Psychosocial and Cardiovascular Contributors to Longitudinal Cognitive Aging in Type 2 Diabetes
Creators: name: Kraal, Ann
Publisher: name: My University
Year: 2021
Subjects: subject: Hemoglobin A1c
subject: Memory
subject: Emotional Support
subject: Dementia
subject: Older Adults
subject: Psychology
subject: FOS: Psychology
subject: Social Sciences

description: Type 2 diabetes (T2D) confers substantial risk for dementia and accelerated cognitive decline in older adulthood. Glycemic control, indexed by hemoglobin A1c (HbA1c), is a marker of T2D severity, with higher levels of HbA1c reflecting poorer glycemic control. Poor glycemic control is associated with adverse cognitive outcomes in older adults with T2D, and chronically uncontrolled T2D may pose greater risk for dementia in comparison to controlled T2D. Although mechanisms underlying the association between T2D/HbA1c and cognition in older adulthood are underdeveloped, prior studies have implicated psychosocial factors, such as depressive symptoms, as well as cardiovascular factors, such as elevated homocysteine levels, in pathways linking T2D to cognitive decline and dementia. In comparison to risk pathways, relatively less is known regarding the role of potentially protective psychosocial factors such as emotional support. Consistent with the stress-buffering hypothesis, higher levels of support may buffer against T2D-related risk for poor cognitive function in older adults. The overarching goals across all three studies in this dissertation are two-fold: (1) to characterize the associations between markers of T2D severity (HbA1c and homocysteine) and cognitive outcomes, and (2) to test the role of emotional support as a potential buffer against T2D-related risk for cognitive morbidity. Specifically, Study 1 examined the role of depressive symptoms as a mediator of the association between HbA1c and cognition as well as the role of emotional support as a moderator of these associations in a sample of older adults with T2D. Study 2 examined the cross-sectional association between homocysteine and four domains of cognition as well as the moderating role of emotional support in homocysteine-cognition associations in older adults with uncontrolled T2D. Study 3 was a longitudinal extension of Studies 1 and 2 using data from a U.S.-wide sample of older adults with T2D. Study 3 examined the mediating role of four-year changes in depressive symptoms in the association between HbA1c and six-year memory decline as well as the role of emotional support as a cross-sectional and longitudinal moderator of associations. Findings from this dissertation suggest that for older adults with T2D, poor glycemic control may lead to increases in depressive symptoms and contribute to subsequent episodic memory decline. Furthermore, for older adults with uncontrolled T2D, higher levels of homocysteine may lead to lower performance in frontally mediated cognitive domains. Additionally, emotional support may represent an important psychosocial resource that can be targeted to reduce the impact of T2D-related risk for increases in depressive symptoms and poor memory. Emotional support may also reduce the adverse impact of depression on processing speed. Together, findings from this dissertation provide preliminary evidence for behavioral and biological mechanisms underlying T2D-related cognitive morbidity, and point to emotional support as a potentially protective factor against cognitive decline and dementia. Implications and future directions are discussed.