mTBI brain abnormalities mirror Alzheimer dementia

Utilizing diffusion tensor imaging (DTI), researchers have correlated post-concussion symptoms with abnormalities in the posterior gray matter-white matter junction, most prominently in the auditory cortex, according to a study published online June 18 in Radiology.

Notably, the distribution of abnormalities in the white matter of concussion patients strongly resembled findings in patients with Alzheimer dementia, reported Saeed Fakhran, MD, of the University of Pittsburgh School of Medicine, and colleagues.

“Numerous prior studies have shown the important role of [DTI] in evaluating white matter integrity after mild TBI and white matter abnormalities in patients with mild TBI relative to control subjects. Other studies have correlated postconcussive cognitive dysfunction with focal white matter abnormalities. However, few studies have attempted to correlate MR abnormalities with patient-reported symptoms,” wrote the authors.

A total of 64 consecutive patients with mild traumatic brain injury (mTBI) who underwent DTI with conventional MR imaging were retrospectively evaluated. Fractional anisotropy (FA) maps were generated and compared with neurocognitive evaluations to determine correlation with symptoms.

Concussion symptom scores varied from two to 97, with a mean of 32.7, reported Fakhran and colleagues. Thirty-four patients demonstrated sleep and wake disturbances. High concussion symptom score was correlated with reduced FA in the auditory cortex. Results also showed FA was significantly decreased in the parahippocampal gyri of patients with sleep and wake disturbances compared with patients without such disturbances.

Fakhran and colleagues noted that the earliest affected neurons in Alzheimer dementia also reside in the parahippocampal region and that degeneration is predominantly seen in subcortical white matter posteriorly. The symptomatic abnormalities in the current study closely mirror the losses seen in Alzheimer dementia, and the authors noted that sleep and wake disturbances are among the earliest findings in Alzheimer dementia.  

“Although our results are preliminary, they suggest that symptomatic findings in patients with mild TBI may not be the result of the direct neuronal or axonal injury but rather a neurodegenerative cascade whose initiating event is trauma,” wrote the authors.

They suggested that the findings may help direct future research strategies.