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Importance: Lack of a US dementia surveillance system hinders efforts to support and address disparities among persons living with Alzheimer disease and related dementias (ADRD)., Objective: To review diagnosis and prescription drug code ADRD identification algorithms to develop and implement case definitions for national surveillance., Design, Setting, and Participants: In this cross-sectional study, a systematic literature review was conducted to identify unique International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) and prescription drug codes used by researchers to identify ADRD in administrative records. Code frequency of use, characteristics of beneficiaries identified by codes, and expert and author consensus around code definitions informed code placement into categories indicating highly likely, likely, and possible ADRD. These definitions were applied cross-sectionally to 2017 to 2019 Medicare fee-for-service (FFS) claims and Medicare Advantage (MA) encounter data to classify January 2019 Medicare enrollees. Data analysis was conducted from September 2022 to March 2024., Exposures: ICD-10-CM and national drug codes in FFS claims or MA encounters., Main Outcomes and Measures: The primary outcome was counts and rates of beneficiaries meeting each case definition. Category-specific age, sex, race and ethnicity, MA enrollment, dual-eligibility, long-term care utilization, mortality, and rural residence distributions, as well as frailty scores and FFS monthly expenditures were also analyzed. Beneficiary characteristics were compared across categories, and age-standardized to minimize confounding by age., Results: Of the 60 000 869 beneficiaries included (50 853 806 aged 65 years or older [84.8%]; 32 567 891 female [54.3%]; 5 555 571 Hispanic [9.3%]; 6 318 194 non-Hispanic Black [10.5%]; 44 384 980 non-Hispanic White [74.0%]), there were 4 312 496 (7.2%) with highly likely ADRD, 1 124 080 (1.9%) with likely ADRD, and 2 572 176 (4.3%) with possible ADRD, totaling more than 8.0 million with diagnostic evidence of at least possible ADRD. These beneficiaries were older, more frail, more likely to be female, more likely to be dual-eligible, more likely to use long-term care, and more likely to die in 2019 compared with beneficiaries with no evidence of ADRD. These differences became larger when moving from the possible ADRD group to the highly likely ADRD group. Mean (SD) FFS monthly spending was $2966 ($4921) among beneficiaries with highly likely ADRD compared with $936 ($2952) for beneficiaries with no evidence of ADRD. Differences persisted after age standardization., Conclusions and Relevance: This cross-sectional study of 2019 Medicare beneficiaries identified more than 5.4 million Medicare beneficiaries with evidence of at least likely ADRD in 2019 using the diagnostic case definition. Pending validation against clinical and other methods of ascertainment, this approach can be adopted provisionally for national surveillance.

Importance: Prior studies suggested that metformin may be associated with reduced dementia incidence, but associations may be confounded by disease severity and prescribing trends. Cessation of metformin therapy in people with diabetes typically occurs due to signs of kidney dysfunction but sometimes is due to less serious adverse effects associated with metformin., Objective: To investigate the association of terminating metformin treatment for reasons unrelated to kidney dysfunction with dementia incidence., Design, Setting, and Participants: This cohort study was conducted at Kaiser Permanente Northern California, a large integrated health care delivery system, among a cohort of metformin users born prior to 1955 without history of diagnosed kidney disease at metformin initiation. Dementia follow-up began with the implementation of electronic health records in 1996 and continued to 2020. Data were analyzed from November 2021 through September 2023., Exposures: A total of 12 220 early terminators, individuals who stopped metformin with normal estimated glomerular filtration rate (eGFR), were compared with routine metformin users, who had not yet terminated metformin treatment or had terminated (with or without restarting) after their first abnormal eGFR measurement. Early terminators were matched with routine users of the same age and gender who had diabetes for the same duration., Main Outcomes and Measures: The outcome of interest was all-cause incident dementia. Follow-up for early terminators and their matched routine users was started at age of termination for the early terminator. Survival models adjusted for sociodemographic characteristics and comorbidities at the time of metformin termination (or matched age). Mediation models with HbA1c level and insulin usage 1 and 5 years after termination tested whether changes in blood glucose or insulin usage explained associations between early termination of metformin and dementia incidence., Results: The final analytic sample consisted of 12 220 early terminators (5640 women [46.2%]; mean [SD] age at start of first metformin prescription, 59.4 [9.0] years) and 29 126 routine users (13 582 women [46.6%]; mean [SD] age at start of first metformin prescription, 61.1 [8.9] years). Early terminators had 1.21 times the hazard of dementia diagnosis compared with routine users (hazard ratio, 1.21; 95% CI, 1.12 to 1.30). In mediation analysis, contributions to this association by changes in HbA1c level or insulin use ranged from no contribution (0.00 years; 95% CI, -0.02 to 0.02 years) for insulin use at 5 years after termination to 0.07 years (95% CI, 0.02 to 0.13 years) for HbA1c level at 1 year after termination, suggesting that the association was largely independent of changes in HbA1c level and insulin usage., Conclusions and Relevance: In this study, terminating metformin treatment was associated with increased dementia incidence. This finding may have important implications for clinical treatment of adults with diabetes and provides additional evidence that metformin is associated with reduced dementia risk.

