Secondary outcomes
Secondary measures include the MMSE, Montreal Cognitive Assessment (MoCA, Changsha version), CDR, Pittsburgh Sleep Quality Index (PSQI), and activities of daily living (ADL) scores, the gut microbiome, and serum markers.
The MMSE is an 11-question measure that tests five areas of cognitive function (orientation, registration, attention and calculation, recall, and language). The maximum score is 30, and a score below 24 is considered abnormal for dementia screening.
The MoCA (Changsha version) will also be used to evaluate general cognitive function, as it contains visuospatial processing and organizational capability parts and can make up for the shortcomings of the MMSE. The total score for the MoCA is 30, with a higher number indicating a more intact cognitive function. The MoCA has been shown to be a promising tool to detect MCI and early AD.
The CDR will be used as an assistant evaluation for patients’ dementia severity. It scores 0–3, with higher scores indicating more severity. It is a semi-structured interview performed with the patient and caregiver (informant), characterizing six domains of cognitive and functional performance. The CDR sum of boxes (CDR-SB), scored 0–18, will also be applied to assess patients’ cognitive status, with higher scores indicating worse functioning.
The PSQI will be used to assess participants’ comprehensive quality of sleep, which involves sleep quality, sleep duration, sleep efficiency, sleep disorders, daytime dysfunction, sleeping aids, etc. The total score for the PSQI is 21, with a higher score indicating a worse sleep quality.
ADL will be assessed including basic activities of daily living (BADL) and instrumental activities of daily living (IADL). An individual’s BADL will be evaluated mainly by the subjects’ performance from the perspectives of bathing, dressing, grooming, initiation, toileting, and feeding, with six items and a sum of scores ranging from 0 (normal) to 24 (complete dependence on others). A modified Lawton IADL scale will be used to measure the IADL of a subject, with eight items and a sum of scores ranging from 0 (normal) to 32 (complete dependence on others).
These clinical tests will be administered by a trained, certified clinician or rater experienced in the assessment of patients with cognitive deficits. The rater who conducts the CDR for a patient cannot complete any other rating scales for the same patient, and will be blinded to the results of all other neuropsychological scales. The previously described scales will be assessed at baseline (before the intervention), at 8 and 16 weeks (during the intervention), and at 6, 12, and 18 months after the intervention.
Blood samples will be collected from all participants to further assess the mechanisms of YZASG via changes in serum metabolic, inflammatory, and immunologic markers. All these tests will be entrusted to the laboratory medicine departments of Sichuan Academy of Medical Science & Sichuan Provincial People’s Hospital for conduction.
Fecal genomic DNA will be extracted from frozen stools using a QIAamp DNA Mini Stool Kit (Qiagen, Hiden, Germany), obtained from the patients with aMCI and 15–20 participants with normal cognition at baseline and at the end of the intervention. After polymerase chain reaction (PCR) amplification, DNA fragments will be sequenced on an Illumina HiSeq 2500 instrument and an Illumina HiSeq X instrument for 16S ribosomal DNA (16S rDNA) and metagenomics analyses (which will be chosen from some representative samples in the results of the 16S rDNA analysis), respectively, at Biomarker Technologies Co, Ltd. (Beijing, China) to analyze the differences in gut microbiome between patients with aMCI and individuals with normal cognition. When the results are available, the investigators will also assess the changes in gut microbiome between the treatment group and the placebo group after the intervention of YZASG in the same way.