Table 3.
TBI Participants: Sample Characteristics by ε4 Allele Group (N = 79)
| ε4 allele present (ε4+) (n = 18) | ε4 allele absent (ε4–) (n = 61) | ||||
|---|---|---|---|---|---|
| Variables | M | SD | M | SD | p valuea |
| Age | 33.56 | 7.94 | 32.10 | 6.81 | 0.445 |
| Education (years) | 13.50 | 1.30 | 14.13 | 1.62 | 0.134 |
| WRAT4 Reading SS | 100.17 | 8.42 | 101.20 | 11.63 | 0.727 |
| Months since most recent TBI | 56.72 | 37.96 | 67.55 | 51.08 | 0.408 |
| Months since most sig. TBI | 67.11 | 42.48 | 79.08 | 54.78 | 0.397 |
| Age at most sig. TBI | 28.22 | 7.35 | 25.82 | 5.86 | 0.154 |
| Number of TBIs sustained | 2.17 | 1.34 | 2.44 | 1.39 | 0.457 |
| N | % | N | % | p valueb | |
|---|---|---|---|---|---|
| Sex | |||||
| Male | 15 | 83.3 | 52 | 85.2 | 0.843 |
| Female | 3 | 16.7 | 9 | 14.8 | |
| Ethnicity | |||||
| White | 6 | 33.3 | 26 | 42.6 | 0.439 |
| Hispanic | 7 | 38.9 | 21 | 34.4 | |
| Black | 4 | 22.2 | 5 | 8.2 | |
| Asian/Pacific Islander | 1 | 5.6 | 8 | 13.1 | |
| Other | 0 | 0 | 1 | 1.6 | |
| Married/cohabitating | |||||
| Yes | 6 | 33.3 | 23 | 37.7 | 0.819 |
| No | 11 | 61.1 | 37 | 60.7 | |
| Missing | 1 | 5.6 | 1 | 1.6 | |
| Currently employed | |||||
| Yes | 7 | 38.9 | 29 | 47.5 | 0.481 |
| No | 11 | 61.1 | 31 | 50.8 | |
| Missing | 0 | 0 | 1 | 1.6 | |
| Branch of service | |||||
| Air Force | 0 | 0 | 6 | 9.8 | 0.277 |
| Army | 3 | 16.7 | 16 | 26.2 | |
| Marines | 6 | 33.3 | 22 | 36.1 | |
| Navy | 9 | 50.0 | 16 | 26.2 | |
| Other | 0 | 0 | 1 | 1.6 | |
| OEF/OIF/OND veteran | |||||
| Yes | 18 | 100.0 | 56 | 91.8 | 0.209 |
| No | 0 | 0 | 5 | 8.2 | |
| Combat exposure | |||||
| Yes | 10 | 55.6 | 44 | 72.1 | 0.184 |
| No | 8 | 44.4 | 17 | 27.9 | |
| TBI severity | |||||
| Mild | 15 | 83.3 | 54 | 88.5 | 0.561 |
| Moderate | 3 | 16.7 | 7 | 11.5 | |
| LOC (most sig. TBI) | |||||
| Yes | 9 | 50.0 | 40 | 65.6 | 0.232 |
| No | 9 | 50.0 | 21 | 34.4 | |
| AOC (most sig. TBI) | |||||
| Yes | 9 | 50.0 | 21 | 34.4 | 0.232 |
| No | 9 | 50.0 | 40 | 65.5 | |
| PTA (most sig. TBI) | |||||
| Yes | 10 | 55.6 | 33 | 54.1 | 0.423 |
| No | 8 | 44.4 | 22 | 36.1 | |
| Unsure | 0 | 0 | 5 | 8.2 | |
| Missing | 0 | 0 | 1 | 1.6 | |
| Lifetime diagnosis: MDDc | |||||
| Yes | 8 | 50.0 | 20 | 39.2 | 0.445 |
| No | 8 | 50.0 | 31 | 60.8 | |
| Lifetime diagnosis: PTSDc | |||||
| Yes | 8 | 53.3 | 23 | 45.1 | 0.574 |
| No | 7 | 46.7 | 28 | 54.9 |
Independent-samples t-tests were used to determine whether there were group differences for age, education, WRAT4 Reading, time from most recent TBI to testing, time from most significant TBI to testing, age at most significant TBI, and lifetime number of TBIs.
Chi-square analyses were used to determine whether there were group differences for sex, ethnicity, marital status, employment status, military branch of service, OEF/OIF/OND status, combat exposure, TBI severity, presence of LOC, presence of AOC, presence of PTA, lifetime diagnosis of MDD, and lifetime diagnosis of PTSD.
Lifetime diagnosis of MDD and PTSD were gathered through one-on-one interview using the Mini-International Neuropsychiatric Interview (M.I.N.I.; Sheehan and colleagues, 2006). Further, M.I.N.I. data were not available for all participants; MDD diagnostic information was available for 67 of the 79 TBI participants, and PTSD diagnostic information was available for 66 of the 79 TBI participants.
WRAT4, Wide Range Achievement Test 4; SS, standard score; TBI, traumatic brain injury; sig., significant; OEF, Operation Enduring Freedom; OIF, Operation Iraqi Freedom; OND, Operation New Dawn; LOC, loss of consciousness; AOC, alteration of consciousness; PTA, post-traumatic amnesia; MDD, Major Depressive Disorder; PTSD, post-traumatic stress disorder; M, mean; SD, standard deviation.