SLC6A4 and depressive symptom measurement: Two out of four of the antidepressants that MADRS is based on, clomipramine and amitriptyline, share 5-HTT inhibition as part of their mechanism of action (Lundberg et al., 2012), which adds to the validity of the correlation between reduction of 5-HT1B receptor binding and MADRS after escitalopram for depression.