The present invention is directed to methods and dosing regimens for the treatment of depression (preferably, treatment resistant depression), for the treatment of depression in a suicidal patient, and/or for the treatment and/or prevention of suicidality (e.g. suicidal ideations) comprising genotyping a patient to determine their Val66Met rs6265 polymorphism in BDNF and administering a ketamine, preferably esketamine, preferably intranasal esketamine, according to a dosing regimen matched to the patient's genotype.