Importance: Hospice is an important end-of-life service for patients with Alzheimer disease and related dementias (ADRD)., Objective: To determine whether hospice use among patients with ADRD changed in association with recent policies aimed at reducing hospice misuse and long hospice stays, an outcome that may have disproportionately affected patients with ADRD because of their lengthy end-of-life trajectories., Design Setting and Participants: This observational cross-sectional study used Medicare hospice claims data from Medicare hospice episodes of care beginning between July 2008 and December 2019 among Medicare hospice beneficiaries 65 years or older at time of enrollment. Data analysis was conducted between September 2019 and June 2021., Exposures: The 2014 Improving Medicare Post-Acute Care Transformation (IMPACT) Act, which systematized audits of hospices with a high proportion of long stays, and the 2016 2-tier payment system, which reduced daily reimbursement rates after 60 days., Main Outcomes and Measures: Monthly percentage of (1) new patient enrollees, (2) patient census, and (3) care days provided to patients with an ADRD code., Results: The sample included 11 124 992 unique hospice episodes between 2008 and 2019; mean (SD) patient enrollment age ranged from 82.0 (8.2) years to 82.8 (8.7) years; the percentage of male patients ranged from 40.5% to 42.7%, and the percentage of Black, Hispanic, and White patients ranged from 7.7% to 8.2%, 1.5% to 2.0%, and 86.2% to 88.8%, respectively, across years. The percentage of new enrollees with an ADRD code dropped significantly during the months of IMPACT passage (-1.42 percentage points; 95% CI, -2.13 to -0.71) and implementation (-1.98 percentage points; 95% CI, -2.70 to -1.26) but rose again during the following months. While no significant changes were observed at the time of 2-tier payment implementation (0.15 percentage points; 95% CI, -0.21 to 0.51), the average rate of increase during the subsequent period was slower (0.01 percentage points per month; 95% CI, 0-0.02) than in earlier periods (0.05; 95% CI, 0.04-0.06 during the baseline period). Similar patterns were observed for the percentage of patient census and care days provided to patients with an ADRD code., Conclusions and Relevance: The results of this cross-sectional study of Medicare hospice claims data suggested that recent Medicare policies were associated with immediate and lasting reductions in the share of patients receiving hospice care with an ADRD code compared with expectations from preimplementation trends. Future research should examine mechanisms through which hospices enacted change and consequences for quality of care., Competing Interests: Conflict of Interest Disclosures: Dr Gianattasio reported grants from National Institute of Aging (NIA; 5R03AG061499-02) during the conduct of the study. Dr Moghtaderi reported grants from the NIA during the conduct of the study. Dr Lupu reported grants from George Washington University during the conduct of the study and research support George Washington University outside the submitted work, as well as a patent for copyright with royalties from Oxford University Press. Dr Prather reported grants from the National Institutes of Health during the conduct of the study. Dr Power reported grants from NIA during the conduct of the study and personal fees from Biogen and grants from DC Health outside the submitted work., (Copyright 2022 Gianattasio KZ et al. JAMA Health Forum.)

