Medicare billing records report being told of the diagnosis.242-246 Because Alzheimer’s dementia is often underdiagnosed — and if it is diagnosed by a clinician, people are often unaware of their diagnosis — a large portion of Americans with Alzheimer’s may not know they have it. For more detailed information about detection of Alzheimer’s and other dementias in the primary care setting, see the Special Report from 2019 Alzheimer's Disease Facts and Figures. 247 Ultimately, future estimates of the prevalence of Alzheimer’s dementia, as defined by the presence of pathologic biomarkers, will be lower than the estimated prevalence based on clinical symptoms (the currently reported 6.5 million). For example, if we were to assume that 30% fewer individuals with the clinical symptoms of Alzheimer’s dementia lack the presence of defining biomarkers, in 2022, this would translate to roughly 4.5 million Americans age 65 and older being classified as having Alzheimer’s dementia. By contrast, the prevalence of Alzheimer’s disease will be higher because it will include those with MCI due to Alzheimer’s disease. Using 2022 again as an example, combining the roughly 4.5 million Americans age 65 and older with Alzheimer’s dementia and the estimated 5 million Americans age 65 or older with MCI due to Alzheimer’s disease, there would be 9.5 million Americans with Alzheimer’s disease. It should be noted that both symptom-based prevalence estimates of Alzheimer’s dementia and biomarker-based prevalence estimates of Alzheimer’s disease will increase in the future due to growth in the proportion of Americans age 65 and over, the population most at risk. When a conclusive connection is shown between biomarkers and the preclinical stage and when epidemiological studies include biomarker-based diagnoses, an Alzheimer’s disease prevalence estimate that includes individuals throughout the continuum of Alzheimer’s disease will be even higher, as it will incorporate those with biomarker-confirmed Alzheimer’s dementia, those with biomarker-confirmed MCI due to Alzheimer’s disease and those with preclinical Alzheimer’s disease. 22 Alzheimer’s Association. 2022 Alzheimer’s Disease Facts and Figures. Alzheimers 33.3% Projected Increases Between 2020 and 2025 in Alzheimer’s Dementia Prevalence by State Prevalence figure 3 Prevalence of Subjective Cognitive Decline The experience of worsening or more frequent confusion or memory loss (often referred to as subjective cognitive decline) is one of the earliest warning signs of Alzheimer’s disease and may be a way to identify people who are at high risk of developing Alzheimer’s or other dementias as well as MCI.248-252 Subjective cognitive decline refers to self-perceived worsening of memory and other thinking abilities by an individual, separate from cognitive testing, a physician’s diagnosis or anyone else noticing. Not all those who experience subjective cognitive decline go on to develop MCI or dementia, but many do.253-255 Subjective cognitive decline often prompts medical attention, and a proper diagnosis can help distinguish experiences that may relate to higher Alzheimer’s disease risk versus those with other contributors, including other underlying health conditions.256 One study showed those who over time consistently reported subjective cognitive decline that they found worrisome were at higher risk for developing Alzheimer’s dementia.257 The Behavioral Risk Factor Surveillance System survey, a large survey of people across the United States that includes questions on subjective cognitive decline, found that 10% of Americans age 45 and older reported subjective cognitive decline, but 54% of those who reported it had not consulted a health care professional.258 Individuals concerned about declines in memory and other cognitive abilities should consult a health care professional. 24 Alzheimer’s Association. 2022 Alzheimer’s Disease Facts and Figures. Alzheimers Dement 2022;18. Created from data from Chene et al.263 10.3% 19.5% 25 20 15 10 5 0 Age 45 65 11.6% 21.1% Percentage Men Women Estimated Lifetime Risk for Alzheimer’s Dementia, by Sex, at Ages 45 and 65 figure 4 Estimates of the Number of People with Alzheimer’s Dementia by State Based on projections shown in Figure 3 (see page 23), between 2020 and 2025 every state across the country will have experienced an increase of at least 6.7% in the number of people with Alzheimer’s. The prevalence estimates for 2020 and 2025, and changes between these two years, are shown in Table 4 (see page 22).A4,259 These projected increases in the number of people with Alzheimer’s are based primarily on projected changes in the population age 65 and older in these states, specifically the numbers of persons at each specific age (e.g., 66, 67, etc.). Based on changes over time in the age composition of their populations, the West and Southeast are expected to experience the largest percentage increases in people with Alzheimer’s dementia between 2020 and 2025. These increases will have a marked impact on states’ health care systems, as well as the Medicaid program, which covers the costs of long-term care and support for many older residents with dementia, including nearly a quarter of Medicare beneficiaries with Alzheimer’s or other dementias.260 The regional patterns of current and future burden do