Traumatic brain injury research update

June 07, 2019

The relationship between depression, traumatic brain injury (TBI), injury severity measures and associated patient outcomes is complex and the subject of much study. In this article, Mayo Clinic physiatrist Allen W. Brown, M.D., director of brain rehabilitation research at Mayo Clinic's campus in Rochester, Minnesota, provides an overview of three recently published studies focusing on this important vein of research.

Impact of pharmacological treatment of depression

Depression is a known risk factor for prolonged recovery after TBI. Symptoms associated with mild and concussive TBI typically resolve within a week to several months. There's ample evidence that individuals who experience depression after TBI are at increased risk of chronic symptoms, increased use of health care resources and poor health‐related outcomes. Data obtained via systematic reviews have also demonstrated that concussive TBI can increase an individual's risk of developing mental health disorders, and that a history of mental health problems has also been associated with poorer outcomes after concussive injury.

Building upon these findings, Mayo Clinic researchers conducted a study to examine whether pharmacological treatment of depression at injury in patients diagnosed with mild or concussive TBI is associated with fewer subsequent clinician visits for persistent injury‐related symptoms. The results from this study were published in PM&R in 2018.

The research team performed a retrospective medical record review to identify 120 Mayo Clinic patients who were diagnosed with depression and mild TBI, or depression and concussive TBI, from Jan. 1, 2000, to June 10, 2015, who met the selection criteria. Those patients were separated into two groups: those who were treated with a Food and Drug Administration-approved oral medication for depression at the time of TBI and those who were not.

Researchers recorded the number of clinician visits for post-injury symptoms occurring at three, six, and 12 months post-injury. They also examined whether covariates of age, gender, mechanism of injury, injury severity and education influenced the number of visits at each time point, beyond their treatment for depression.

Results and conclusions

The group that was treated for depression at the time of injury had significantly fewer clinician visits for persistent injury‐related symptoms at all three time points than did the group that was not treated for depression. Depression treatment remained predictive of the number of clinician visits, even after researchers accounted for differences in age and injury severity.

College education was predictive of a higher number of visits at all time points in the sample over the first year post-injury. These findings are consistent with other studies showing that higher education is associated with increased health care usage.

According to Dr. Brown, the study's senior author, these results are consistent with multiple studies considering the effects of depression on mild or concussive TBI symptom severity and duration, and they have implications for improving patient outcomes and controlling related health care costs.

"We know that both depression and concussion are associated with substantial health‐related costs in the United States, and that the incidence of mild and concussive TBI in our nation is high," says Dr. Brown. "Identifying and addressing any factors that prolong recovery and increase health care visits could help us substantially reduce health care costs associated with these conditions. These results suggest that TBI prevention initiatives, routine depression screening and the effective management of mood disorders in patients who are at risk of or newly diagnosed with TBI are an important part of these efforts."

Relationship between injury severity and depressive symptoms

In another Mayo Clinic-led study, researchers explored the connections between injury severity and depressive symptoms for treatment-seeking individuals with TBI. The results from this study were published in the Journal of Clinical Psychology in Medical Settings in 2019.

Researchers classified TBI severity in 72 participants who completed the Patient Health Questionnaire at admission and at dismissal from rehabilitation, using the Mayo Classification System.

Results and conclusions

Patients with mild TBI reported more depressive symptoms at admission and at dismissal than did those with moderate or severe TBI.

Although injury severity groups differed by gender composition, gender had no effect on severity of depressive symptoms.

All participants reported fewer depressive symptoms at dismissal from rehabilitation, including lower endorsement of dysphoria by discharge.

Participants with mild TBI continued to report mildly severe depressive symptoms at dismissal, as well as residual problems with anhedonia.

"These findings demonstrate that providing interdisciplinary post-acute rehabilitation services for people with TBI of any severity, including those with mild injury, has measurable benefits," says Dr. Brown, a co-author for the article published in the Journal of Clinical Psychology in Medical Settings.

Indicators of injury severity

In another Mayo-led study, researchers sought to examine the predictive relationship between an objective indicator of injury severity — the adapted Marshall computerized tomography (CT) classification scheme — and any of the following: clinical indicators of injury severity in the acute phase, functional outcomes at inpatient rehabilitation discharge, and functional and participation outcomes at one year after injury, including death, in people with TBI. Results from this study were published in Brain Injury in 2019.

To perform this analysis, researchers identified 4,895 individuals who received inpatient rehabilitation following acute hospitalization for TBI and were enrolled in the Traumatic Brain Injury Model Systems National Database between 1989 and 2014. The research team used head CT variables to place each individual into adapted Marshall CT classification categories I through IV. They also developed prediction models to determine the amount of variability explained by the CT classification categories, identifying commonly used predictors, including a clinical indicator of injury severity.

Results and conclusions

Analysis of the findings suggests that the adapted Marshall classification categories made no meaningful contribution to variance in the multivariable models predicting outcomes at any time point after injury. The classification categories aided only in the prediction of craniotomy or craniectomy during acute hospitalization.

"Our results suggest that head CT findings classified in this manner do not inform clinical discussions related to functional prognosis or rehabilitation planning after TBI," explains Dr. Brown, the lead author for the article published in Brain Injury. "These results are relevant for research methodology and measurement selection because they indicate that the method of classifying head CT findings used in this study should not be used for long-term outcome prediction or for determination of treatment benefits following the types of injuries as those of our study participants."

For more information

Kruse RC, et al. Pharmacologic treatment for depression at injury is associated with fewer clinician visits for persistent symptoms after mild traumatic brain injury: A medical record review study. PM&R. 2018;10:898.

Powell MR, et al. Injury severity and depressive symptoms in a post-acute brain injury rehabilitation sample. Journal of Clinical Psychology in Medical Settings Journal of Clinical Psychology in Medical Settings. In press.

Brown AW, et al. Predictive utility of an adapted Marshall head CT classification scheme after traumatic brain injury. Brain Injury. In press.