A method for predicting options of depression treatment drugs includes (a) measuring a phosphoethanolamine (PEA) level in blood collected from a patient suspected of depression, (b) measuring whether the blood PEA level of the patient is lower than a reference value or not, wherein if the measured value of the patient is lower than values of healthy persons, the patient suffers from depression exhibiting a decreased PEA level as an indicator, and (c) predicting options of depression treatment drugs on the basis of the presence or absence of decreased blood PEA level in the patient. Thus, PEA, which is a biomarker of depression, can be directly linked to treatment.
