The Effects of Social Isolation and Social Interaction on the Risk of Dementia Progression and Brain Function in SCD (Subjective Cognitive Decline, SCD)

Incidence of Mild Cognitive Impairment (MCI)

Incidence of Alzheimer's disease (AD)

Auditory Verbal Learning Test Huashan Version, AVLT-H The Auditory Verbal Learning Test-Huashan version (AVLT-H) assessment will be used as the primary outcome to assess EM for our study. The AVLT-H assesses several aspects of verbal EM through a list of 12 words, such as short or long-term delayed recall and recognition. It has been widely used as a semantic categorization memory test in mainland Chinese populations.

Montreal Cognitive Assessment, MoCA Overall cognitive function will be assessed using scores from the Montreal Cognitive Assessment Test (MOCA).

Wechsler Memory Scale-Revised Logical Memory, WMS-RLM Participants were asked to recall the stories they had heard after listening to a short story containing 25 information points, with 1 point for each information point and 25 points for each story, for a total of two stories out of 50 points, with higher scores indicating better short-term memory.

Wechsler Digit Span, WDS The scale is divided into two parts, forward numerical memory and inverse numerical memory, with 12 items each, with a maximum of 12 points and a maximum score of 24 points, with higher scores leading to better short-term memory and attention.

Verbal Fluency Test, VFT This scale is a measure of verbal fluency and requires the test subject to say as many names as possible in one minute, with only one repeat counted and the total number recorded.

Boston Naming Test, BNT This scale, one of the most commonly used methods for diagnosing naming disorder, consists of 30 black-and-white pictures of objects commonly used in daily life, and the test subjects are asked to name the pictures and record the total number of correct responses.

Lubben Social Network Scale-6, LSNS-6 The LSNS-6 could be a useful tool for assessing social networks among older mainland Chinese. In addition, suggestion is made to improve social networks, especially in family bonds and support, as a promising strategy in reducing late-life suicide risks in mainland China.

UCLA Loneliness Scale, University of California at Los Angels The 20-item UCLA Loneliness Scale (Version 3; UCLA-3) is a commonly used assessment of loneliness, with strong test-retest reliability as well as high internal consistency and validity (Cronbach's α of .89 to .94).

Geriatric Depression Scale, GDS Participants completed the short form of the Geriatric Depression Scale (GDS), a 15-item assessment to screen for depression in older adults, with higher scores indicating greater severity.

Pittsburgh sleep quality index, PSQI Self-reported sleep quality was assessed using the Pittsburgh Sleepiness Quality Index (PSQI).

Dual task consumption, DTC Dual-task cost (DTC) is the percentage change in walking speed between single-task and dual-task. It has been suggested that DTC predicts the risk of progression to dementia in older patients with MCI, with higher DTC and shorter time to progression to dementia and a higher risk.

fMRI

tau

Aβ

APOE genotyping Genotypes for rs7412 and rs429358, the single nucleotide polymorphisms (SNPs) defining the ϵ-2, ϵ-3 and ϵ-4 alleles of APOE, were genotyped using the commercially available TaqMan® SNP Genotyping Assay (ThermoFisher Scientific).

The online test is a connected test (Chinese revised version), and the test is divided into two parts, A and B, each of which includes exercises and tests. Before taking the test, the test taker should be asked to practice and then take the assessment. TMT-A requires the test subject to complete the connection from 1 to 25 as quickly as possible, in the order from smallest to largest, and the pen must not leave the paper during the connection. TMT-B requires the test subject to complete the connection from 1 to 25 as quickly as possible in the order of small to large, circle icon and square icon interval, and the pen must not leave the paper during the connection process. The time spent in each of the two parts is recorded.