Alzheimer's disease and related dementia diagnoses among American Indian and Alaska Native adults aged ≥45 years, Indian Health Service System, 2016–2020
The conclusions, findings, and opinions expressed by the authors contributing to this manuscript do not necessarily reflect the official position of the Indian Health Service or the Centers for Disease Control and Prevention.
Abstract
Background
Alzheimer's disease is the most common type of dementia and is responsible for up to 80% of dementia diagnoses and is the sixth leading cause of death in the United States. An estimated 38,000 American Indian/Alaska Native (AI/AN) people aged ≥65 years were living with Alzheimer's disease and related dementias (ADRD) in 2020, a number expected to double by 2030 and quadruple by 2050. Administrative healthcare data from the Indian Health Service (IHS) were used to estimate ADRD among AI/AN populations.
Methods
Administrative IHS healthcare data from federal fiscal years 2016 to 2020 from the IHS National Data Warehouse were used to calculate the count and rate per 100,000 AI/AN adults aged ≥45 years with at least one ADRD diagnosis code on their medical record.
Results
This study identified 12,877 AI/AN adults aged ≥45 years with an ADRD diagnosis code, with an overall rate of 514 per 100,000. Of those, 1856 people were aged 45–64. Females were 1.2 times (95% confidence interval: 1.1–1.2) more likely than males to have a medical visit with an ADRD diagnosis code.
Conclusions
Many AI/AN people with ADRD rely on IHS, tribal, and urban Indian health programs. The high burden of ADRD in AI/AN populations aged 45–64 utilizing IHS health services highlights the need for implementation of ADRD risk reduction strategies and assessment and diagnosis of ADRD in younger AI/AN populations. This study provides a baseline to assess future progress for efforts addressing ADRD in AI/AN communities.
Key points
- This is the first study to provide estimates of Alzheimer's disease and related dementias (ADRD) among American Indian/Alaska Native (AI/AN) populations who receive medical care at Indian Health Service, tribal, and urban programs or through Purchased/Referred Care.
- 12,877 AI/AN people aged 45 years or older had an ADRD diagnosis code in their medical record in fiscal years 2016 to 2020, with an overall rate of 514 per 100,000.
- 14% of people in our study with an ADRD diagnosis were in the 45- to 64-year age group (N = 1856), which suggests these populations may have high rates of early-onset dementia.
Why does this paper matter?
This study provides baseline data to assist Indian Health Service, CDC, and other public health and tribal partners in addressing ADRD in American Indian and Alaska Native communities. The findings emphasize the need for implementation of ADRD risk reduction strategies and the need to screen and diagnose ADRD in younger populations, and enhance clinical and community-based services to support AI/AN living with dementia and their caregivers.
INTRODUCTION
Alzheimer's disease and related dementias (ADRD) are characterized by a decline in one or more cognitive domains (complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition), leading to significant impairment in cognitive performance and eventually the ability to live independently.1 Dementia is a general term for an impaired ability to remember, think, or make decisions, which impacts daily life.2 Alzheimer's disease is the most common type of dementia and is responsible for up to 80% of ADRD diagnoses,3 and is the sixth leading cause of death in the United States.4
According to the 2020 Census, 2.9% of the US population (N = 9.7 million) identify as American Indian/Alaska Native (AI/AN) solely or in combination with another race.5 The observed prevalence of ADRD among AI/AN Medicare Fee-for-Service beneficiaries aged ≥65 years was 10.5% (N = 13,077) in 2014. Due to rapid aging in this population, this number is estimated to quadruple by 2030 (N = 65,000) and increase 10-fold by 2050 (N = 130,000).6 Although the greatest known risk factor for ADRD is age,3 some risk factors for ADRD disproportionately impact AI/AN individuals compared with people of other races and ethnicities,7, 8 such as diabetes, hypertension, obesity, hearing loss, traumatic brain injury, alcohol misuse, use of commercial tobacco products, depression, physical inactivity, social isolation, and air pollution.8-11
The Indian Health Service (IHS) is the federal agency within the U.S. Department of Health and Human Services that is tasked with providing healthcare and public health services to AI/AN individuals. IHS funding supports a comprehensive health service delivery system accountable for the health care for 2.6 million AI/AN people in 574 federally recognized tribes in 37 states. Most health care provided by IHS and tribal health programs occurs in rural and frontier areas. Healthcare services are provided directly through federally operated programs and facilities (I), tribally-owned and operated health programs (T), and urban Indian organizations (U), and are collectively referred to as I/T/U. Federal and tribal facilities are made up of 46 hospitals (24 federal and 22 tribally operated), 335 health centers (51 federal and 279 tribal), 103 health stations (24 federal and 79 tribal), 59 Alaska village clinics, 18 school health centers, and 12 youth regional treatment centers.12 In addition, 41 Urban Indian Organizations are funded to provide health programs for Urban AI/AN. When direct services are unavailable by I/T/U, care is purchased from non-IHS providers and facilities (known as Purchased/Referred Care or PRC). For this study, IHS services will refer to services provided directly through I/T/U programs and referrals using PRC.
