Sources of Individual Differences in Cognitive Functioning
Open Access
- Author:
- Roth, Amy E.
- Graduate Program:
- Human Development and Family Studies
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 26, 2005
- Committee Members:
- Steven Howard Zarit, Committee Chair/Co-Chair
Boo Johansson, Committee Member
Scott Hofer, Committee Member
Bonnie J Meyer, Committee Member
Michael J Rovine, Committee Member - Keywords:
- cognitive aging
- Abstract:
- The incidence and prevalence of many diseases associated with cognitive impairment (i.e. diabetes, cardiovascular disease) increase as individuals’ age. Cognitive declines due to diseases are not a part of the normal cognitive aging process. When examining correlates of normal cognitive aging, many researchers do not account for non-normative cognitive changes. The current study examined how diseases and psychosocial factors are associated with changes in cognition. Participants were part of the Health-70 study, a longitudinal assessment of two cohorts of Swedish older adults who underwent medical examinations and completed cognitive and psychosocial instruments at ages 70 (n=768), 75 (n=556) and 79 (n=483). Individuals who survived were also followed up at age 85. Using repeated measures analysis of variance with polynomial contrasts, the role of personality (neuroticism and extroversion) social support (marital status and contact with children), and subjective health were examined in explaining within and between-person differences in level and change on five cognitive tests (space, speed, digits forward, digits backwards, and verbal meaning). These associations were examined in participants who were assessed at ages 70, 75, ad 79, as well as in an exploratory analysis of a smaller sample of participants who were also followed up at age 85. In the 70-79 year-old sample, when accounting for death, diseases, medications, and demographic variables (gender, education, cohort), subjective health was significantly associated with linear decline on the space test [F(1, 194) = 4.19, p<.05; r2=.003], curvilinear decline on the speed test [F(1, 188) = 3.91, p<.05; r2=.02], and within-person differences [F(1, 265) = 3.84, p<.06; r2=.01] and liner decline [F(1, 265) = 7.06, p<.01; r2=.03] on the verbal meaning test. Neuroticism was significantly associated with curvilinear decline on the digits backwards test [F(1, 191) = 6.15, p<.05; r2=.01]. Extroversion was significantly associated with level of performance on the verbal meaning test [F(1, 265) = 8.09, p<.01; r2=.02]. Findings highlight the importance of both psychosocial and biomedical factors in explaining individual differences in cognitive aging.