Garden, Sharin E A; (2003) An investigation into the executive functioning of methadone-maintained patients. Doctoral thesis (Ph.D.), University College London (United Kingdom).

Text An_investigation_into_the_exec.pdf Download (5MB)

Abstract

Recent studies of cognitive deficits associated with substance use have converged with extant neuroimaging literature upon the notion that chronic substance users exhibit impairments on executive-type tasks mediated by orbitofrontal and ventromedial prefrontal cortex. However, few studies have examined the executive functioning of patients on daily methadone-maintenance treatment. This thesis aimed to investigate the executive abilities of 16 methadone-maintained, chronic polydrug-using, patients compared with 14 non-drug using individuals. The groups did not differ significantly on premorbid IQ. current non-verbal reasoning, gender, ethnicity and employment status. Executive abilities related to response initiation and inhibition, responsivity to reward and rule attainment were explored because impairments on these tasks have been described as being of clinical significance. Executive skills related to planning and multi-tasking behaviour were also assessed on an "ecologically-valid" Hotel task, designed to mimic the skills involved in open-ended everyday activities faced in real- world settings. Self-ratings of executive problems on a dysexecutive questionnaire were explored in relation to independent ratings by patients' keyworkers and performance on executive tasks. Methadone-maintained users performed significantly more poorly on multitasking and appeared to use less efficient strategies compared with controls. These group differences were robust to covariance of depression, age and years of education. However, the same covariates influenced findings on tasks tapping response inhibition, reward responsivity and rule attainment. There was no evidence that substance users lacked insight into their executive difficulties, moreover keyworkers rated their patients' difficulties as less severe than patients' self-ratings. The results imply that methadone-maintained patients may have more difficulty than non-drug using individuals on activities that require intact planning and organisation skills, a finding which may have implications for their ability to engage in the tasks of therapy and rehabilitation. Similarly, the results suggest that cognitive deficits may underlie many of the difficulties faced by chronic substance users' in organising and maintaining their everyday lives. Techniques utilised in neurological rehabilitation research are discussed as potentially having a useful role in reducing the impact of executive deficits on substance-users' everyday lives.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as CSVXMLJSON

Downloads by country - last 12 months

Export as JSONXMLCSV

Archive Staff Only

View Item