IFNB1 and depressive symptom measurement: Whereas this observation failed to reach significance on a single trial level, pooled data from several clinical trials clearly showed that IFN-β increased the rate of depression from 8% in the placebo-treated group to 5–18% in patients treated with 22–44 μg IFN-β via different administration routes (p = 0.017) (Patten et al., 2005).