There is limited information on the impact of ADRD among AI/AN people who use the IHS for their health care. The primary objective of this analysis was to estimate the burden of ADRD among AI/AN people who used IHS services.
METHODS
This study analyzed IHS National Data Warehouse (NDW) data for federal fiscal years (FY) 2016 to 2020 (October 1, 2015 to September 30, 2020), which includes information from inpatient, emergency department (ED), and outpatient visits from health care provided through IHS services.
An individual was defined as having ADRD if they had an International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code for an ADRD diagnosis (Table 1) in any one of up to 15 diagnosis variables on the individual's medical record.13 Data were selected for AI/AN persons aged 45 years or older from their first medical visit (i.e., inpatient, ED, or outpatient) with an ADRD diagnosis code during FY2016–2020. This count was used in the numerator to calculate ADRD diagnosis rates among AI/AN people aged ≥45 years who used IHS services. The aggregated annual IHS user population of AI/AN aged 45 years or older from 2016 to 2020 was used as the denominator. As described in earlier studies, the annual IHS user population includes all registered AI/AN people with at least one inpatient, ED, outpatient, or dental visit at an I/T/U provider or through PRC during the last three fiscal years.14 Rates were reported per 100,000 person-years.
| ICD-10-CM | Definition |
|---|---|
| F01 | Vascular dementia |
| F02 | Dementia in other diseases classified elsewhere |
| F03 | Unspecified dementia |
| F10.27 | Alcohol dependence with alcohol-induced persisting dementia |
| F10.97 | Alcohol use, unspecified with alcohol-induced persisting dementia |
| F13.27 | Sedative, hypnotic or anxiolytic dependence with sedative, hypnotic or anxiolytic-induced persisting dementia |
| F13.97 | Sedative, hypnotic or anxiolytic use, unspecified with sedative, hypnotic or anxiolytic-induced persisting dementia |
| F18.97 | Inhalant use, unspecified with inhalant-induced persisting dementia |
| F19.17 | Other psychoactive substance abuse with psychoactive substance-induced persisting dementia |
| F19.27 | Other psychoactive substance dependence with psychoactive substance-induced persisting dementia |
| F19.97 | Other psychoactive substance use, unspecified with psychoactive substance-induced persisting dementia |
| G30 | Alzheimer's disease |
| G31.01 | Pick's disease |
| G31.09 | Other frontotemporal dementia |
| G31.1 | Senile degeneration of brain, not elsewhere classified |
| G31.2 | Degeneration of nervous system due to alcohol |
| G31.83 | Dementia with Lewy bodies |
The count and rate were presented overall and by age group (45–64, 65–74, 75+ years), sex, care setting (inpatient, ED, outpatient), and region. Regions (Alaska, East, Northern Plains East, Northern Plains West, Southern Plains, Southwest, West) were created using the 12 geographic IHS Areas (Figure 1). Age, sex, region, and care setting are taken from the individual's first visit with an ADRD diagnosis code during 2016–2020. The West region did not include inpatient and ED visits because there are no I/T/U operated hospitals in that region and PRC data are incomplete for the region. As such, the rates in the West could be an undercount and were excluded in the comparison of regions.
