Vortioxetine for use in a method of treating a psychiatric disorder in a patient in combination with a monoamine oxidase inhibitor (MAOI), the method comprising: (a) administering vortioxetine; then (b) stopping the administration of vortioxetine; and (c) administering the first dose of a MAOI more than 24 days after step (b); wherein the psychiatric disorder is selected from the group consisting of depression, major depressive disorder, pre-menstrual dysphoric disorder, acute depressive episodes with bipolar I, treatment resistant depression, general anxiety disorder, obsessive compulsive disorder, panic disorder, post-traumatic stress disorder, social anxiety disorder, bulimia nervosa, cognitive dysfunction in pre-menstrual dysphoric disorder, attention deficit hyperactivity disorder, attention deficit hyperactivity disorder in adult patients, and combinations thereof; and wherein said patient is obese and has at least one of the following characteristics: i) a BMI of at least 35; ii) a %IBW of at least 150%; iii) a waist size greater than 106.68 cm (42 inches); iv) a % body fat greater than 40%; v) a % android body fat greater than 40%; vi) a % gynoid body fat greater than 40%; and vii) a total body fat greater than 40 kg. (a) administering vortioxetine; then (b) stopping the administration of vortioxetine; and (c) administering the first dose of a MAOI more than 24 days after step (b); wherein the psychiatric disorder is selected from the group consisting of depression, major depressive disorder, pre-menstrual dysphoric disorder, acute depressive episodes with bipolar I, treatment resistant depression, general anxiety disorder, obsessive compulsive disorder, panic disorder, post-traumatic stress disorder, social anxiety disorder, bulimia nervosa, cognitive dysfunction in pre-menstrual dysphoric disorder, attention deficit hyperactivity disorder, attention deficit hyperactivity disorder in adult patients, and combinations thereof; and wherein said patient is obese and has at least one of the following characteristics: i) a BMI of at least 35; ii) a %IBW of at least 150%; iii) a waist size greater than 106.68 cm (42 inches); iv) a % body fat greater than 40%; v) a % android body fat greater than 40%; vi) a % gynoid body fat greater than 40%; and vii) a total body fat greater than 40 kg. wherein the psychiatric disorder is selected from the group consisting of depression, major depressive disorder, pre-menstrual dysphoric disorder, acute depressive episodes with bipolar I, treatment resistant depression, general anxiety disorder, obsessive compulsive disorder, panic disorder, post-traumatic stress disorder, social anxiety disorder, bulimia nervosa, cognitive dysfunction in pre-menstrual dysphoric disorder, attention deficit hyperactivity disorder, attention deficit hyperactivity disorder in adult patients, and combinations thereof; and wherein said patient is obese and has at least one of the following characteristics: i) a BMI of at least 35; ii) a %IBW of at least 150%; iii) a waist size greater than 106.68 cm (42 inches); iv) a % body fat greater than 40%; v) a % android body fat greater than 40%; vi) a % gynoid body fat greater than 40%; and vii) a total body fat greater than 40 kg. i) a BMI of at least 35; ii) a %IBW of at least 150%; iii) a waist size greater than 106.68 cm (42 inches); iv) a % body fat greater than 40%; v) a % android body fat greater than 40%; vi) a % gynoid body fat greater than 40%; and vii) a total body fat greater than 40 kg.