APOE ε4 allele status modulates the spatial patterns of progressive atrophy in the temporal lobes after mild traumatic brain injury

Abstract

Abstract INTRODUCTION We evaluated how the apolipoprotein E (APOE) ε4 allele modulated the spatial patterns of longitudinal atrophy in the Alzheimer's disease–vulnerable brain areas of patients with mild traumatic brain injury (mTBI) from the acute to chronic phase post injury. METHODS Fifty‐nine adult patients with acute mTBI and 48 healthy controls with APOE ε4 allele testing underwent T1‐weighted magnetic resonance imaging and neuropsychological assessments with 6 to 12 months of follow‐up. Progressive brain volume loss was compared voxel‐wise in the temporal lobes. RESULTS Patients with the APOE ε4 allele presented significant longitudinal atrophy in the left superior and middle temporal gyri, where the progressive gray matter volume loss predicted longitudinal impairment in language fluency, whereas mTBI APOE ε4 allele noncarriers showed mainly significant longitudinal atrophy in the medial temporal lobes, without significant neuropsychological relevance. DISCUSSION The atrophy progression observed in mTBI patients with the APOE ε4 allele may increase the possibility of developing a specific phenotype of Alzheimer's disease with language dysfunction. Highlights The apolipoprotein E (APOE) ε4 allele and mild traumatic brain injury (mTBI) are risk factors for Alzheimer's disease (AD) progression. It is unclear how the interaction of mTBI with the APOE ε4 allele impacts the progressive atrophy topography in AD‐vulnerable brain regions. In this study, patients with the APOE ε4 allele showed progressive atrophy patterns similar to the early stage of logopenic variant of primary progressive aphasia (lvPPA) phenotype of AD. APOE ε4 allele carriers with mTBI history may be at the risk of developing a given AD phenotype with language dysfunction.

Keywords

• Alzheimer's disease risk
• APOE ε4 allele status
• longitudinal atrophy
• mild traumatic brain injury
• temporal lobes