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 1,225 individuals aged 66 or older. Receipt of a memory-related diagnosis was determined by ICD-9-CM codes. Incident cognitive impairment was defined as the first assessment wherein the subject’s modified Telephone Interview of 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% CI, 5.6% to 9.0%; p<0.001) 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.

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