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Table 3 Characteristics of studies: twin studies

From: The impact of social activities, social networks, social support and social relationships on the cognitive functioning of healthy older adults: a systematic review

Twin studies examining the impact of social relationships on cognitive function
Study Participants Design Social Activity Defined /Measure Cognitive Outcome Measures Results
Lee (2014) [84]
N = 119 pairs of MZ twins
Age: 65+
M Age = 71
Discordant MZ twin design Social activity: frequency of engagement in social activities incl. Contact family member, neighbour, friends; talk to neighbour; group activities; church activities; and voluntary work.
Adapted from the San Diego Successful Ageing Questionnaire.
Memory (composite of Logical Memory Story A, RAVLT, BVRT)
Processing speed (composite of TMT-A, Digit Symbol Coding)
Verbal fluency (composite of COWAT, Boston Naming Test)
Executive function (composite of Digit Span Backward, TMT-B/A, Stroop)
Cognitive function (composite of four cognitive domain scores)
Statistically significant association (controls included) between discordance scores for social activity and memory (p = 0.007).
No other associations found for social activity.
McGue (2007) [82]
Denmark (LSADT)
N = 70 pairs MZ twins
M Age = 77.4
M Age = 75.7
Discordant MZ twin design Social activity: engaging with others (leaving house, party) or mental activity (engaging in a hobby).
The Social Activity scale: frequency engaged with others and mental pursuits.
Cognitive Function (MMSE, composite measure) Social activity significantly correlated with initial level of cognitive functioning (r = 0.21 for MMSE, 0.44 for cognitive composite score). Social activity was moderately heritable (r = 0.36) Significant association between discordance scores and cognitive composite score (p < 0.001) but not MMSE (p > 0.25).
  1. MZ monozygotic, RAVLT Rey Auditory Verbal Learning Test, BVRT Benson Visual Retention Test, TMT-A Trail Making Test-A, COWAT Controlled Oral Word Association Test, TMT-B/A ratio score of Trail Making Test B/Trail Making Test A, LSADT Longitudinal Study of Ageing Danish Twins, MMSE Mini Mental Status Examination