The Role of Cognition in Outcome in Schizophrenia and Related Disorders

Schizophrenia and related psychotic disorders can be regarded primarily as disorders of cognition, perception, and volition. Deficits in cognitive functions, including those in meta-cognition, are present in a substantial proportion of patients with these disorders and often predate the onset of psychosis.1 Neurocognition has been the subject of investigation for several decades as part of an attempt to better understand the putative underlying neurobiology of these disorders. More recently, such investigations have included its relation to course and outcome on several dimensions, including clinical and functional. In the 2 In Review articles published on this topic in this issue,2,3 the authors have provided a thorough review of the role of cognition in the context of functional outcome and, in the case of Dr Martin Lepage and colleagues,2 also included clinical outcome. In the first article, Dr Lepage and colleagues have approached the subject first from the perspective of clinical remission, especially within the context of the recent consensus definition,4 and presented evidence specifically in relation to early phase of psychotic disorders. They have concluded that there is more concrete evidence for the role of verbal memory as a marker for early remission in psychotic disorders as well as some tentative evidence in relation to social cognition. For other domains of cognition as markers of clinical remission, the evidence appears to remain equivocal or weak. In the second part of their review, they have provided evidence for the role of cognition in relation to several domains of functioning, including self-care, independent living, work, and social and interpersonal functioning. They have suggested that different domains of functional recovery may be associated with different domains of cognition. In the second article, Dr Tarek K Rajji and colleagues3 report the results of a systematic examination of longitudinal studies related to cognition and functioning across the life span and different phases of the illness, including the early as well as the later, more chronic phases. The findings from the 2 reviews are generally consistent as far as association of cognitive functioning and functional outcomes are concerned. Both reviews appear to conclude that several domains of cognition, especially verbal memory, executive function, and social cognition, are strong determinants of different domains of functioning relevant to patients’ daily lives. While both reviews have concentrated primarily on cognition, there has been an attempt to examine possible influence of other variables on functional outcome. However, this relation has been examined mostly in relation to how these other variables may influence the role of cognition in shaping functional outcome. The variables examined include, for example, the role of functional capacity, motivation, premorbid adjustment, and delay in treatment. What remains unclear is the relative and independent role of symptomatic remission and cognition, respectively, on their influence on functional outcomes, especially given the more inclusive definition of remission now applied.4,5 This may be important for several reasons. Prolonged remission of symptoms is likely to be influenced by variables that are different from those that affect cognition. For example, adherence to medication, cognitive-behavioural therapy, assertive case management, and family and other psychosocial interventions are more likely to assist in lengthening periods of remission than having any effect on cognitive functions. The latter are more likely influenced by either trait factors or variables that predate the onset of psychosis and its treatment but may be influenced by cognitive remediation, which requires a different set of skills on the part of therapists than those associated with treatment interventions outlined above. Beneficial effects of sustained remission as well as improvement in cognitive functions may both require to be combined with other ecologically sound interventions, such as supported employment, to produce any real change in patients’ lives. It remains to be seen what other variables may influence the interactional effect of interventions, such as supported employment and cognitive remediation, and (or) interventions that boost sustained remission. The 2 reviews in this issue of the journal provide further thought to making investigations of cognition in psychotic disorders relevant to improving outcomes meaningful to patients’ lives. It is hoped that future investigations will encompass all possible influences on outcomes, not limited to cognition and (or) remission of symptoms but including patients’ own strengths, such as self-esteem, social and family support, and personal resilience, as well as examine recovery outcomes that encompass patients’ perspectives.6,7

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