Importance: The implications of cigarette smoking and smoking cessation for hearing impairment remain unknown. Many studies on this topic have failed to account for attrition among smokers in their findings., Objective: To assess the association of cigarette smoking patterns with audiometric and speech-in-noise hearing measures among participants of the Atherosclerosis Risk in Communities Study., Design, Setting, and Participants: This cross-sectional study included participants of the Atherosclerosis Risk in Communities Study from 4 US communities. The analysis includes data from visit 1 (1987-1989) through visit 6 (2016-2017); data were analyzed from March 16 through June 25, 2021. Audiometric hearing and speech-in-noise testing was offered to all participants at visit 6. Participants with incomplete audiometric data or missing data for educational level, body mass index, drinking status, a diabetes or hypertension diagnosis, or occupational noise were excluded. In addition, individuals were excluded if they self-reported as having other than Black or White race and ethnicity, or if they self-reported as having Black race or ethnicity and lived in 2 predominantly White communities., Main Outcomes and Measures: Smoking behavior was classified from visit 1 (1987-1989) to visit 6 (2016-2017) using group-based trajectory modeling based on self-reported smoking status at each clinic visit. Hearing was assessed at visit 6. An audiometric 4-frequency (0.5, 1, 2, 4 kHz) pure-tone average (PTA) was calculated for the better-hearing ear and modeled as a continuous variable. Speech-in-noise perception was assessed via the Quick Speech-in-Noise Test (QuickSIN) and modeled continuously. Attrition during the 30 years of follow-up was addressed by inverse probability of attrition weighting., Results: A total of 3414 participants aged 72 to 94 years (median [IQR] age, 78.8 [76.0-82.9] years; 2032 [59.5%] women) when hearing was measured at visit 6 (2016-2017) were included in the cohort; 766 (22.4%) self-identified as Black and 2648 (77.6%) as White individuals. Study participants were classified into 3 smoking groups based on smoking behavior: never or former smoking at baseline (n = 2911 [85.3%]), quit smoking during the study period (n = 368 [10.8%]), and persistent smoking (n = 135 [4.0%]). In fully adjusted models, persistent smoking vs never or former smoking was associated with an average 2.69 (95% CI, 0.56-4.81) dB higher PTA (worse hearing) and 1.42 (95% CI, -2.29 to -0.56) lower QuickSIN score (worse performance). Associations were stronger when accounting for informative attrition during the study period (3.53 [95% CI, 1.14-5.93] dB higher PTA; 1.46 [95% CI, -2.52 to -0.41] lower QuickSIN scores). Smoking cessation during the study (vs never or former smoking) was not associated with changes in hearing., Conclusions and Relevance: In this cross-sectional study, persistent smoking was associated with worse audiometric hearing and speech-in-noise perception. Hearing measures among participants who quit smoking during the study period did not differ from those for never or former smokers, indicating that smoking cessation (as opposed to persistent smoking) may have benefits for hearing health.

Importance: In the US, dementia risk is higher in non-Hispanic Black individuals than in non-Hispanic White individuals. To evaluate progress toward reducing such disparities, tracking secular trends in racial disparities in dementia prevalence is essential., Objective: To examine whether relative racial disparities in dementia prevalence or incidence have changed in the US from 2000 to 2016., Design, Settings, and Participants: The Health and Retirement Study (HRS) is a nationally representative study of adults 50 years or older. New participants are recruited every 6 years, and study visits occur biennially. Approximately 17 000 to 22 000 respondents have been surveyed at each wave since 2000, achieving response rates of 81% to 89%. Data for this cohort study were obtained from non-Hispanic White and non-Hispanic Black participants aged 70 years and older from the 2000 to 2016 waves. For analyses of secular trends in racial disparities in dementia prevalence, each HRS wave was considered separately (range of participants meeting eligibility criteria in each wave, 6322-7579). For analyses of secular trends in racial disparities in dementia incidence, 7 subcohorts were created (range of participants meeting eligibility criteria in each subcohort, 5322-5961) following up people without dementia for 4 years from subcohort baseline visits in 2000, 2002, 2004, 2006, 2008, 2010, and 2012. Data were analyzed from October 2019 to August 2020., Exposures: Race based on self-response to closed-ended survey questions., Main Outcomes and Measures: Dementia status was determined using 3 algorithms with similar sensitivity and specificity across non-Hispanic White and Black participants. Disparities were characterized using ratio measures., Results: In this study, the mean age and percentage of male participants eligible for inclusion in analyses of racial disparities in dementia prevalence increased over time among non-Hispanic White participants (from 78.2 years and 40% in 2000 to 78.7 years and 44% in 2016) but remained steady in non-Hispanic Black participants during the same period (from 78.0 years and 37% in 2000 to 77.9 years and 38% in 2016). Prevalence ratios comparing Black and White participants ranged from approximately 1.5 to 1.9 across algorithms and years, whereas hazard ratios ranged from approximately 1.4 to 1.8. Although results suggest stable or declining dementia risk overall, there was no evidence suggesting change in relative racial disparities in dementia prevalence or incidence during follow-up., Conclusions and Relevance: This study did not find evidence to suggest that the ratio of dementia risk across Black and White individuals changed in the US between 2000 and 2016. Additional efforts to identify and mitigate the source of these disparities is warranted.

