Date of Award

Summer 8-15-2015

Author's School

Graduate School of Arts and Sciences

Author's Department

Psychology

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Although children born very preterm (VPT, <33 weeks gestational age) are 2–3 times more likely to receive a diagnosis of ADHD in childhood than full term children, the nature and extent of their attention problems is not well understood. Furthermore, little is known about the mechanisms that place VPT children at increased risk of attention impairment. Previous research has shown strong links between white matter abnormalities and adverse motor and cognitive outcomes, but not for attention. This suggests that the mechanism for inattention may be different in this group. Thus, the aims of the current study were 1) to describe the nature and extent of attention problems in VPT children, 2) to document regional structural alterations in grey matter volume between VPT and full term children, and 3) to relate attention outcomes to regional grey matter volumes in VPT children at age 12 years. As part of a prospective longitudinal study, VPT children (n = 110) and full term control children (n = 113) underwent a neurodevelopmental assessment and structural MRI scan at age 12 years. Key attention outcomes included selective, sustained, and executive attention; assessed with the Test of Everyday Attention for Children and adjusted for social background risk. To examine associations between very preterm birth and grey matter development, structural T1-weighted images were analyzed for all study children using optimized voxel based morphometry (FWE-corrected p<0.05), adjusted for age at scan and social background characteristics. Modulated gray matter volume values were then extracted from key brain regions and related to measures of attention within the VPT group. At age 12 years, VPT children were characterized by poorer sustained (ps≤.03) and executive attention (ps≤.01) compared to full term children. Group differences in executive attention remained after adjustment for social background risk (ps≤.02). VPT children evidenced reduced grey matter volume in the bilateral parietal, temporal, left prefrontal, and posterior cingulate cortices; bilateral thalami, and bilateral hippocampus (FWE-corrected p<0.05). Increased grey matter volume was also found in the medial occipital and anterior cingulate cortices (FWE-corrected p<0.05). Within the VPT group, thalamic volume was correlated with selective attention (r = -.34) and executive shifting attention (r = .32); medial occipital volume correlated with sustained response inhibition (r = .24); and volumes in the thalami (r = -.36) and left temporal (r = -.35), posterior cingulate (r = -.36) and occipital cortices (r = -.30) correlated with executive divided attention. Reduced grey matter volume in the occipital (p = .05) and posterior cingulate (p = .006) regions at age 12 years independently predicted attention after taking into account the infant clinical, neuropathological and social factors also related to attention outcomes. Findings indicate that VPT children experience lapses in attention, difficulty shifting attentional focus, and problems with multitasking. The structural abnormalities identified in regional grey volume at age 12 years suggests that grey matter growth and development is vulnerable to the consequences of very preterm birth. Importantly, regional grey matter volume was deferentially and independently associated with attention abilities in VPT children, highlighting grey matter growth and development as an important neural mechanism for attention in VPT children. The findings of the current study raise concerns for the longer term neurological development of children born very preterm, while also emphasizing the need for tailored educational support services that addresses the attention problems of this group as they transition into higher level education during their early teenage years.

Language

English (en)

Chair and Committee

Lori Markson

Committee Members

Deanna Barch, Cynthia Rogers, Desiree White

Comments

Permanent URL: https://doi.org/10.7936/K7P55KRZ

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