Defense Date


Document Type


Degree Name

Doctor of Philosophy


Pharmaceutical Sciences

First Advisor

Dr. Patricia Slattum

Second Advisor

Dr. Darcy Mays

Third Advisor

Dr. Pramit Nadpara

Fourth Advisor

Dr. River Pugsley

Fifth Advisor

Dr. Kristin Zimmerman


Introduction: Older adults have high prevalence of chronic illnesses that lead to have complex medication regimens. They are also more likely to have cognitive and functional impairments. Both cognitive/functional impairments and medication regimen complexity increase the risk of medication non-adherence. The objective of this study is to evaluate the association between prescription medication regimen complexity and cognitive/functional status at baseline and after two years, and to assess how changes in cognitive/functional status are associated with changes in medication regimen complexity.

Methods: This study used nationally representative sample of community-dwelling older adults from the Health and Retirement Study, followed over a two-year period. The exposures examined were cognitive status, and two types of functional status (Activities of Daily Living (ADLs) and Instrumental Activities of Daily Living (IADLs). The association between cognitive/functional status and medication regimen complexity was examined at baseline and after two years. Similar models were used to examine the relationship between cognitive/functional impairment and sub-components of complexity, and to assess how changes in cognitive/functional impairment were associated with changes in medication complexity over two years.

Results:Impairment in ADLs were associated with higher medication complexity at baseline (p=0.0029) and after two years (p=0.0243). Impairments in IADLs were associated with higher regimen complexity at baseline only (p=0.0130). Stratifying by depression status, IADL impairment was found to predict higher complexity at both time points, but only in participants without depression. Cognitive impairment was associated with lower medication regimen complexity at baseline (p

Conclusion: ADL impairment was strongly associated with higher medication complexity. IADL impairment showed some association with higher medication complexity, but this relationship may vary according to depression status and requires further investigation. Recognition of these impairments may offer health care providers the opportunity to intervene by re-assessing medication regimens for patients with functional impairments. Cognitive impairment was associated with lower medication complexity. Changes in cognitive or functional were not associated with changes in complexity. Further study is needed to investigate this relationship over a longer period of time.


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