Use of high cost care among Veterans with comorbid mental illness and Alzheimer's Disease and related dementias.



Alzheimer's Disease and Other Related Dementias (AD/ADRD) leads to frequent emergency department (ED) and inpatient use. Mental health symptoms among persons with AD/ADRD increases cognitive and functional disabilities and could contribute to these high rates of intensive health care use. The objective of this paper is to assess the relationship of mental illness on 12-month patterns in hospitalization and ED use among Veterans aged 65 and over with a new AD/ADRD diagnosis.


We used an existing dataset of administrative electronic health record data of Veterans with AD/ADRD from the US Veterans Health Administration linked with Medicare claims data from 2011-2015. We use multivariable logistic regression to examine the association between no pre-existing mental illness, pre-existing mental illness (e.g., major depressive disorder, generalized anxiety disorder, or post-traumatic stress disorder), and pre-existing severe mental illness-or SMI-(e.g., bipolar disorder, major depressive disorder with psychosis, or schizophrenia) and 12- month ED and hospitalization use and readmissions among Veterans who had an initial hospitalization visit. We estimated predicted probabilities, differential effect, and associated 95% confidence intervals.


In our sample, 1.4% had SMI and 11% had non-SMI mental illness. The unadjusted percentage with inpatient and ED use was higher among Veterans with SMI (34% and 26%, respectively) and Veterans with non-SMI mental illness (20%, 16%) compared with Veterans without pre-existing mental illness (12%, 9%). Compared to individuals with no pre-existing mental illness, having a pre-existing mental illness (1.27 percentage points, 95% CI: 0.76, 1.78) and a pre-existing SMI (7.17 percentage points, 95% CI: 5.66, 8.69) were both associated with an increased likelihood of ED use. The same pattern was observed for any inpatient use (mental illness 2.18, 95% CI: 1.59, 2.77; SMI 9.91, 95% CI: 8.21, 11.61). Only pre-existing SMI was associated higher hospitalization readmission.


Pre-existing mental illness increases use of high cost, intensive health care and this association is higher of more severe mental health conditions. We also show that pre-existing mental illness exerts a unique influence, above and beyond other comorbidities, such as diabetes, on ED and inpatient visits. More needs to be done to increase recognition of the unique risks of this combination of health conditions and encourage strategies to address them. Developing, testing, and implementing comprehensive strategies that address the intersection of ADRD and mental illness is promising approach that requires more focused attention.





Published Version (Please cite this version)


Publication Info

Shepherd-Banigan, Megan, Katherine EM Miller, S Nicole Hastings, Loren J Schleiden and Joshua M Thorpe (2023). Use of high cost care among Veterans with comorbid mental illness and Alzheimer's Disease and related dementias. PloS one, 18(5). p. e0282071. 10.1371/journal.pone.0282071 Retrieved from

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Megan E Shepherd-Banigan

Assistant Professor in Population Health Sciences

Dr. Megan Shepherd-Banigan designs research studies to improve the health, emotional well-being, and social functioning of adults with mental and physical disabilities. Her methods combine empirical approaches that address methodologically challenging research questions in health systems and policy research. Dr. Shepherd-Banigan uses large survey and administrative datasets to evaluate the impact of policies that support family members to care for adults with disabilities.  

Dr. Shepherd-Banigan won a VA Career Development Award from 2019-2024 and is studying ways to strengthen family support for veterans under-going traumatic stress treatment. She also leads a project that surveys family caregivers of Vietnam-era veterans who might be eligible for expanded support services under the VA Mission Act to evaluate program impacts. As co-investigator on an NIA-funded CARE IDEAS study (Terri Wetle, PI) , she is investigating end-of-life-care planning and well-being among dementia care dyads.  Finally, Dr. Shepherd-Banigan is leading a project in partnership with the Rosalynn Carter Institute for Caregivers to identify creative empirically-based approaches to support family caregivers. 


Susan Nicole Hastings

Professor of Medicine

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