Psychiatric disorders, such as schizophrenia, bipolar disorder, and major depression, have a devastating impact on a patient’s life and contribute great economic burden through staggering medical costs. In addition to the direct economic costs of health care, these disorders are associated with even greater indirect costs due to poor psychosocial functioning (e.g., loss of productivity, unemployment, need for caregivers). Cognitive impairments, such as problems with attention and memory, are a prominent feature of these disorders and key determinants of functional outcomes in people with severe mental illnesses (SMI), underscoring the importance of treatments targeting cognitive impairments in SMI to improve functioning.
In our recent study titled “Neuropsychological predictors of performance-based measures of functional capacity and social skills in individuals with severe mental illness,” published in the Journal of Psychiatric Research, we identified individual cognitive abilities that may serve as targets of interventions aimed at improving psychosocial functioning in people with SMI.
A transdiagnostic consideration of cognitive impairment
Much of the research informing treatments to target functionally-linked cognitive problems has been designed with the prevailing understanding of schizophrenia, bipolar disorder, and major depression as distinct diagnostic entities. Recent developments, however, are bringing about a shift within the field through findings highlighting shared influences on cognitive impairment across disorders. Although an extensive body of research has demonstrated cognitive impairments to be associated with deficits in daily living skills and social abilities within each population, no study to date has examined whether cognitive abilities predict functional and social skills across these disorders simultaneously.
Given the transdiagnostic presentation of cognitive impairments, and associated deficits in psychosocial functioning, understanding the differential relationship of individual cognitive abilities with functional capacity and social skills can lead to targeted cognitive remediation within people with SMI. As such, we investigated the strongest neuropsychological predictors of performance-based functional capacity and social skills performance across the spectrum of SMI.
We examined performance-based functional capacity in financial management and communication domains and social skills relevant to neutral and adversarial situations in 151 people with SMI (38% major depression, 25% bipolar disorder, 37% schizophrenia). We also measured psychiatric symptom severity and cognitive performance on tests of processing speed, sustained attention, working memory, verbal and visual learning, executive functioning (i.e., planning, problem-solving), and prospective memory (remembering to perform a planned action in the future).
Neuropsychological targets for intervention across diagnostic categories
We found better neuropsychological performance to be associated with better overall functional capacity and social skills. More specifically, better performance in the neuropsychological domains of working memory, sustained attention, processing speed, and executive functioning uniquely predicted better functional capacity, along with a mood disorder (vs. schizophrenia-spectrum) diagnosis. Because neuropsychological course is considered a key, independent determinant of functional outcomes across major psychiatric conditions, the emergence of diagnosis as significant predictor is consistent with findings demonstrating that shared cognitive impairments are generally less severe in mood disorders as compared to schizophrenia. Nevertheless, our results suggest that the varied cognitive impairments in people with SMI provide unique information toward predicting functional ability.
For social skills performance, less severe negative symptoms (e.g., flattened affect, amotivation) emerged as the strongest predictor of better social skills. Additionally, better executive functioning and sustained attention performance uniquely predicted better social skills, independent of diagnosis. These findings suggest that neuropsychological rehabilitation targeting these cognitive domains may improve social skills and, by extension, long-term functional outcomes in people with SMI.
It is important to note that, unlike for functional capacity, diagnosis did not emerge as an important predictor of social skill performance; although negative symptoms did. Much like cognitive impairments, negative symptoms cut across diagnostic categories, underscoring the importance of examining clinical symptoms independently of diagnostic categories.
Clinical implications and future research
The varied cognitive deficits common to schizophrenia, bipolar disorder, and major depression contribute to impairments in daily functioning and social skills in people with SMI. The current study holds important clinical implications in its use of a transdiagnostic approach: the findings offer neuropsychological targets for intervention across diagnostic categories, providing an attractive alternative to diagnosis-specific treatments that stretch limited resources in medical centers and outpatient facilities. Our results suggest prioritization of cognitive deficits within working memory, processing speed, sustained attention, and executive functioning domains in the evaluation and treatment of people with SMI. It would be interesting to follow-up on these findings and determine whether improvements in these cognitive domains contribute to change in functional outcomes. This work also sets the stage for examining the predictive utility of neuropsychological functioning and psychiatric symptom severity in explaining real-world psychosocial functioning, such as work and educational outcomes.
These findings are described in the article entitled Neuropsychological predictors of performance-based measures of functional capacity and social skills in individuals with severe mental illness, recently published in the Journal of Psychiatric Research. This work was conducted by team including Zanjbeel Mahmood and Elizabeth W. Twamley from San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology and the University of California San Diego, Department of Psychiatry and VA San Diego Healthcare System.