Univariate Poisson regression was performed to calculate rate ratios (RRs), 95% confidence intervals (CIs), and associated p-values to compare the rates between age groups, sexes, and regions. Age- and sex-adjusted regional rates were calculated using the direct method and the projected 2000 US population.15 All analyses were conducted using SAS statistical software (version 9.4; SAS Institute Inc., Cary, NC); all tests were statistically significant if p < 0.05.
RESULTS
Table 2 shows that 12,877 AI/AN people had at least one ADRD diagnosis code (rate: 514 per 100,000). The rate of diagnosed ADRD was highest in those who were aged 75 years and older, which was 24.7 (95% CI: 23.5–26.0) times the rate in those aged 45–64 years. There were 11,021 AI/AN people aged ≥65 years with an ADRD diagnosis code; the rate of diagnosed ADRD (1384 per 100,000) was 12.7 (95% CI: 12.1–13.4) times higher than the rate for the 1856 AI/AN people aged 45–64 years (rate: 109 per 100,000). The rate of diagnosed ADRD for females (546 per 100,000) was 1.2 (95% CI: 1.1–1.2) times higher than the rate for males (475 per 100,000). Of the seven regions shown in Figure 1, Alaska and the East had the highest rates of diagnosed ADRD. Most AI/AN people with an ADRD diagnosis code were reported from the Southwest region (N = 4878); the Northern Plains East reported the lowest number (N = 592). Age- and sex-adjusted regional rates comparisons and significance were not different than the crude RRs (Supplementary Table 1). A patient's initial healthcare visit that included an ADRD diagnosis code in the medical record within fiscal years 2016–2020 occurred more frequently in an outpatient setting (N = 10,618), followed by inpatient setting (N = 1706) and ED (N = 553). The initial healthcare visit with the ADRD diagnosis during this time frame may not have been the initial diagnosis of ADRD for the patient.
| Counta | Denom.b | Rate | RR (95% CI) | |
|---|---|---|---|---|
| Total | 12,877 | 2,506,891 | 514 | |
| Age group | ||||
| 45–64 years | 1856 | 1,709,378 | 109 | Reference |
| 65–74 years | 2926 | 494,535 | 592 | 5.5 (5.1–5.8) |
| 75+ years | 8095 | 301,966 | 2681 | 24.7 (23.5–26.0) |
| Sex | ||||
| Male | 5400 | 1,137,304 | 475 | Reference |
| Female | 7476 | 1,368,449 | 546 | 1.2 (1.1–1.2) |
| Region | ||||
| Alaska | 1921 | 253,245 | 759 | 2.2 (2.0–2.4) |
| East | 707 | 88,033 | 803 | 2.3 (2.1–2.6) |
| Northern Plains East | 592 | 172,181 | 344 | Reference |
| Northern Plains West | 961 | 265,943 | 361 | 1.1 (1.0–1.2)c |
| Southern Plains | 2827 | 605,490 | 467 | 1.4 (1.2–1.5) |
| Southwest | 4878 | 804,686 | 606 | 1.8 (1.6–1.9) |
| Westd | 991 | 316,313 | 313 | Excluded |
| Care setting | ||||
| Inpatientd | 1706 | 2,189,578 | 78 | |
| EDd | 553 | 2,189,578 | 25 | |
| Outpatient | 10,618 | 2,506,891 | 424 | |
- Abbreviations: CI, confidence interval; ED, emergency department; RR, rate ratio.
- a Age group, sex, region, and care setting are taken from the individual's first visit with an International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code for Alzheimer's disease, dementia, or related-diseases on the record during fiscal years 2016–2020. A patient is counted once in the time frame 2016–2020 regardless of whether or not they had the diagnosis prior to 2016.
- b The Indian Health Service annual user population for fiscal years 2016–2020 is aggregated to create the denominator for the rate for all categories.
- c Rate ratio is not significant (p = 0.3412).
- d The West region is excluded from regional comparisons and from the inpatient and ED categories due to lack of I/T/U hospitals and incomplete Purchased and Referred care in the region.