Importance: The association between late-life blood pressure (BP) and cognition may depend on the presence and chronicity of past hypertension. Late-life declines in blood pressure following prolonged hypertension may be associated with poor cognitive outcomes., Objective: To examine the association of midlife to late-life BP patterns with subsequent dementia, mild cognitive impairment, and cognitive decline., Design, Setting, and Participants: The Atherosclerosis Risk in Communities prospective population-based cohort study enrolled 4761 participants during midlife (visit 1, 1987-1989) and followed-up over 6 visits through 2016-2017 (visit 6). BP was examined over 24 years at 5 in-person visits between visits 1 and 5 (2011-2013). During visits 5 and 6, participants underwent detailed neurocognitive evaluation. The setting was 4 US communities: Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and Minneapolis, Minnesota. Follow-up ended on December 31, 2017., Exposures: Five groups based on longitudinal patterns of normotension, hypertension (>140/90 mm Hg), and hypotension (<90/60 mm Hg) at visits 1 to 5., Main Outcomes and Measures: Primary outcome was dementia onset after visit 5, based on Ascertain Dementia-8 informant questionnaires, Six-Item Screener telephone assessments, hospital discharge and death certificate codes, and the visit 6 neurocognitive evaluation. Secondary outcome was mild cognitive impairment at visit 6, based on the neurocognitive evaluation., Results: Among 4761 participants (2821 [59%] women; 979 [21%] black race; visit 5 mean [SD] age, 75 [5] years; visit 1 mean age range, 44-66 years; visit 5 mean age range, 66-90 years), there were 516 (11%) incident dementia cases between visits 5 and 6. The dementia incidence rate for participants with normotension in midlife (n = 833) and late life was 1.31 (95% CI, 1.00-1.72 per 100 person-years); for midlife normotension and late-life hypertension (n = 1559), 1.99 (95% CI, 1.69-2.32 per 100 person-years); for midlife and late-life hypertension (n = 1030), 2.83 (95% CI, 2.40-3.35 per 100 person-years); for midlife normotension and late-life hypotension (n = 927), 2.07 (95% CI, 1.68-2.54 per 100 person-years); and for midlife hypertension and late-life hypotension (n = 389), 4.26 (95% CI, 3.40-5.32 per 100 person-years). Participants in the midlife and late-life hypertension group (hazard ratio [HR], 1.49 [95% CI, 1.06-2.08]) and in the midlife hypertension and late-life hypotension group (HR, 1.62 [95% CI, 1.11-2.37]) had significantly increased risk of subsequent dementia compared with those who remained normotensive. Irrespective of late-life BP, sustained hypertension in midlife was associated with dementia risk (HR, 1.41 [95% CI, 1.17-1.71]). Compared with those who were normotensive in midlife and late life, only participants with midlife hypertension and late-life hypotension had higher risk of mild cognitive impairment (37 affected individuals (odds ratio, 1.65 [95% CI, 1.01-2.69]). There was no significant association of BP patterns with late-life cognitive change., Conclusions and Relevance: In this community-based cohort with long-term follow-up, sustained hypertension in midlife to late life and a pattern of midlife hypertension and late-life hypotension, compared with midlife and late-life normal BP, were associated with increased risk for subsequent dementia.

