title: Long-term cognitive correlates of traumatic brain injury across adulthood and interactions with APOE genotype, sex, and age cohorts.
abstract: There is continuing debate about long-term effects of brain injury. We examined a range of traumatic brain injury (TBI) variables (TBI history, severity, frequency, and age of injury) as predictors of cognitive outcome over 8 years in an adult population, and interactions with apolipoprotein E (APOE) genotype, sex, and age cohorts. Three randomly sampled age cohorts (20-24, 40-44, 60-64 years at baseline; N = 6333) were each evaluated three times over 8 years. TBI variables, based on self-report, were separately modeled as predictors of cognitive performance using linear mixed effects models. TBI predicted longitudinal cognitive decline in all three age groups. APOE ε4 + genotypes in the young and middle-aged groups predicted lower baseline cognitive performance in the context of TBI. Baseline cognitive performance was better for young females than males but this pattern reversed in middle age and old age. The findings suggest TBI history is associated with long-term cognitive impairment and decline across the adult lifespan. A role for APOE genotype was apparent in the younger cohorts but there was no evidence that it is associated with impairment in early old age. The effect of sex and TBI on cognition varied with age cohort, consistent with a proposed neuroprotective role for estrogen.
authors.affiliation: 1 Centre for Research on Aging, Health and Wellbeing, Australian National University, Australia.
authors.forename: Ranmalee
authors.initials: R
authors.lastname: Eramudugolla
authors.affiliation: 2 Department of Human Development & Family Studies, Colorado State University, Fort Collins, Colorado.
authors.forename: Allison A M
authors.initials: AA
authors.lastname: Bielak
authors.affiliation: 3 Institute of Psychological Sciences, Faculty of Medicine and Health, University of Leeds, Leeds, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Bunce
authors.affiliation: 4 John Curtin School of Medical Research, Australian National University, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: Easteal
authors.affiliation: 1 Centre for Research on Aging, Health and Wellbeing, Australian National University, Australia.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Cherbuin
authors.affiliation: 1 Centre for Research on Aging, Health and Wellbeing, Australian National University, Australia.
authors.forename: Kaarin J
authors.initials: KJ
authors.lastname: Anstey
mesh_terms: D000328:Adult; D000375:Aging; D001057:Apolipoproteins E / Q000235:genetics*; D001930:Brain Injuries / Q000150:complications* / Q000235:genetics*; D003072:Cognition Disorders / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D005838:Genotype; D006801:Humans; D016014:Linear Models; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D011237:Predictive Value of Tests; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D001057:Apolipoproteins E