Table 3: Summary of studies on the effect of socialization on incident dementia.

StudyLength and frequencyProtocolSampleMMSE (baseline mean)Outcome measuresMajor findings

Wilson et al. [76]4 years; annual check upLongitudinal clinicopathological cohort study (i) Clinical diagnosis of AD
(ii) Change in measures of global cognition and specific cognitive functions
(i) Loneliness associated with cognitive decline and development of AD

Wang et al. [77]Data collection (9  years)Longitudinal population-based study 27.3(i) Frequency of social and leisure activities engaged 6.4 years before diagnosis
(ii) Baseline MMSE
(iii) MMSE of incident dementia cases
(i) Socially and mentally stimulating activity may preserve mental functioning in the elderly, reducing risk of dementia

Friedland et al. [78]Questionnaire data collection   
(i) Monthly involvement in possible 26 nonoccupational activities at early adulthood and middle adulthood(i) AD patients are less active in midlife than HC participants

Bennet et al. [79]6-7 yearsLongitudinal, epidemiological clinicopathological cohort study 25.8 (not used in analysis)(i) Annual clinical evaluation
(ii) Brain autopsy at death
(iii) Social network size (number of individuals seen at least once/month)
(i) Larger social network sizes observed in participants with higher level of cognition

Fratiglioni et al. [80]3 yearsLongitudinal community-based study >23(i) Social network at baseline, clinical evaluation at baseline and 3 years(i) Limited social network ties and interaction increased risk of developing dementia

: number of participants in healthy control group and group diagnosed with AD. MMSE: Mini-Mental State Examination.