This study is aiming to evaluate the efficacy and safety of Guilingji capsule in older adults with mild-to-moderate cognitive impairment who diagnosed as the kidney and marrow deficiency pattern in TCM. A total of 348 participants are evenly assigned to two arms. In the intervention arm, participants receive Guilingji capsule and Ginko Biloba Extract mimetic in combination, while the other arm will receive Ginko Biloba Extract tablet with Gulingji mimetic.

This study is a multi-center, randomized, positive control, noninferiority clinical trials. Experimental arm (174 cases) take 0.6 g of Gulingji capsules once a day and 19.2 mg of Ginko Biloba Extract mimetic three times a day. Active Comparator arm (174 cases) should take 0.6 g of Gulingji mimetic once a day and 19.2 mg of Ginko Biloba Extract tablet three times a day. The intervention lasted for 24 weeks. Clinical researchers, participants and statisticians are blinded to the treatment assignment throughout the study. Co-primary efficacy endpoints are change from baseline to week 12 and 24 in Mini-Mental State Examination score and Montreal Cognitive Assessment (MoCA) total score.Change from baseline to week 12 and 24 in Clinical Dementia Rating score, Alzheimer's Disease Assessment Scale-Cognitive subscale score, Activities of Daily Living, and Chinese Medicine Symptom Scale scoreare additional endpoints. Prespecified secondary biomarker endpoint is change from baseline in the serum level of acetylcholine and acetylcholinesterase at week 24.

Inclusion Criteria:

1. Aged between 60 and 85 years old
2. With a disease course ≥ 6 months and confirmed by others
3. Mini-Mental State Examination (MMSE) score between 10 and 26, or MMSE score >26 but Montreal Cognitive Assessment (MoCA) score<26
4. Meeting the diagnostic criteria of mild-to-moderate cognitive impairment
5. Meeting the diagnostic criteria of kidney deficiency pattern in Traditional Chinese medicine
6. Screening visit brain MRI and CT scan consistent with the diagnosis of mild-to-moderate cognitive impairment
7. Adequate visual and auditory abilities to perform all aspects of the cognitive and functional assessments
8. Received a primary and/or a higher education
9. Lives at home with appropriate caregiver capable of accompanying the subject on all clinic visits, or community dwelling with caregiver capable of accompanying the subject on all clinic visits and visiting with the subject approximately 5 times per week for the duration of the study
10. Signed and dated written informed consent. The subject's caregiver must also consent to participate in the study

Exclusion Criteria:

1. Significant neurological disease, other than AD MCI and VaD, that may affect cognition, such as the Parkinson's disease, the Huntington's disease, normal pressure hydrocephalus, brain tumors, progressive supra-nuclear palsy, epilepsy, chronic subdural hematoma and multiple sclerosis, history of severe head trauma with persistent neurological deficits or known abnormal brain structure
2. Thyroid disease, vitamin B12 or folic acid deficiency, severe anemia or malnutrition, serious heart, liver, lung, kidney and other organ diseases that may affect the cognitive function
3. Allergic to Ginkgo products
4. Use of any other medications with the potential to affect cognition
5. Current presence of a clinically important major psychiatric disorder or symptom
6. Alcohol addiction, or long-term use of antipsychotic drugs, or a history of severe head trauma
7. Cannot complete with cognitive function examines.

Participants are randomly and evenly assigned to 2 groups using block randomization.Random numbers are generated by the stratified random method using the SAS statistical software and assigned by an independent statistician at the Good Clinical Practice Institute of Xiyuan Hospital. Drugs are numerically labeled and sequenced according to the random numbers. The drug randomization is conducted by drug supplier. The patients are assigned to the intervention according to the sequence.

The clinicians, patients and statistician are blind to the patients' grouping assignment and intervention. Database is locked after all data is inputted. The grouping information will be revealed when statistical analyses are conducted. The researchers reveal the second blinding and write the study report finally. Unblinding is allowed only in emergency situation for the patients