The Relationship Between TBI, Mild Cognitive Impairment, and All-Cause Dementia

Small- to moderate-sized associations have been reported with mild traumatic brain injury (TBI) and large-sized associations with moderate to severe TBI, in individuals with mild cognitive impairment (MCI) and all-cause dementia, according to study results presented at the 2023 American Academy of Neurology (AAN) Annual Meeting, held from April 22 to 27, in Boston, Massachusetts.

The original Framingham Heart Study (FHS) recruited its initial cohort — individuals who were between ages 30 and 62 years — from 1948 through 1950. In the population-based FHS, information regarding TBIs was obtained from self-reports and an in-depth review of medical records until a participant’s death.

The occurrence of TBI and the severity of TBI were effectuated via the use of modified American Congress of Rehabilitation Medicine and Veterans Affairs/ Department of Defense criteria, respectively. Consensus diagnoses for MCI, dementia, and AD dementia were effectuated with the use of modified Peterson criteria; the Diagnostic and Statistical Manual of Mental Disorders (DSM-4), 4th edition; and the National Institute of Neurological and Communicative Diseases and Stroke/AD and Related Disorders Association, respectively.

A total of 715 individuals who had experienced a TBI, along with 2145 sex- and age-matched control individuals without a TBI, were enrolled. Participants who had experienced a TBI were cognitively normal prior to the TBI. All participants were followed for an average of 16±17 years.

Researchers found that 567, 461, and 373 of participants without a TBI developed MCI, all-cause dementia, and AD dementia, respectively.

In contrast, 271, 218, and 131 of participants who had experienced a TBI developed MCI, all-cause dementia, and AD dementia, respectively.

In those with mild TBI, the following values were reported:

• MCI: hazard ratio (HR), 1.55; 95% CI, 1.14-2.12
• All-cause dementia: HR, 1.47; 95% CI, 1.02-2.14
• AD dementia: HR, 1.06; 95% CI, 0.68-1.66

In those with moderate to severe TBI, the following values were reported:

• MCI: hazard ratio (HR), 3.50; 95% CI, 1.10-11.17
• All-cause dementia: HR, 4.61; 95% CI, 0.96-22.14
• AD dementia: HR, 6.36; 95% CI, 0.72-56.50

Researchers concluded, “Association between mild TBI and dementia may be driven by non-AD etiologies.”