Table 1

Participant characteristics

CharacteristicEPO (n = 37)Placebo (n = 39)p value
Bipolar disorder/treatment-resistant depression, n17/2019/200.81
Age, yr, mean ± SD40 ± 1042 ± 120.47
Female, n26260.74
Education, yr, mean ± SD15 ± 415 ± 30.75
HDRS baseline score, mean ± SD15 ± 714 ± 80.83
Number of previous mood episodes, mean ± SD11 ± 117 ± 60.11
Illness duration, yr, mean ± SD18 ± 1120 ± 110.42
Concomitant medications, n
 Lithium11120.69
 Anticonvulsants22220.33
 Antidepressants21200.53
 Antipsychotics11100.88
 Benzodiazepines10100.40
 Melatonin660.44
 No medications220.96
No. of medications, mean ± SD2.3 ± 1.42.3 ± 1.20.98
Total hippocampal volume at baseline, mm3
 Left3560 ± 3713434 ± 3280.12
 Right3647 ± 3713601 ± 3810.60
Hippocampal Asymmetry Index, mean ± SD1.2 ± 2.02.3 ± 2.00.02
Total intracranial volume, mm3, mean ± SD1803663 ± 2943241706446 ± 1451700.08
Global cognition composite score, baseline, mean ± SD*−0.4 ± 0.8−0.2 ± 0.7
RAVLT total learning score, baseline, mean ± SD45 ± 1046 ± 9
RAVLT total learning score, follow-up, mean ± SD50 ± 947 ± 11
RAVLT change from weeks 1–9, mean ± SD5 ± 81 ± 60.03
  • EPO = erythropoietin; HDRS = Hamilton Depression Rating Scale; RAVLT = Rey Auditory Verbal Learning Test; SD = standard deviation.

  • * The cognitive composite score was calculated by summing the z-transformed scores from tests probing the different cognitive domains: RAVLT total recall trials I–V (verbal memory), Rapid Visual Processing speed for correct responses and Repeatable Battery for the Assessment of Neuropsychological Status coding (attention), Wechsler Adult Intelligence Scale letter-number sequencing, Trail Making Test B and verbal fluency letter D (executive function and working memory) as described in our original trial outcome paper.10