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Title: A study of improving cognitive deficits in schizophrenia using transcranial direct current stimulation with adjunct cognitive training
Author: Nalesnik, Natasza Dominika
ISNI:       0000 0004 6062 0199
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2014
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Background: Schizophrenia exerts an enormous personal, societal and financial cost and is one of the most disabling of illnesses. Even with optimal treatment, individuals with schizophrenia are commonly left with cognitive impairments impacting on key functions such as memory, attention and learning. These functions are recognised to be primarily associated with the prefrontal cortex of the brain, and modulating activity in this brain region forms the basis of different interventional approaches. This thesis examined if combining two interventions, transcranial direct current stimulation (tDCS) and cognitive training (utilising both working memory and implicit learning tasks), would synergistically improve cognitive deficits in individuals with schizophrenia. Furthermore, neurophysiological effects tDCS during working memory were investigated. Methods: This is a single blind, sham-controlled pilot study of 49 individuals with schizophrenia, randomised into real or sham tDCS stimulation groups. They participated in 4 days of cognitive training spread over a period of 6 weeks and underwent functional magnetic resonance imaging (fMRI) at the 2 weeks visit. The CogState neuropsychological battery was used to assess generalisation of learning to non-trained task from baseline to week 2 visit. fMRI was used to assess the mechanism of improved cognitive performance during working memory assessment. Behavioural data analyses were conducted by specification of multilevel regression models and multiple regressions for training and generalisation effects, respectively. fMRI data analyses were conducted with general linear models. Results: tDCS differentially improved some cognitive deficits when applied as an adjunct to cognitive training. Namely, tDCS facilitated performance on a working memory task, and this improvement was maintained for up to four weeks. No effect of stimulation on implicit learning could be discerned. Generalisation of learning was observed on tasks similar to the domain of working memory, i.e. attention and vigilance and working memory indexed by the CogState neuropsychological battery. fMRI data demonstrated that tDCS reduced activation in temporo-parietal cortex in the real stimulation group during working memory assessment. Discussion: Given the current lack of effective therapies for these serious cognitive functioning deficits on both social functioning and self-reported quality of life in schizophrenia, tDCS offers an important and novel approach to modulating brain networks in order to ameliorate these cognitive deficits.
Supervisor: Shergill, Sukhwinder S. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available