Cognitive Rehabilitation in Schizophrenia
Cognitive Rehabilitation in Schizophrenia
Patients with schizophrenia have profound and disabling cognitive deficits. More so than positive or negative symptoms, cognitive deficits impair daily functioning and contribute most to chronic disability and unemployment.1,2
Unlike the psychotic symptoms, these deficits do not improve during periods of remission and change only minimally with antipsychotic medications.3,4
Given the enormous impact that cognitive dysfunction has on the daily lives of persons with schizophrenia, researchers and clinicians have been working for more than 2 decades on strategies to improve cognition in this population.
In this article, we summarize general concepts in cognitive rehabilitation in schizophrenia. Our goal is to provide a basic framework for clinicians who are planning to initiate a cognitive remediation (CR) program for their patients.
Cognitive deficits in schizophrenia
In persons with schizophrenia, cognitive impairments are detectable as early as age 6 or 7 years, or the earliest age at which children receive any formal psychological tests.5-8 The underlying pathology is almost certainly present in some form at birth. By first grade, children in whom schizophrenia develops are already performing at nearly a full grade equivalent below their peers.5 There appears to be a period of further cognitive decline (or rather, failure to make age-appropriate gains) between the ages of 12 and 17—several years before the first psychotic episode.5,6,9 After the first episode, and the patient has stabilized clinically, the cognitive deficits remain fairly stable.10-12 At that point, scores of global cognition range from between 1 and 2 standard deviations below those of healthy cohorts.13,14
While all domains of cognition are affected in schizophrenia, there are selective areas of increased impairment—particularly verbal and visuospatial memory, attention, executive function, and speed of processing (Table 1).15-20 Verbal memory impairments are the most robust and the most profound.10,14-16,18 Impairments in cognition are not related to illness state and are present and stable even during periods of positive-symptom remission. In fact, positive symptoms and cognitive deficits are only negligibly correlated.21 However, negative and disorganization symptoms show modest correlations with cognition.21,22
Functional consequences of cognitive deficits
Relative to the positive, negative, and disorganization symptom domains, cognition is the strongest predictor of functional outcome.1,2 Cognitive deficits in schizophrenia have been shown to interfere with various aspects of daily functioning, including employment, independent living, and quality of life.23-26 In 2 literature reviews, Green and colleagues1,2 demonstrated that 4 specific neurocognitive domains were significantly associated with functional outcomes: executive functioning, immediate verbal memory, secondary verbal memory, and vigilance. Community activity (eg, working, going to school) was predicted by measures of executive functioning and secondary verbal memory. Social problem-solving skills were associated with levels of secondary verbal memory, vigilance and, to a lesser extent, executive functioning. Psychosocial skill acquisition was most frequently linked with immediate and secondary verbal memory.2
Definition of cognitive rehabilitation
There are 2 main techniques in cognitive rehabilitation: remediation and compensatory approaches. CR is designed to stimulate new learning, or relearning, of cognitive tasks, and thus, to improve domains of deficit. Compensatory approaches seek to make improvements in the patient’s functioning by avoiding areas of impairment and recruiting other intact cognitive domains or by creating a supportive external environment.27
Cognitive impairment in schizophrenia is profound, is enduring, and significantly negatively affects functional outcome and the ability to live and work independently.
This article reviews methods to rehabilitate cognition in schizophrenia and suggests strategies for instituting a cognitive remediation (CR) program.
For clinicians interested in CR for their patients, this article describes the basic structure of such a program and gives references for relevant and useful resources.
Compensatory approaches aim not only to improve cognitive functioning by reducing errors in the learning process but also to minimize impediments to activities of daily living and to create a supportive home environment. Errorless learning (EL) and cognitive adaptation training (CAT) are 2 compensatory approaches that have yielded successful outcomes when they are used in patients with schizophrenia.
EL is guided by the theory that certain neurologically impaired groups, including persons with schizophrenia, have difficulty in learning when their mistakes are corrected in an effort to guide future behavior.28 EL aims to eliminate any errors when new tasks are being learned. This approach reduces each new task to be learned into small component parts that are then overlearned through “imitative learning and repetitive practice of perfect task execution.” By doing so, EL relies on implicit memory processes; this provides an advantage for patients whose explicit memory abilities are compromised. Implicit learning refers to learning that occurs unconsciously and that is often procedural (eg, riding a bike). In contrast, explicit learning is conscious and is often more information-based.
Compensatory strategies have also been applied to the schizophrenia patient’s home environment. CAT introduces environmental adaptations that are suited specifically to the executive impairments common among schizophrenia patients. Its aim is to reduce the cognitive burdens, functional requirements, and overall stress of everyday living in each patient’s personal space.29
During home visits, CAT therapists check for safety hazards and ensure that necessary supplies are available. The therapists may also assist in modifying and reorganizing the home in a manner customized to the individual patient’s needs. For example, in the bedroom, clothing drawers are labeled and colored bins are used for the sorting of dirty and clean clothes. In the bathroom, grooming supplies are moved to be more easily accessible and pill containers are introduced to organize medications. In addition, patients can be trained to use watches or other devices with alarms to cue themselves to take medications and complete other tasks.30
Cognitive remediation techniques
While early CR programs used paper and pencil tasks, most are now computerized. Some remediation programs use a mix of general educational software, but many train participants with specialized computer software designed to improve cognition (Table 2).31 Often the software is adapted from computer exercises for remediating age-related cognitive decline, brain injuries, or learning disabilities in children.32,33 Currently, most programs use a form of drill and practice training, which refers to the use of hundreds of trials of the same exercise to “push” intrinsic learning systems that are hypothesized to be intact in schizophrenia.34 Because of its repetitive nature, drill and practice runs the risk of boring participants. This is mitigated by the use of computer game–like motivations and rewards, such as colors, noises, increasing scores, and encouraging words.
A few CR programs focus primarily on a strategy-coaching approach, in which the therapist and a small group of patients discuss methods and strategies to improve cognition and to use cognitive-training exercises. Strategy-coaching methods do not usually focus on the repetition of hundreds of trials per exercise; rather, they place more emphasis on developing and maintaining motivation in the participants.31