Table 1.
Group mean ± standard deviation demographic, psychometric, and dependent measures for posttraumatic stress disorder (PTSD) and non-PTSD combat-exposed and combat-unexposed twin pairs.
| Measure | ExP+ (n = 12) | UxP+ (n = 21) | ExP− (n = 33) | UxP− (n = 32) |
|---|---|---|---|---|
| Age* | 47.9 ± 1.9 | 50.1 ± 4.8 | 49.5 ± 2.3 | 49.1 ± 2.2 |
| Combat Severity | 7.4 ± 2.4 | — | 3.5 ± 2.8 | — |
| CAPS Total | 49.4 ± 14.3 | — | 5.3 ± 7.3 | — |
| SCL-90-R GSI | 1.2 ± 0.6 | 0.4 ± 0.5 | 0.4 ± 0.5 | 0.3 ± 0.3 |
| SCL-90-R Depression | 1.3 ± 0.6 | 0.4 ± 0.6 | 0.5 ± 0.6 | 0.4 ± 0.4 |
| SCL-90-R Anxiety | 1.2 ± 0.9 | 0.3 ± 0.5 | 0.3 ± 0.4 | 0.2 ± 0.3 |
| Number of Trials | ||||
| 74 dB | 52.8 ± 14.2 | 56.0 ± 6.4 | 50.9 ± 10.1 | 52.6 ± 10.1 |
| 84 dB | 52.8 ± 13.7 | 54.9 ± 6.3 | 51.1 ± 10.5 | 53.8 ± 10.0 |
| 94 dB | 52.3 ± 14.1 | 55.8 ± 6.6 | 52.0 ± 10.0 | 52.6 ± 10.2 |
| 104 dB | 45.4 ± 15.4 | 51.6 ± 10.9 | 46.8 ± 13.1 | 46.8 ± 14.5 |
| P2 Slope | 0.30 ± 0.19 | 0.10 ± 0.20 | 0.17 ± 0.16 | 0.20 ± 0.24 |
| P2 Amplitude | ||||
| 74 dB | 4.7 ± 3.6 | 4.5 ± 2.7 | 4.7 ± 3.3 | 3.9 ± 2.8 |
| 84 dB | 8.2 ± 5.3 | 6.9 ± 3.2 | 6.9 ± 4.1 | 7.0 ± 4.3 |
| 94 dB | 10.0 ± 5.9 | 6.9 ± 4.9 | 7.9 ± 5.1 | 8.7 ± 5.6 |
| 104 dB | 13.9 ± 8.1 | 7.7 ± 7.6 | 10.0 ± 6.7 | 10.2 ± 8.8 |
| P2 Latency | ||||
| 74 dB | 207.3 ± 22.9 | 208.5 ± 21.5 | 206.8 ± 24.4 | 209.9 ± 18.7 |
| 84 dB | 199.7 ± 18.9 | 204.5 ± 15.1 | 202.7 ± 16.8 | 210.6 ± 16.0 |
| 94 dB | 202.8 ± 18.9 | 207.5 ± 17.7 | 202.3 ± 17.8 | 204.8 ± 16.9 |
| 104 dB | 200.5 ± 16.9 | 203.0 ± 17.1 | 204.2 ± 19.2 | 202.8 ± 16.9 |
*
Age as of October 1, 1997.
CAPS = Clinician-Administered PTSD Scale, ExP+ = combat-exposed twin with PTSD, ExP− = combat-exposed twin without PTSD, SCL-90-R = Symptom Checklist-90-Revised, SCL-90-R GSI = SCL-90-R General Severity Index, UxP+ = combat-unexposed cotwin of twin with PTSD, UxP− = combat-unexposed cotwin of twin without PTSD.