Rural and Urban Differences in Dementia Diagnosis in the Western U.S

TL;DR

This study found that dementia diagnosis rates are generally lower in rural areas compared to urban areas across eight Western U.S. states.

Contribution

The study provides new evidence of rural-urban differences in dementia diagnosis within the Western U.S. using a single health system's data.

Findings

ADRD diagnosed prevalence was 5.4% in urban areas versus 4.7% in rural areas (p < 0.001).

Seven out of eight states showed lower diagnosed prevalence in rural areas compared to urban areas.

New Mexico had the lowest overall diagnosed prevalence at 2.3%, while Oregon and Montana had the highest at 6.6% and 6.5%.

Abstract

Prior research suggests diagnostic prevalence of Alzheimer’s disease and related dementias (ADRD) is lower in rural U.S., though noted geographic variations have been observed in studies of the southern and Midwest regions. We compared rural and urban diagnosed prevalence of ADRD and cognitive impairment in eight Western states: Alaska, California, Idaho, Montana, New Mexico, Oregon, Texas, Washington. Diagnostic codes for ADRD and cognitive impairment from Providence Health system’s electronic medical records were pulled from Jan. 1, 2018-June 30, 2025 for all active patients. Of 6,911,104 patients (min=Idaho: 45,160; max=California: 2.46 million), we observed a substantial difference in overall diagnosed prevalence across states of residence: Oregon and Montana had the highest diagnosed prevalence (6.6% and 6.5%, respectively); New Mexico had the lowest (2.3%). Overall diagnosed prevalence among those residing in urban and high commuting areas (RUCA 1-3, 4.1, 5.1, 8.1, 10.1) was 5.4% versus 4.7% among those residing in rural and low commuting areas (p < 0.001). Within-state urban versus rural differences in diagnosed prevalence was estimated for Alaska (4.8% vs. 3.5%; p < 0.001), California (4.8% vs. 4.2%; p < 0.001), Montana (7.3% urban vs. 5.1% rural; p < 0.001), New Mexico (3.2% vs. 2.2%; p = 0.01), Oregon (6.7% vs. 5.9%; p < 0.001), Texas (3.9% vs. 3.3%; p < 0.001) and Washington (6.3% vs. 5.3%; p < 0.001), but not for Idaho (3.5% vs. 3.4%; p = 0.57). Our findings within a single health system indicate lower ADRD diagnosed prevalence among patients residing in rural areas in 7 of the 8 states examined, suggesting a pattern of lower health system access and diagnosis.