Abstract
Background
Mood disorders are serious mental health conditions that confer significant disability. Cognitive impairment is evident in a substantial proportion of individuals with mood disorders, and relates to problems in psychosocial and occupational functioning, and possibly risk of relapse. As such, cognitive function has been identified as a key target for intervention. Cognitive remediation (CR) is an intervention designed to improve cognitive function, with the overall aim of promoting functional recovery. Whilst there is some evidence that CR may engender pro-cognitive effects in those with mood disorders, few studies have examined long-term cognitive, clinical, and functional outcomes. Moreover, no study has examined the feasibility of combining CR with traditional psychotherapies in this population, despite the well substantiated finding in schizophrenia that combining the two can benefit wider functioning.
Objectives
The main objectives of this thesis are:
• to characterise the profile of cognitive impairment in the mood disorder sample at baseline,
• to examine whether the addition of CR to a long-term psychotherapy (Interpersonal Social Rhythm Therapy [IPSRT]) leads to greater changes in cognitive function, mood and psychosocial functioning compared with IPSRT alone, and
• to examine potential baseline predictors of response to IPSRT and CR, including aspects of cognitive function.
Methods
This thesis focuses on individuals across the mood disorder spectrum who were part of a parallel, randomised controlled trial comparing the efficacy of IPSRT and CR (IPSRT-CR) with IPSRT alone on cognition. Fifty-eight patients completed objective and subjective measures of cognitive function at baseline and treatment-end (12-months), along with measures of mood and functioning. Forty-eight healthy control participants also completed cognitive testing. Treatment groups were compared on multiple outcome measures, and predictors of treatment outcome were also examined.
Results
Key results were:
• Approximately 30% of the mood disorder sample had ‘clinically meaningful’ cognitive impairment at baseline when compared with the healthy control group.
• The IPSRT-CR group did not demonstrate greater improvement in cognitive function than the IPSRT group at treatment-end.
• The IPSRT group demonstrated greater improvement in psychosocial functioning than the IPSRT-CR group.
• Poorer baseline performance on measures of attention/executive function and psychomotor speed were associated with less change in mood symptom-burden following IPSRT and CR.
• Greater baseline depression severity was associated with less change in global cognition at treatment-end.
Conclusions
Contrary to study hypotheses, the addition of CR to IPSRT did not lead to improvements in cognitive function and in fact, it seemingly reduced the effectiveness of IPSRT at improving psychosocial functioning. It is likely that this was related, in part, to the acuity of the sample, with predictor analyses revealing that greater baseline depression severity was associated with less change in global cognition. Predictor analyses also showed that poorer baseline performance on measures of attention/executive function and psychomotor speed was associated with less change in mood symptom burden over the course of treatment. Thus, whilst the addition of CR did not improve treatment outcomes, it appears that targeting cognitive function continues to be a worthwhile pursuit.