI subscales measuring psychomotor speed, selective and divided attention. Impairments in the OCD group were particularly pronounced in patients with severe OCD or depressive psychopathology. OCD patients were no more disturbed than depressed participants on any of the domains tested. Memory problems were only reported by a minority of OCD patients-even in patients with checking compulsions. In conjunction with prior studies showing few memory difficulties in non-depressed OCD patients, present findings further challenge the memory deficit hypothesis which claims that checking compulsions are a dysfunctional compensation for real or imagined forgetfulness.

Everyday memory functioning in obsessive- compulsive disorder

Memory performance in obsessive-compulsive disorder (OCD) is discussed as a pathogenetic risk factor for the emergence of OCD, particularly checking compulsions. At present, however, findings are mixed and little is known about memory performance in tasks relevant to everyday functioning in patients with OCD. For the present study, memory performance was assessed in 31 patients diagnosed with OCD and 33 healthy controls with the Rivermead Behavioural Memory Test (RBMT), which covers a wide range of verbal and nonverbal memory components as well as prospective memory. OCD patients performed comparably to healthy controls on the memory task for verbal, nonverbal, and prospective memory (p > .1). According to norm values, memory performance was unimpaired in most OCD patients. The present findings further challenge a broad account of the "memory deficit" hypothesis of OCD and compulsive checking, respectively.

Metacognitive control over false memories: a key determinant of delusional thinking

This article reviews the current literature on false memories in schizophrenia. Increasing evidence suggests that neither memory impairment in general nor false memories in particular can reliably differentiate patients with schizophrenia or delusions from psychiatric controls. In contrast, it is proposed that a reduced metacognitive awareness of one's own fallibility, and overconfidence in errors, may predispose a person to fixed, false beliefs (ie, delusions). Congruent with this position, a number of recent investigations suggest that the memory of patients with schizophrenia, as well as healthy subjects scoring high on delusional ideation, is corrupted by an increased number of incorrect memories held with high confidence, possibly relating to a jumping-to-conclusions or liberal acceptance bias in schizophrenia spectrum disorders. A new training approach is described that is intended to sharpen patients' awareness of such errors and reduce confidence in fallible memories. Some empirical gaps and directions for further research are outlined.

Investigation of metamemory dysfunctions in first-episode schizophrenia

A number of recent studies have suggested that schizophrenia patients share metamemory deficits, particularly, a decreased ability to distinguish between errors and correct responses in terms of response confidence (i.e., decreased confidence gap): patients are over-confident in errors while at the same time being under-confident in responses that are in fact correct. This, along with increased error rates, leads to an inflation of inaccurate but confidently held memories, which has been termed knowledge corruption. Previous studies on metamemory in schizophrenia patients predominantly tested chronic patients, leaving open the possibility that metamemory deficits stem partly from increased chronicity and long-term treatment. The primary aim of the current study was to establish whether a decreased confidence gap is also detectable in first-episode schizophrenia. For this purpose, a source memory task was administered to 30 first-episode patients with a diagnosis of schizophrenia or schizophreniform disorder, and 15 healthy control subjects. During encoding, items were read aloud by the experimenter and the participant in alternating order. For the recognition phase, participants were required to state the source of the item, and their confidence in their response. In agreement with previous studies, the patients displayed a decreased confidence gap, and increased knowledge corruption relative to controls. A reduced distinction between correct and incorrect information in metacognition is proposed to be a vulnerability factor for the development of delusions in schizophrenia.

The contribution of metamemory deficits to schizophrenia

A number of recent studies have demonstrated that individuals with schizophrenia display knowledge corruption; that is, they hold false information with strong conviction. This aberration in metamemory is thought to stem from poor memory accuracy in conjunction with impaired discrimination of correct and incorrect judgments in terms of confidence. Thirty-one participants with schizophrenia, along with 61 healthy control participants and 48 control participants with other psychiatric conditions, participated in a computerized source memory task. Whereas no differences in memory accuracy were observed between the group with schizophrenia and the group with other psychiatric diagnoses, knowledge corruption was specifically impaired in those with schizophrenia. Schizophrenia participants showed a significantly decreased confidence gap: They were more confident in errors and less confident in correct responses relative to those in the control groups. Knowledge corruption is theorized to be a potential risk factor for the emergence of delusions.

Neurocognitive impairment does not predict treatment outcome in obsessive-compulsive disorder

There is conflicting evidence pertaining to whether or not neurocognitive task performance at baseline predicts treatment response in obsessive-compulsive disorder (OCD). In the present study, we administered a set of executive neurocognitive tests with a putative sensitivity for treatment outcome to a sample of 138 OCD patients. Additionally, subjective neurocognitive dysfunction was determined via a questionnaire. All patients participated in a cognitive-behavioural treatment program (CBT). Results showed that responders (n = 73) did not differ from non-responders (n = 65) on any of the parameters except for decreased performance on the delayed alternation test (p < .1, effect size: .61). A subsidiary analysis revealed that slowing on the Trail-Making Test A and an enhanced rate of perserveration errors on the Wisconsin Card Sorting Test predicted poor outcome for the treatment of compulsions. It is concluded that neurocognitive impairment does not represent a reliable early warning sign for non-response to CBT.

A collaborative approach to targeted treatment development for schizophrenia: a qualitative evaluation of the NIMH-MATRICS project

INTRODUCTION

In 2002, the National Institute of Mental Health (NIMH) initiated a multistakeholder research process designed to stimulate the development and evaluation of medications targeting the cognitive deficits associated with schizophrenia. The first phase, Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS), sought consensus on laboratory measures for cognition, clinical trial outcome measures, and drug registration requirements. MATRICS constitutes a unique drug development model because it targeted a specific endophenotype of schizophrenia and because it engaged academic, industry, and government stakeholders in a consensus-oriented process. This study offers a preliminary qualitative evaluation of the NIMH-MATRICS project.

METHOD

Interview data are used to describe how MATRICS participants regard 3 aspects of the development of cognitive medications: the definition of the treatment target, stakeholders' role in the early development process, and anticipated dissemination complexities.

RESULTS

MATRICS participants describe the treatment target in highly varied ways and envision a wide range of public health benefits. MATRICS is perceived as inclusive, despite minimal representation from some end users. According to informants, clinical detection, documentation, and monitoring of cognition and functioning may prove problematic. More thoroughly than non-industry-employed informants, industry-employed MATRICS participants articulate strategies by which treatments can be integrated into clinical practice.

DISCUSSION

The MATRICS process did not produce a clinical concept of cognitive impairment in schizophrenia, and significant challenges remain to be addressed regarding the rational clinical use of novel pharmaceuticals for cognition. Broader inclusion of end users in translational science projects may streamline implementation and facilitate improvements in real-world outcomes.