Table 3 shows that for AI/AN people aged 45–64, the East had the highest rate of diagnosed ADRD, and Northern Plains East had the lowest rate. The East had the highest rate of diagnosed ADRD for those aged 65–74 years, and Alaska had the highest rate of diagnosed ADRD for those ≥75 years. For all regions, AI/AN people aged ≥75 had higher rates of diagnosed ADRD than younger age groups. Southwest and Northern Plains East had the largest RRs between ≥75 and 45–64 age groups (30.6 [95% CI: 28.0–33.4] and 29.8 [95% CI: 23.4–37.9] times more, respectively) versus 14.9 times more diagnosed ADRD (95% CI: 12.8–17.5) in Northern Plains West.
| Age group | Sex | |||||
|---|---|---|---|---|---|---|
| 45–64 years | 65–74 years | 75+ years | Male | Female | Total | |
| Age group | ||||||
| 45–64 years | 997 (125) | 858 (94) | 1856 (109) | |||
| 65–74 years | 1331 (608) | 1595 (579) | 2926 (592) | |||
| 75+ years | 3072 (2499) | 5023 (2806) | 8095 (2681) | |||
| Region | ||||||
| Alaska | 296 (171) | 479 (932) | 1146 (3987) | 868 (690) | 1053 (827) | 1921 (759) |
| East | 105 (175) | 211 (1227) | 391 (3630) | 293 (723) | 414 (872) | 707 (803) |
| Northern Plains East | 79 (67) | 132 (383) | 381 (1984) | 234 (293) | 358 (388) | 592 (344) |
| Northern Plains West | 234 (123) | 250 (511) | 477 (1830) | 460 (375) | 501 (349) | 961 (361) |
| Southern Plains | 403 (100) | 702 (559) | 1722 (2248) | 1150 (416) | 1677 (510) | 2827 (467) |
| Southwest | 594 (108) | 902 (594) | 3382 (3299) | 1995 (567) | 2883 (636) | 4878 (606) |
| Westc | 145 (68) | 250 (383) | 596 (1567) | 400 (285) | 590 (335) | 991 (313) |
| Total | 1856 (109) | 2926 (592) | 8095 (2681) | 5400 (475) | 7476 (546) | 12,877 (514) |
- a Age group, sex, and region are taken from the patient's first visit with an International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code for Alzheimer's disease, dementia, or related-diseases on the record during fiscal years 2016–2020. A patient is counted once in the time frame 2016–2020 regardless of whether or not they had the diagnosis prior to 2016.
- b The Indian Health Service annual user population for fiscal years 2016–2020 is aggregated to create the denominator for the rate for all categories.
- c The west region is excluded from regional comparisons and from the inpatient and emergency department categories due to lack of I/T/U hospitals and incomplete Purchased and Referred care in the region.
Females had a higher rate of diagnosed ADRD than males overall. However, males had a higher rate than females in the 45–64 years (125 vs 94 per 100,000; p < 0.001) age group. There was no difference in diagnosed ADRD between males and females among those 65–74 years (608 vs 579 per 100,000; p = 0.18). Females had a higher rate of diagnosed ADRD in those aged ≥75 years (2806 vs 2499 per 100,000; p < 0.001). Females in the East region had the highest rate of diagnosed ADRD among all females (872 per 100,000). Males in the East had the highest rate of diagnosed ADRD among all males (723 per 100,000). In every region (except Northern Plains West), females had a higher rate of diagnosed ADRD than males (all p-values <0.02).
DISCUSSION
This article presents novel insights about ADRD among AI/AN adults aged ≥45 years old who used IHS services. AI/AN people aged ≥65 had a significantly higher rate of diagnosed ADRD than those aged 45–64. However, 14% of people with an ADRD diagnosis code in this study were in the 45- to 64-year age group. This indicates that these populations may have high rates of early-onset dementia, given that globally 9% of all dementia cases are early onset.16 Healthcare providers should consider discussing ADRD risk reduction and assessing patients with reported memory concerns beginning in middle adulthood.
These results highlight the need for effective translation of ADRD research tailored to the needs of tribal communities17 and increased need for culturally appropriate training about ADRD for I/T/U clinicians.18 I/T/U clinicians are serving thousands of AI/AN people with ADRD and should have training in understanding ADRD across tribal cultures and how to communicate an ADRD diagnosis appropriately with AI/AN people. Tribal communities have unique cultures and relations to healthcare services, and approaches for other communities may not be effective or appropriate to use with all AI/AN people.16 The need for culturally appropriate training18 and healthcare services in the I/T/U programs will increase as the number of AI/AN individuals with ADRD is expected to rise.18 One Healthy People 2030 goal is to increase the number of people with memory concerns who have spoken to their provider.19 Culturally appropriate training and resources tailored to tribal communities can aid ADRD discussions between IHS providers and AI/AN patients when they bring up a memory concern.
