Table 2.
Demographic, clinical, cognitive, and neurophysiological characteristics of participants by response subgroup. Mean ± standard deviation is reported throughout unless stated otherwise. Response subgroup comparisons were performed using an independent two-tailed t-test (continuous variables), Mann-Whitney U test (non-normally distributed continuous variables), or Fisher’s exact test (categorical variables). MADRS = Montgomery-Asberg Depression Rating Scale, % MSO = % of maximum stimulator output, MEP = motor evoked potential, SI1mV = 1mV stimulator intensity, CV = coefficient of variation, PAS = paired associative stimulation, SICI = short-interval intracortical inhibition, ICF = intracortical facilitation.
| Responders (n = 30) | Non-Responders (n = 46) | Statistics | |
|---|---|---|---|
| Demographics | |||
| Age (years) [range] | 66.2 ± 5.5 [57 – 86] | 66.9 ± 7.3 [53 – 92] | t74 = 0.43, p = 0.67 |
| % Female | 70.0 (n = 21) | 60.9 (n = 28) | p = 0.47 |
| % Caucasian | 93.3 (n = 28) | 95.7 (n = 44) | p = 0.73 |
| Years of education | 14.6 ± 2.2 | 14.6 ± 3.3 | t73 = 0.01, p = 0.99 |
| Clinical Measures | |||
| Baseline MADRS score | 24.2 ± 4.7 | 26.7 ± 5.7 | t74 = 2.03, p = 0.05 |
| Age of onset (years) [range] | 40.2 ± 17.3 [11 – 69] | 42.9 ± 18.3 [12 – 91] | t74 = 0.63, p = 0.53 |
| Duration of current depressive episode, median [range] | 46 [2 – 2100] weeks | 78 [8 – 1248] weeks | t74 = 1.45, p = 0.15 |
| % Non-response to ≥1 prior adequate antidepressant trial | 60.0 (n = 18) | 82.6 (n = 38) | p = 0.04 |
| % Concurrent anxiolytic / sedative use | 20.0 (n = 6) | 32.6 (n = 15) | p = 0.30 |
| % Comorbid anxiety disorder | 30.0 (n = 9) | 34.8 (n = 16) | p = 0.80 |
| Brief Symptom Inventory – Anxiety | 1.67 ± 0.90 | 1.59 ± 0.98 | t74 = 0.39, p = 0.69 |
| Medical comorbidity (CIRS-G total score) | 6.4 ± 4.0 | 6.5 ± 3.2 | t74 = 0.09, p = 0.92 |
| Reduced sleep (MADRS item 4 score) | 2.63 ± 1.47 | 2.83 ± 1.80 | t74 = 0.49, p = 0.63 |
| Pessimistic thoughts (MADRS item 9 score) | 2.63 ± 0.96 | 2.78 ± 1.07 | t74 = 0.62, p = 0.54 |
| Executive function score | 4.4 ± 1.6 | 4.4 ± 2.3 | t60 = 0.11, p = 0.91 |
| Delayed recall score (% retained) | 71.1 ± 29.4 | 73.6 ± 21.5 | t62 = 0.40, p = 0.69 |
| Week 12 venlafaxine dosage (mg/day) | 221.3 ± 79.0 | 266.6 ± 63.8 | W = 894, p = 0.01 |
| Neurophysiological Measures | |||
| Cortical Excitability | |||
| Resting motor threshold | 49.1 ± 9.2 % MSO | 48.5 ± 9.8 % MSO | t74 = 0.26, p = 0.79 |
| SI1mV | 62.7 ± 12.8 % MSO | 63.1 ± 16.7 % MSO | t74 = 0.12, p = 0.90 |
| CV of MEP amplitudes | 59.0 ± 19.5 % | 70.0 ± 24.7 % | t73 = 2.03, p = 0.05 |
| Cortical Inhibition & Facilitation | |||
| SICI Ratio | 0.58 ±0.38 | 0.68 ± 0.53 | t73 = 0.60, p = 0.55 |
| ICF Ratio | 1.83 ± 0.77 | 1.84 ± 0.87 | t73 = 0.25, p = 0.80 |
| Cortical silent period | 127.4 ± 34.5 ms | 123.2 ± 34.5 ms | t72 = 0.50, p = 0.62 |
| Cortical Plasticity | |||
| Average PAS Ratio | 1.09 ± 0.44 | 1.20 ± 0.57 | t58 = 0.64, p = 0.52 |
| Maximum PAS Ratio | 1.49 ± 0.67 | 1.64 ± 0.91 | t58 = 0.52, p = 0.61 |