Head trauma and in vivo measures of amyloid and neurodegeneration in a population-based study

Abstract

Objectives: We determined whether head trauma was associated with amyloid deposition and neurodegeneration among individuals who were cognitively normal (CN) or had mild cognitive impairment (MCI).

Methods: Participants included 448 CN individuals and 141 individuals with MCI from the Mayo Clinic Study of Aging who underwent Pittsburgh compound B (PiB)-PET, fluorodeoxyglucose-PET, and MRI. Head trauma was defined as a self-reported brain injury with at least momentary loss of consciousness or memory. Regression models examined whether head trauma was associated with each neuroimaging variable (assessed as continuous and dichotomous measures) in both CN and MCI participants, controlling for age and sex.

Results: Among 448 CN individuals, 74 (17%) self-reported a head trauma. There was no difference in any neuroimaging measure between CN subjects with and without head trauma. Of 141 participants with MCI, 25 (18%) self-reported a head trauma. MCI participants with a head trauma had higher amyloid levels (by an average 0.36 standardized uptake value ratio units, p = 0.002).

Conclusions: Among individuals with MCI, but not CN individuals, self-reported head trauma with at least momentary loss of consciousness or memory was associated with greater amyloid deposition, suggesting that head trauma may be associated with Alzheimer disease-related neuropathology. Differences between CN individuals and individuals with MCI raise questions about the relevance of head injury-PET abnormality findings in those with MCI.

Figure. PiB-PET, FDG-PET, and adjusted hippocampal volume by cognitive status and history of head trauma

Box plots with superimposed data points for PiB-PET (A), FDG-PET (B), and adjusted hippocampal volume (C). The p values indicate the difference between those with and without head trauma based on linear regression models adjusted for age and sex. Boxes indicate the median and quartiles, with vertical “whiskers” extending to the nearest data point within 1.5 times the value of the interquartile range. CN = cognitively normal; FDG = fluorodeoxyglucose; MCI = mild cognitive impairment; PiB = Pittsburgh compound B; SUVR = standardized update value ratio.