Supplementary Material for: Informant-Reported Cognitive Decline and Activity Engagement across Four Years in a Community Sample

<p><b><i>Background:</i></b> Subtle age-related cognitive decline may be associated with the capacity to remain engaged in mental, physical, and social activities. Informant reports of cognitive decline potentially provide additional information to psychometric tests on change in everyday cognitive function relevant to activity engagement. <b><i>Objective:</i></b> To investigate relations between decline in everyday cognitive function as assessed by informant report and activity engagement in community-dwelling older adults. <b><i>Methods:</i></b> A sample of cognitively normal older adults was drawn from the 2 latest waves of the PATH Through Life Study (<i>n</i> = 1,391; mean age 74.5 ± 1.5, 48.4% female). PATH is a 16-year longitudinal cohort study set in the Canberra/Queanbeyan district, Australia. Assessments were carried out at baseline, and at 3 subsequent time-points 4 years apart. At wave-4, the IQCODE, an informant measure of 4-year cognitive decline was provided by a spouse, family member, or friend of each participant. Activity engagement was assessed by the abbreviated RIASEC Mental Activity List, self-reported frequency and duration of physical activity (Whitehall Questionnaire) and the Lubben Social Network Scale that assessed interaction with family/friends. Participants provided demographic information, self-reported health status (SF-12), and responses to the Goldberg Depression Scale. The Symbol Digit Modalities Test (SDMT) and California Verbal Learning Test (CVLT) were used to measure objective 4-year cognitive change. Those with MMSE score of ≤27 were excluded. <b><i>Results:</i></b> IQCODE score predicted disengagement from mental activities over 4 years in cognitively healthy adults (β = -0.056, standard error [SE] = 0.019, <i>p</i> = 0.004). This association was robust to covariate control and change on the SDMT which was also significantly related to mental activity disengagement. In models adjusted for change scores on the SDMT and the CVLT, the IQCODE was associated with less physical (β = -0.692, SE = 0.24, <i>p</i> = 0.004) and social engagement (β -0.046, SE = 0.021, <i>p</i> = 0.032), but relationships were attenuated with the inclusion of covariates. <b><i>Conclusion:</i></b> Informant-reported cognitive decline in a non-clinical sample was linked to activities that support cognitive health. Associations were robust to adjustment for cognitive change scores. Utilising informant reports prior to the manifestation of clinically relevant decline may identify those who would benefit most from personalised activity interventions.</p>