The findings of this study also highlight the need for more healthcare provider outreach, education, and increased focus on the diagnosis of younger individuals who present with symptoms of cognitive impairment or dementia. In contrast to adults aged ≥65 years who can access Medicare services, adults living in non-Medicaid expansion states aged <65 years with cognitive impairment may rely on IHS services as their main form of healthcare delivery. Accessing Medicare may allow for more widely accessible services and care than may be available in IHS services, impacting younger AI/AN people with an ADRD diagnosis.
This study is subject to several limitations. ADRD burden among AI/AN individuals may be underestimated due to some I/T/U facilities possibly not reporting complete data to IHS NDW. Further, those who have an ADRD diagnosis through private insurance, Medicare or Medicaid, or another health system are not reflected in the IHS NDW unless they received care at an IHS facility. The study results represent the 2.6 million beneficiaries maintained within the IHS and may not be generalizable to the US AI/AN population (N = 9.7 million). Additionally, ADRD may not always be clinically recognized, particularly among older ages, as there is still an erroneous belief by some that ADRD is a normal part of aging. This may have resulted in an underestimate of the burden of ADRD in older adults.
Despite these limitations, this study is the first, to our knowledge, to provide estimates of the burden of ADRD for the IHS-funded healthcare system serving AI/AN people. This work provides the first baseline estimate of ADRD for IHS beneficiaries and indicates the burden of ADRD on AI/AN adults, their families, healthcare services, and communities. This baseline can demonstrate the impact of the new and significant efforts to address ADRD in tribal communities over time. IHS,20 CDC,21 and the Administration for Community Living (ACL)22 work nationally to address ADRD in AI/AN communities through direct service support, training, and public health infrastructure. These efforts include the Healthy Brain Initiative Road Map for Indian Country,18 IHS's Alzheimer's Grant Program, CDC's BOLD Program award to the Northwest Portland Area Indian Health Board, CDC's Healthy Brain Initiative B Award to the International Association for Indigenous Aging, and ACL's Alzheimer's Disease Program Initiatives Dementia Capability in Indian Country Awards. These awards address ADRD in AI/AN communities from different approaches, all working together to support AI/AN people living with ADRD and their caregivers.
CONCLUSION
As the number of AI/AN older adults continues to grow, efforts to increase the diagnosis of ADRD, especially at the early stages, and improve care and services for AI/AN people living with ADRD and their communities, will need to be enhanced to meet the demands. The optimal design of care and services to meet the needs of AI/AN people with dementia and their caregivers will come from and be anchored in the history, culture, and values of the sovereign tribes, nations, and urban communities in which they live. The results highlight the need to make sure that culturally relevant and appropriate clinical and community-based services to support AI/AN people living with ADRD and their caregivers are available.18, 20-22 Overall, this study is the first step in identifying ADRD burden, and it demonstrates the need for dementia risk reduction interventions that can delay or prevent later dementia for AI/AN people who use IHS services. These include risk factors for common comorbidities of diabetes and cardiovascular disease and the additional research needed to examine the extent that they can potentially reduce the prevalence of ADRD in AI/AN people.
AUTHOR CONTRIBUTIONS
Andria Apostolou: Study conceptualization; interpretation of data; preparation of the manuscript. Jordan L. Kennedy: Acquisition of data; analysis and interpretation of data; preparation of the manuscript. Marissa K. Person: Acquisition of data; analysis and interpretation of data; preparation of the manuscript. Eva M. J. Jackson: Interpretation of data; preparation of the manuscript. Bruce Finke: Study conceptualization; interpretation of data; preparation of the manuscript. Lisa C. McGuire: Study conceptualization; interpretation of data; preparation of the manuscript. Kevin A. Matthews: Study conceptualization; interpretation of data; preparation of the manuscript.
ACKNOWLEDGMENTS
The authors have nothing to report.
CONFLICT OF INTEREST STATEMENT
The authors have no conflicts of interests.
SPONSOR'S ROLE
None.
