Study to Explore the Optimal Dosage/Administration in Alzheimer's Disease

1. Period of study -48 months from the date of KFDA approval of the protocol 2. Study subjects -Patients with mild to moderate Alzheimer's disease 3. Study objectives 1. Primary objective * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on cognitive effect assessed by ADAS-cog at Week 12 post-dose 2. Secondary objectives * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on cognitive effect assessed by ADAS-cog at Week 8 post-dose * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on overall functional effect assessed by CDR at Weeks 8 and 12 post-dose * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on activities of daily living assessed by K-IADL at Weeks 8 and 12 post-dose * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on behavioral changes assessed by NPI at Weeks 8 and 12 post-dose * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on cognitive effect assessed by K-MMSE at Weeks 8 and 12 post-dose * To compare the efficacy of 2 doses of PM012 Tablet and placebo based on improvement on VAS assessed by Senile Dementia Pattern Identification Diagnosis System at Weeks 8 and 12 post-dose 4. Study drug / Comparator -650-mg PM012 Tablet by PuriMED Co., Ltd. / Placebo 5. Dosage/ Administration and Method of administration 1. Placebo group * Morning:Placebo 2T, Evening:Placebo 2T 2. Dose group 1 * Morning:Placebo 1T+Study drug 1T, Evening:Placebo 1T+Study drug 1T 3. Dose group 2 * Morning:Study drug 2T, Evening:Study drug 2T 4. Study drug is 650-mg PM012 tablet 5. The drug will be taken with water within 30 minutes after breakfast and supper. 6. Even if no meal is taken, dosing will not be omitted and the drug should be taken with enough amount of water. 6. Treatment duration -12 weeks 7. Number of subjects 1. placebo group * Efficacy population:42, Drop-out(20%)included:53 2. Dose group 1 * Efficacy population:42, Drop-out(20%)included:53 3. Dose group 2 * Efficacy population:42, Drop-out(20%)included:53 4. Total * Efficacy population:126, Drop-out(20%)included:159 8. Study method * This study is designed to be a multicenter, randomized, double-blind, parallel placebo group and 2 dose groups, phase 2 clinical study in patients with dementia of Alzheimer's type aged ≥ 50 and ≤ 85 years. * Once a subject voluntarily provides the written consent to participate in the study, he/she will be randomized only if meeting the inclusion criteria and exclusion criteria through screening test. Randomized subjects will receive the study drug or the placebo for 12 weeks.