This 54-year-old Caucasian male trained in explosive ordinance disposal and served for 26 years on active military duty, including multiple deployments to Iraq and Afghanistan. He was employed a further 7 years as a contractor to a private defense company that focused on training bomb defusing teams. He reported at least 5 episodes of concussive injury to the head over his career, a TBI episode resulting in loss of consciousness in a parachuting accident in 2000, as well as exposure to hundreds of subconcussive blasts while acting as a team leader in Afghanistan defusing improvised explosive devices (IED). In 2007, he was involved in an IED attack where he was exposed to the blast while riding in a vehicle. He self-reported a slow deterioration in his cognition and memory beginning the year after the IED attack in 2007. Specifically, he reported significant memory difficulties and manifested a tremor in his hands. Self-reported symptoms were confirmed with his spouse due to his difficulty with memory.
As a part of his enrollment in a research trial, he underwent a neuropsychological test battery (Table 2) demonstrating significant cognitive impairment, including WAIS-IV Processing Speed Index (1st percentile), Trail Making Test A (<1st percentile), and Trail Making Test B (<1st Percentile).
MRI and PET results are shown in Figure 2. Quantitative analysis of the MRI scan demonstrates normal hippocampal, amygdala, and cerebral cortex volumes (Table 3). The [18F]AV-1451 PET scan demonstrates abnormal, intensely increased symmetric uptake primarily in the parietal and lateral occipital regions. There is also abnormally increased uptake in the orbitofrontal, posterior frontal, lateral temporal, and mesial temporal brain regions. The [11C]PiB PET scan demonstrates abnormally increased uptake in parietal, temporal and frontal lobes, as in Patient #1, a pattern characteristic of AD. Note there is negligible accumulation in the occipital lobes (as compared to the [18F]AV-1451 scan). The [18F]FDG PET scan shows abnormally and relatively symmetric decreased uptake in the posterior temporoparietal regions of the brain, with sparing of the frontal lobes. In summary, the [18F]AV-1451, [11C]PiB, and [18F]FDG PET scans demonstrate typical AD patterns of uptake.