Table 1.
Demographics, structural and radiochemical variables, and clinical information of the study samples
| HCs (N = 40) | MDDs (N = 47) | p value (HCs vs. MDDs two-tailed t test) | |
|---|---|---|---|
| Age (years) | 38.0 ± 15.4 | 39.1 ± 12.1 | 0.70 |
| HRSD (17 item) | 0.8 ± 1.1 | 15.8 ± 7.1 | < 0.001 |
| BDI | 1.5 ± 2.1 | 23.2 ± 12.6 | < 0.001 |
| Years of education | 16.3 ± 2.7 | 14.5 ± 2.9 | < 0.001 |
| Age at onset | N/A | 23.6 ± 12.5 | |
| Number of previous depressive episodes | N/A | 6.5 ± 15.8 | |
| Median: 3 | |||
| Range: 0–99 | |||
| Length of current major depressive episode (weeks) | N/A | 57.8 ± 92.5 | |
| Median: 32 | |||
| Range: 3–584 | |||
| Weight (kg) | 74.9 ± 19.7 | 74.8 ± 18.9 | 0.99 |
| TGMV (cm3) | 643.2 ± 70.5 | 628.3 ± 62.6 | 0.30 |
| Injected dose (MBq) | 301.9 ± 131.8 | 293.2 ± 132.8 | 0.76 |
| Specific activity (MBq/nmol) | 54.4 ± 26.7 | 71.7 ± 42.0 | 0.03 |
| Injected mass (μg) | 3.1 ± 2.1 | 2.1 ± 1.2 | 0.01 |
| Day of the year of PET scan | 168 ± 111 | 205±110 | 0.13 |
| Time of the day of PET scan (hours past midnight) | 13.3 ± 1.2 | 14.3 ± 2.3 | 0.01 |
| Categorical variables | N (%) | N (%) | p value (HCs vs. MDDs, Fisher’s exact) |
| Female | 19 (48) | 30 (64) | 0.20 |
| Prior exposure to anti-depressants | N/A | 22 (47) | |
| Past substance abuse | N/A | 13 (36) | |
| Comorbid anxiety disorder | N/A | 21 (45) | |
| Comorbid dysthymia | N/A | 6 (13) | |
| Race/ethnicity | |||
| Asian | 6 (15) | 2 (4) | |
| African American | 4 (10) | 6 (13) | |
| Caucasian | 22 (55) | 27 (57) | |
| Hispanic | 8 (20) | 14 (30) | |
| > 1 Race | 0 (0) | 2 (4) |
HRSD: Hamilton rating scale for depression; BDI: Beck depression inventory