Compounds for use in the treatment or prophylaxis of an affective disorder, which compound is represented by formula I in which the dotted line represents a single or a double bond; and R5 and R5' are independently -H, -OH or -OR6, where R6 is a linear or branched C1-C4 alkyl; X is -CH2O-; Z is -CH2??2O-,-CH(CH3)CH2O- or -CH2CH(CH3)O-; m is 1; and n is an integer of 1-5; or a pharmaceutically acceptable salt, prodrug, metabolite, or hydrate thereof.