Importance: Brain atrophy and vascular lesions contribute to dementia and mild cognitive impairment (MCI) in clinical referral populations. Prospective evidence in older general populations is limited., Objective: To evaluate which magnetic resonance imaging (MRI) signs are independent risk factors for dementia and MCI., Design, Setting, and Participants: This population-based cohort study included 1553 participants sampled from the Atherosclerosis Risk in Communities Study who had brain MRI scans and were dementia free during visit 5 (June 2011 to September 2013). Participants' cognitive status was evaluated through visit 6 (June 2016 to December 2017)., Exposures: Brain regional volumes, microhemorrhages, white matter hyperintensity (WMH) volumes, and infarcts measured on 3-T MRI., Main Outcomes and Measures: Cognitive status (dementia, MCI, or nonimpaired cognition) was determined from in-person evaluations. Dementia among participants who missed visit 6 was identified via dementia surveillance and hospital discharge or death certificate codes. Cox proportional hazards models were used to evaluate the risk of dementia in 3 populations: dementia-free participants (N = 1553), participants with nonimpaired cognition (n = 1014), and participants with MCI (n = 539). Complementary log-log models were used for risk of MCI among participants with nonimpaired cognition who also attended visit 6 (n = 767). Models were adjusted for demographic variables, apolipoprotein E ε4 alleles, vascular risk factors, depressive symptoms, and heart failure., Results: Overall, 212 incident dementia cases were identified among 1553 participants (mean [SD] age at visit 5, 76 [5.2] years; 946 [60.9%] women; 436 [28.1%] African American) with a median (interquartile range) follow-up period of 4.9 (4.3-5.2) years. Significant risk factors of dementia included lower volumes in the Alzheimer disease (AD) signature region, including hippocampus, entorhinal cortex, and surrounding structures (hazard ratio [HR] per 1-SD decrease, 2.40; 95% CI, 1.89-3.04), lobar microhemorrhages (HR, 1.90; 95% CI, 1.30-2.77), higher volumes of WMH (HR per 1-SD increase, 1.44; 95% CI, 1.23-1.69), and lacunar infarcts (HR, 1.66; 95% CI, 1.20-2.31). The AD signature region volume was also consistently associated with both MCI and progression from MCI to dementia, while subcortical microhemorrhages and infarcts contributed less to the progression from MCI to dementia., Conclusions and Relevance: In this study, lower AD signature region volumes, brain microhemorrhages, higher WMH volumes, and infarcts were risk factors associated with dementia in older community-based residents. Vascular changes were more important in the development of MCI than in its progression to dementia, while AD-related signs were important in both stages.

Importance: Hypertension is a treatable potential cause of cognitive decline and dementia, but its greatest influence on cognition may occur in middle age., Objective: To evaluate the association between midlife (48-67 years of age) hypertension and the 20-year change in cognitive performance., Design, Setting, and Participants: The Atherosclerosis Risk in Communities cohort (1990-1992 through 2011-2013) underwent evaluation at field centers in Washington County, Maryland, Forsyth County, North Carolina, Jackson, Mississippi, and the Minneapolis, Minnesota, suburbs. Of 13 476 African American and white participants with baseline cognitive data, 58.0% of living participants completed the 20-year cognitive follow-up., Exposures: Hypertension, prehypertension, or normal blood pressure (BP) at visit 2 (1990-1992) constituted the primary exposure. Systolic BP at visit 2 or 5 (2011-2013) and indication for treatment at visit 2 based on the Eighth Joint National Committee (JNC-8) hypertension guidelines constituted the secondary exposures., Main Outcomes and Measures: Prespecified outcomes included the 20-year change in scores on the Delayed Word Recall Test, Digit Symbol Substitution Test, and Word Fluency Test and in global cognition., Results: During 20 years, baseline hypertension was associated with an additional decline of 0.056 global z score points (95% CI, -0.100 to -0.012) and prehypertension was associated nonsignificantly with 0.040 more global z score points of decline (95% CI, -0.085 to 0.005) compared with normal BP. Individuals with hypertension who used antihypertensives had less decline during the 20 years than untreated individuals with hypertension (-0.050 [95% CI, -0.003 to -0.097] vs -0.079 [95% CI, -0.156 to -0.002] global z score points). Having a JNC-8-specified indication for initiating antihypertensive treatment at baseline was associated with a greater 20-year decline (-0.044 [95% CI, -0.085 to -0.003] global z score points) than not having an indication. We observed effect modification by race for the continuous systolic BP analyses (P = .01), with each 20-mm Hg increment at baseline associated with an additional decline of 0.048 (95% CI, -0.074 to -0.022) points in global cognitive z score in whites but not in African Americans (decline, -0.020 [95% CI, -0.026 to 0.066] points). Systolic BP at the end of follow-up was not associated with the preceding 20 years of cognitive change in either group. Methods to account for bias owing to attrition strengthened the magnitude of some associations., Conclusions and Relevance: Midlife hypertension and elevated midlife but not late-life systolic BP was associated with more cognitive decline during the 20 years of the study. Greater decline is found with higher midlife BP in whites than in African Americans.