Prevalence of Memory-Related Diagnoses among U.S. Older Adults with Early Symptoms of Cognitive Impairment

Background: Early diagnosis of cognitive impairment may confer important advantages. Yet the prevalence of memory-related diagnoses among older adults with early symptoms of cognitive impairment is unknown. Methods: A retrospective, longitudinal cohort design using 2000-2014 Health and Retirement Survey-Medicare linked data. We leveraged within-individual variation to examine the relationship between incident cognitive impairment and receipt of diagnosis among 1225 individuals aged 66 or older. Receipt of a memory-related diagnosis was determined by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Incident cognitive impairment was defined as the first assessment wherein the participant's modified Telephone Interview for Cognitive Status score was less than 12. Results: The unadjusted prevalence of memory-related diagnosis at cognitive impairment was 12.0%. Incident cognitive impairment was associated with a 7.3% (95% confidence interval [CI], 5.6% to 9.0%; p <. 001) higher adjusted probability of any memory-related diagnosis overall, yielding 9.8% adjusted prevalence of diagnosis. The increase in likelihood of diagnosis associated with cognitive decline was significantly higher among non-Hispanic Whites than non-Hispanic Blacks (8.2% vs -0.7%), and among those with at least a college degree than those with a high school diploma or less (17.4% vs 6.8% vs 1.6%). Those who were younger, had below-median wealth, or without a partner had lower probability of diagnosis than their counterparts. Conclusions: We found overall low prevalence of early diagnosis, or high rate of underdiagnosis, among older adults showing symptoms of cognitive impairment, especially among non-Whites and socioeconomically disadvantaged subgroups. Our findings call for targeted interventions to improve the rate of early diagnosis, especially among vulnerable populations.