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The contribution of sleep to cognitive function in children with epilepsy

Chan, Samantha Yuen-Sum; (2017) The contribution of sleep to cognitive function in children with epilepsy. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Cognitive impairment is the major co-morbidity in childhood epilepsy, and in many cases will have a larger long-term impact than the seizures themselves. However, the mechanisms contributing to this are poorly understood, precluding targetted intervention. Sleep is crucial for intelllectual functioning. Yet sleep in children with epilepsy, and its impact on intellectual function has scarcely been studied. This thesis aims to examine the structure and regulation of sleep in children with epilepsy, and to provide direct evidence of the impact of sleep on cognitive function by correlating neurophysiological characteristics with performance on sleep dependent neuropsychological tasks administered over the same interval as the sleep recorded. To examine sleep architecture in children with epilepsy, I developed a modified system for visual sleep scoring, taking into account nocturnal seizures and interictal activity. This was validated in a pilot sample, then applied to the scoring of 52 recordings from children with epilepsy. Based on established memory consolidation tasks and open-source psycholinguistic data, I developed and piloted a memory consolidation task battery suitable for testing school-aged English-speaking children, comprising parallel versions of a visuospatial and a verbal task. With these tools, I performed a prospective, within-subject comparison of memory retention across similar length intervals with or without sleep, in order to determine the contribution of sleep to memory consolidation. I compared results from patient (n=22) and healthy control (n=21) samples, finding – contrary to expectations – that sleep benefits memory consolidation in children with epilepsy to the same degree as controls. However, the benefit of sleep showed an inverse relationship to the nocturnal interictal discharge load. I also employed quantitative EEG analysis of slow wave activity to examine sleep homeostasis in patients with epilepsy, studying a retrospective sample (n=16) who had undergone partial sleep deprivation. Sleep homeostasis was fundamentally intact in these patients, who had similar clinical characteristics to the prospective sample. Findings from this thesis provide the first direct evidence that sleep benefits intellectual functioning in children with epilepsy, particularly where its structure and regulation is intact. Sleep-related memory consolidation may represent a compensatory mechanism, perhaps accounting for the relative cognitive preservation in this cohort of children with epilepsy with a structural aetiology, despite the early onset of seizures.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The contribution of sleep to cognitive function in children with epilepsy
Event: University College London
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Third party copyright material has been removed from ethesis.
Keywords: Epilepsy, Cognition, Sleep, Memory consolidation, Sleep homeostasis, Childhood epilepsy
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Pop Health Sciences > UCL GOS Institute of Child Health
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Pop Health Sciences > UCL GOS Institute of Child Health > ICH Developmental Neurosciences Prog
URI: http://discovery.ucl.ac.uk/id/eprint/10024776
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