Dissertation
Predicting cognitive outcomes after developmental-onset focal brain injury: the contribution of age at lesion onset
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2024
DOI: 10.25820/etd.007761
Abstract
The study of cognitive functioning following brain damage has been a pillar of neuropsychological research for decades. A review of the literature indicates age, injury, demographic, and social/environmental variables are all relevant in the prediction of cognitive outcomes after brain injury. This body of work aims to investigate cognitive outcomes after focal brain injury, with a special emphasis on the influence of age at lesion onset on cognitive outcomes. To this aim, the first study investigated academic skills outcomes after brain injury and identified the influence of age and injury variables across the lifespan. The sample included
651 participants with focal brain lesions. Math, reading, and spelling data from the Wide Range Achievement Test (WRAT) were used as the academic skills outcomes. Age at lesion onset ranged from 0 to 85 years old. Linear regressions were conducted to identify the relation between age and injury variables and academic skills outcomes. Lesion-symptom mapping was conducted to identify the brain areas that, when lesioned, were associated with deficits in academic skills. A quadratic model of age of lesion onset significantly predicted math, reading, and spelling outcomes, while accounting for various covariates. Education, sex, lesion size and laterality, etiology, and seizure history were additional predictors of academic skills outcomes across the lifespan. Academic skill deficits were associated with damage to various brain areas across the left-hemisphere frontal, temporal, and parietal lobes, the insular area, and left- and right-hemisphere white matter. This first study supports age of lesion onset as a relevant predictor of academic skills after brain injury in a lifespan sample. Several other variables (e.g., education, sex, lesion characteristics, and seizure history) were notable in the prediction of outcomes across the lifespan.
The second study investigated cognitive outcomes after developmental-onset focal brain injury. The sample included 158 participants with focal brain lesions and age of lesion onset ranging from 0-25 years old. Linear regressions were conducted to identify the relation between age at lesion onset and outcomes, while accounting for lesion volume and a history of epilepsy. Ridge and LASSO regressions were conducted to further investigate larger models of predictors for cognitive outcomes after early-onset brain injury while including age, injury, and social and environmental variables. The sample had significantly lower scores than the population test means on measures of attention and working memory, processing speed, verbal memory, visual memory, executive functioning, language, and academic skills. Age at lesion onset significantly predicted outcomes in executive functioning, while accounting for lesion volume and a history of epilepsy. Earlier age at onset was associated with worse outcomes. Overall, age at lesion onset is a relevant variable for predicting executive outcomes in an extended developmental cohort. The results also indicated outcomes after developmental-onset brain injury are influenced by age, injury, demographic, and social and environmental variables.
The third study examined the utility of lesion-symptom maps derived from persons with adult-onset lesions for predicting executive function outcomes based on lesion location for persons with developmental-onset focal brain injuries. Lesion locations associated with worse performance in executive function outcomes for adults significantly predicted executive function outcomes based on lesion location for individuals with onset in the developmental period. Additionally, when lesion-symptom mapping was conducted in developmental-onset samples, the lesion locations associated with worse executive function outcomes were similar to the locations identified for individuals with adult-onset brain injuries. Overall, it appears there is consistency in lesion locations relevant for predicting executive function outcomes across adults and development.
Together, these studies expand the age at lesion onset literature with potential for implications in both academic and clinical realms (e.g., furthering understanding of brain-behavior relationships and aiding in identifying individuals at increased risk for poor outcomes after focal brain injury). Findings from these studies indicate age at lesion onset is a relevant variable when predicting cognitive outcomes and earlier onset often confers increased risk for worse outcomes. However, these findings are not indicative of the risk for poor cognitive outcomes when compared to normative expectations. It is always important to contextualize findings by identifying if significant differences between sample means and expected outcomes are also potentially clinically meaningful. Future work could benefit from larger developmental samples, longitudinal designs, and more diverse samples to build on past work and expand on current understanding of predictors of cognitive outcomes after developmental-onset brain injury.
Details
- Title: Subtitle
- Predicting cognitive outcomes after developmental-onset focal brain injury: the contribution of age at lesion onset
- Creators
- Alyssa W Sullivan
- Contributors
- Daniel Tranel (Advisor)Aaron Boes (Committee Member)Ece Demir-Lira (Committee Member)Amanda McCleery (Committee Member)Emily Thomas (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Psychology
- Date degree season
- Summer 2024
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.007761
- Number of pages
- xi, 153 pages
- Copyright
- Copyright 2023 Alyssa W Sullivan
- Grant note
- The first study was supported in part by a National Institutes of Health Behavioral-Biomedical Interface T32 Predoctoral Training Grant (T32GM108540) from the National Institute of General Medical Sciences for Alyssa Sullivan and the Kiwanis Neuroscience Research Foundation for Daniel Tranel. (ii)
- Language
- English
- Date submitted
- 06/12/2024
- Description illustrations
- illustrations
- Description bibliographic
- Includes bibliographical references (pages 134-153).
- Public Abstract (ETD)
It is well known that many factors influence how well a person recovers after brain injury. This body of work investigates variables that influence recovery after brain injury with a special focus on the age at which a person sustains a brain injury. The first study included a sample of individuals who sustained brain injury across the lifespan. Results indicated brain injury during very early or later life was associated with better academic skills (e.g., math, reading, spelling) outcomes when compared to brain injury during the middle years. The second study included a sample of individuals with early brain injury (0-25 years). Age at time of brain injury was also important for predicting outcomes for executive functioning in this sample. Earlier brain injury predicted worse executive functioning outcomes. Variables related to age, injury (size, side, a history of epilepsy), demographic, and social/environmental are all relevant when considering how someone may recover after brain injury. Location of the damage in the brain is also a relevant variable when considering recovery after brain injury. The third study identified areas of the brain, that when damaged, are associated with worse executive functioning skills in adults are similar to brain areas associated with executive function outcomes when injury occurs earlier in life. However, there are likely more nuanced changes across development. In general, future work would benefit from building on findings from these studies in larger and more diverse samples of developmental patients.
- Academic Unit
- Psychological and Brain Sciences
- Record Identifier
- 9984698153002771
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