To evaluate the efficacy of choline alphoscerate on improving symptoms related to depression, anxiety, and subjective memory complaints compared to placebo in patients with Major Depressive Disorder(MDD) accompanied with subjective cognitive decline, who are over the age of 60.

This clinical trial will include the participants over age 60, diagnosed as MDD under treatment of antidepressant longer than 1 month's period, assessed as Hamilton Rating Scale for Depression(HAM-D) ≥ 14, and Mini-Mental State Examination(MMSE) ≥ 20, and those who are accompanied with subjective memory complaints. The investigators will evaluate the clinical efficacy of symptomatic improvement in depression, anxiety, and subjective memory complaints. The investigators will assess these outcomes including memory function, depression, anxiety, and satisfaction on medication with scales comparing control group with treatment group under 8 weeks of medication.

This is a multi-center, randomized, double-blind, placebo-controlled, Phase IV trial to evaluate the efficacy.

Participants in the treatment group will take the choline alfoscerate as adjunctive therapy with their own antidepressants. Participants in the control group will take the placebo, which would not affect their medical condition, for the adjunctive therapy is the choice of agreement between clinician and participants. If there is the necessity of change in antidepressant or of adjustment of their dosage, investigator can stop the clinical trial and proceed to another treatment.

Inclusion Criteria:

1. Age ≥ 60 years
2. Diagnosed as MDD under the criteria of Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and confirmed with MINI-Depression
3. HAM-D ≥ 14
4. MMSE ≥ 20
5. Who had continuous subjective memory complaints more than 6 months before the period of screening
6. Who had taking antidepressants longer than 1 month in the period of screening

Exclusion Criteria:

1. Diagnosed as schizophrenia, bipolar disorder, PTSD, OCD or other significant mental disorder under the criteria of DSM-5 (only the participants who had depressive disorder, sleep disorder, and the anxiety disorder are allowed to be included)
2. Who have medically unstable disease (only the participants, who have diabetes mellitus or hypertension under control with stable medication for 3 months could be included)
3. Diagnosed as dementia or mild cognitive impairment
4. Participants who are already taking choline alfoscerate within 6 months of period
5. Participants who have been taking medication of antipsychotics (including quetiapine), mood stabilizer, cognitive enhancer including donepezil, rivastigamine, galantamine, and memantine within 1months.
6. Participants who had previous history of liver disease or renal disease
7. Participants who had allergic reaction to choline alfoscerate
8. Other specific condition, which could be inappropriate for the trial inclusion, under the judgement of the principal investigator