Traumatic Brain Injury and Alzheimer’s Disease

Brain Injury / Head Injury

By Steven J. Anglés

August 2, 2021

About 1.7 million people suffer traumatic brain injuries (TBIs) each year in the United States. These TBIs can be classified as mild (mTBI), moderate, or severe based on a number of neurological measures. The most common are mTBIs, or non-surgical TBIs in which most structural imaging studies show no appreciable damage, accounting for approximately 80% of all traumatic brain injuries yearly. For years, research studies have explored the effects that traumatic brain injury and Alzheimer’s disease each have on the human brain. In the past, studies have covered some similarities between neurodegeneration after acute mTBI, and neurodegeneration commonly associated with Alzheimer’s disease. However, a recent study published in the April 2021 issue of GeroScience directly compared the long-term effects of chronic mTBI to those of Alzheimer’s disease when it comes to the structure and function of the brain.[1] More importantly, the study focused on acute cognitive impairments after TBI as predictors of how likely it would be that a patient might develop changes in the brain that mirror those found in Alzheimer’s patients as they age. The study was conducted by researchers at the University of Southern California and funded by both the National Institutes of Health and the Department of Defense.

The study consisted of 33 participants that had suffered mTBI due to a fall, 66 participants that had already been diagnosed with Alzheimer’s disease, and another 81 participants with neither of these diagnoses. Researchers gathered data through imaging studies using a 3T MRI[2] , and then filtering the results through additional imaging methods including fluid-attenuated inversion recovery (FLAIR), susceptibility weighted imaging, and diffusion magnetic resonance imaging. Researchers then used these imaging results to observe differences in white matter and gray matter sections of the brains of all three participant groups.[3] In particular, researchers were interested in studying whether there were changes in the cortical thickness of participants with mTBI and then comparing those changes with cortical thickness changes in participants with Alzheimer’s disease.

Researchers in the study found reduced cortical thickness in several brain areas of both the mTBI and Alzheimer’s participants, but not among the “healthy” control group. The changes were most prominent in the frontal and temporal regions of the brain, but also in the occipital lobe. This is important because cortical thickness roughly correlates with a brain’s age, and thinning can often be associated with problems with decision-making, memory, attention, verbal fluency, processing new information, and a person’s ability to adapt behavior to new situations. By analyzing the way in which the white and gray matter in the brain degrade after mTBI, and by using advanced computerized techniques, researchers were encouraged in their ability to predict the severity of long-term brain changes by focusing first on the chronic stage of mTBI, using cognitive assessments taken soon after such injuries.

Ultimately, the study reinforced that both TBI and Alzheimer’s disease do indeed share common brain markers and trajectories as time goes on. The study further suggests that the extent of acute cognitive impairment shortly after trauma can predict the magnitude of long-term brain atrophy, which is itself associated with an increased risk for Alzheimer’s disease. The study also went on to note that the effects of chronic TBI in older individuals may be particularly severe, and may mimic the effects of advanced Alzheimer’s disease.

When handling insurance claims for victims of TBI, we must not only look backwards and establish where the patient has been in their recovery. It is equally important, if not more so, to look ahead in time and determine the long-term picture so the patient and their family can plan for residual challenges ahead in life. If you, your patients, or your staff would like any additional information on this topic, or others related to TBI, don’t hesitate to reach out. We are happy to assist however we can.


[1] Acute cognitive impairment after traumatic brain injury predicts the occurrence of brain atrophy patterns similar to those observed in Alzheimer’s disease Kenneth A. Rostowsky & Andrei Irimia & for the Alzheimer’s Disease Neuroimaging Initiative. GeroScience

[2] 3T, or 3 Tesla MRIs, use magnetic fields that are twice as powerful as the magnetic fields used in MRIs with a lower Tesla strength, resulting in faster, clearer and more complete images, including images of soft tissues and organs.

[3]Essentially, the brain’s gray matter controls how neurons communicate across short distances, and, white matter controls how neurons in the brain communicate across longer distances.