Regional variation in diagnostic intensity of dementia among older US adults: An observational study

Dear Editor,

We have read the recent study by Bynum et al., titled “Regional variation in diagnostic intensity of dementia among older U.S. adults: An observational study,” with great interest.¹ This research provides important insights into the regional disparities in the diagnosis of Alzheimer's disease and related dementias (ADRD) in the United States. We would like to offer a few comments on the study's findings, specifically regarding the unexplained variation in diagnostic intensity and the potential impact of health-care practices and patient behaviors.

First, we commend the authors for their comprehensive approach in adjusting for demographic, socioeconomic, and health-related factors across different hospital referral regions (HRRs). The finding that ≈ 33% of the regional variation in ADRD diagnostic intensity remains unexplained after accounting for these factors is intriguing. This highlights a significant gap in our understanding of the drivers behind these disparities and suggests that other, less quantifiable factors are at play.

One potential explanation for this unexplained variation lies in differences in clinical practices across regions. As the authors suggest, regional differences in the availability and use of diagnostic tools, as well as variations in physician training and experience, likely contribute to the observed disparities. For instance, regions with higher diagnostic intensity may benefit from a greater concentration of specialists, access to advanced neuroimaging technologies, or established protocols for early detection of cognitive decline.² Conversely, regions with lower diagnostic intensity may be hindered by a lack of these resources or by clinicians who are less experienced in recognizing the early signs of dementia.³

Another important consideration is the role of patient behaviors and cultural factors. As the authors note, patient health-seeking behavior can vary significantly across regions, influenced by factors such as health literacy, stigma associated with cognitive decline, and trust in the health-care system. These factors may contribute to delayed diagnoses in certain regions, particularly among minority populations or those with limited access to care.⁴ Future research could explore how interventions aimed at increasing awareness of dementia and reducing barriers to care might help mitigate these disparities.⁵

Furthermore, while the study provides valuable insights into diagnostic intensity, it raises important questions about the consequences of both under- and overdiagnosis. Regions with lower diagnostic intensity may suffer from underdiagnosis, potentially depriving patients of early interventions that could improve quality of life. Conversely, regions with higher diagnostic intensity may risk overdiagnosis, leading to unnecessary treatments or heightened anxiety among patients and families.⁶ It would be beneficial for future studies to examine the clinical outcomes associated with varying levels of diagnostic intensity to ensure that the right balance is struck between timely diagnosis and avoiding unnecessary medicalization.⁷

We propose incorporating a three-tiered prevention framework to address these variations: primary, secondary, and tertiary prevention. Primary prevention focuses on reducing risk factors, such as improving cardiovascular health and mitigating environmental hazards, which vary by region. Secondary prevention emphasizes early diagnosis through standardized screening, ensuring timely identification regardless of geography. Last, tertiary prevention aims to enhance care for diagnosed individuals, providing personalized interventions to slow progression and improve quality of life. By adopting this prevention approach, we can reduce regional disparities and ensure equitable access to dementia care across the country.

In summary, this study highlights critical disparities in dementia diagnosis across the United States and underscores the need for more research into the underlying causes of these variations. Addressing the regional differences in health-care practices, patient behaviors, and health-care access will be crucial in ensuring that all individuals, regardless of where they live, receive timely and accurate diagnoses of ADRD.