Table 3 Characteristics of studies: twin studies
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] Australia | 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). |