Impact of aging on the immune response to traumatic brain injury (AIm:TBI) study protocol

Telomere Length Associates With Symptom Severity After Mild Traumatic Brain Injury in Older Adults

The objectives were to compare differences in telomere length (TL) among younger (21-54 years) and older adults (≥55) with mild traumatic brain injury (mTBI) to non-injured controls and to examine the association between TL and the severity of post-concussive symptoms over time. We performed a quantitative polymerase chain reaction to determine the TL (Kb/genome) of peripheral blood mononuclear cell samples (day 0, 3 months, and 6 months) from 31 subjects. The Rivermead Post-Concussion Symptoms Questionnaire was used to assess symptoms. Group-by-time comparisons of TL and symptom severity were evaluated with repeated-measures analysis of variance. Multiple linear regression examined the relationship between TL, group (mTBI and non-injured controls), and symptom severity total and subscale scores. Significant aging-related differences in TL were found within mTBI groups by time (day 0, 3 months, and 6 months; p = 0.025). Older adults with mTBI experienced significant worsening of changes in total symptom severity scores over time (day 0, 3 months, and 6 months; p = 0.016). Shorter TLs were associated with higher total symptom burden among each of the four groups at day 0 (baseline; p = 0.035) and 3 months (p = 0.038). Shorter TL was also associated with higher cognitive symptom burden among the four groups at day 0 (p = 0.008) and 3 months (p = 0.008). Shorter TL was associated with higher post-injury symptom burden to 3 months in both older and younger persons with mTBI. Large-scale, longitudinal studies of factors associated with TL may be useful to delineate the mechanistic underpinnings of higher symptom burden in adults with mTBI.

Factors Associated with the Development of Persistent Pain after mTBI

BACKGROUND

Persistent pain after mild traumatic brain injury (mTBI) is widely experienced, yet little is known about who is at risk for experiencing persistent pain after their injury.

AIMS

The purpose of this study was to 1) determine if there are factors associated with later experiencing persistent pain after mTBI and 2) examine if there are symptom patterns associated with the experience of persistent pain.

DESIGN

Secondary analysis was conducted using de-identified data from an NIH-funded longitudinal study.SettingsParticipants were enrolled in the emergency department.

PARTICIPANTS

Participants were aged 21 to 92 and all had experienced mTBI.

METHODS

We examined baseline characteristics, symptoms, and injury related variables associated with the endorsement of persistent pain among those with mTBI (N = 183) from baseline to 6 months post-injury. In order to identify a persistent pain phenotype, exploratory factor analysis was used to determine which symptoms co-occur with persistent pain.

RESULTS

Persistent pain was found in 78% of those with mTBI. Those with lower overall health status at day 7 and at 1-month following injury had greater odds of developing persistent pain. Those with higher levels of general health status and physical function health status at day 7 and 1 month, and those with higher levels of overall health related status at 1 month had significantly lesser odds of persistent pain at 6 months. Factor analysis revealed that persistent pain and co-occurring symptoms (anxiety, depression, dizziness, nausea and vomiting, sleep disturbance, poor memory, poor concentration, longer to think and light sensitivity) loaded on one factor, indicating that these symptoms are associated.

CONCLUSIONS

Those at increased risk for persistent pain should be screened beginning early in the recovery trajectory to reduce their risk of developing persistent pain. Identification of a phenotype offers potential for recognition of symptoms that cluster with persistent pain, improving the ability to treat patients more holistically, and develop interventions to support recovery from injury.

Plasma Phospholipid Metabolites Associate With Functional Outcomes Following Mild Traumatic Brain Injury in Older Adults

OBJECTIVE

To compare differences using a metabolomics approach in older adults (≥55) with mild traumatic brain injury (mTBI) to control adults and to identify a signature profile related to functional outcome 3-6 months post-injury.

METHODS

We performed metabolomics analysis using LC-MS of untargeted aqueous metabolites on plasma samples taken from a parent prospective cohort study. Older adults with mTBI (n = 14) were purposively sampled to include participants with worsening (decrease in GOS-E of at least 1 level) and improved (increase in GOS-E of at least 1 level) outcomes from 3 to 6 months. The data were analyzed using PLS-DA with VIP scores, Random Forest, and spline fit between the different groups as a function of time for exposure on outcome.

RESULTS

Separation of comparisons were seen at 24 hours (negative ionization) and 6 months (positive ionization), revealing two metabolites of interest, phosphatidylcholine and phosphatidylethanolamine. Phosphatidylcholine levels were higher in those with mTBI compared to controls (p < 0.05), while lower concentration of phosphatidylethanolamine was seen in those with mTBI compared to controls (p < 0.05). Phosphatidylinositol-3,4,5-trisphosphate was significant in those with mTBI compared to controls (n = 10) based on improved (n = 6) versus worsened (n = 8) outcomes from 3 to 6 months.

CONCLUSION

We identified plasma metabolites related to phospholipid metabolism in older adults following mTBI and associated with long-term functional outcome. These findings may underly pathological mechanisms of outcome differences in older adults who experience mTBI.