Association between social networking and dementia: A systematic review of observational studies

Poor social networking (SN) is associated with the development of cognitive impairment and dementia. Our objective was to perform a systematic review of the evidence on the associations between SN and the incidence of dementia, disease pathology, level of cognition, and brain structure. Bibliographic databases (PubMed, Embase, Cochrane Library, CINAHL) and additional sources (Open Gray, Google Scholar, manual searches) were screened through November 30, 2024. Observational studies assessing the SN-dementia link were selected, with data extraction and bias evaluation performed independently by two authors via the PRISMA checklist and Newcastle-Ottawa Scale. We included 17 observational studies (355 initially screened), involving 20,678 participants aged 40-90 years, published between 2000 and 2024. Studies have utilized various SN assessment tools and cognitive measures, including the MMSE and MoCA. Poor SN was consistently associated with increased risks of dementia, cognitive decline, and severe disease pathology, particularly Alzheimer's disease (AD). Larger and more integrated SNs were linked to better cognitive resilience and lower conversion rates from mild cognitive impairment (MCI) to dementia. One study on frontotemporal dementia (FTD) indicated that the SN might mitigate cortical atrophy. SN size and density are also correlated with favorable structural brain changes, such as greater gray matter volume. This review highlights SN as a modifiable factor in dementia risk. However, its role in non-AD dementia, particularly FTD, requires further investigation. Future research should include more culturally diverse and methodologically robust studies. Randomized controlled trials will be important to determine whether intervention to expand social networks decreases incidence of progression of dementia.