%0 Journal Article %J J Alzheimers Dis %D 2018 %T Time Trends in the Prevalence of Neurocognitive Disorders and Cognitive Impairment in the United States: The Effects of Disease Severity and Improved Ascertainment. %A Akushevich, Igor %A Yashkin, Arseniy P %A Kravchenko, Julia %A Ukraintseva, Svetlana %A Stallard, Eric %A Yashin, Anatoliy I %X

BACKGROUND: Trends in the prevalence of cognitive impairment (CI) based on cognitive assessment instruments are often inconsistent with those of neurocognitive disorders (ND) based on Medicare claims records.

OBJECTIVE: We hypothesized that improved ascertainment and resulting decrease in disease severity at the time of diagnosis are responsible for this phenomenon.

METHODS: Using Medicare data linked to the Health and Retirement Study (1992-2012), we performed a joint analysis of trends in CI and ND to test our hypothesis.

RESULTS: We identified two major contributors to the divergent directions in CI and ND trends: reductions in disease severity explained more than 60% of the differences between CI and ND prevalence over the study period; the remaining 40% was explained by a decrease in the fraction of undiagnosed individuals.

DISCUSSION: Improvements in the diagnoses of ND diseases were a major contributor to reported trends in ND and CI. Recent forecasts of CI and ND trends in the U.S. may be overly pessimistic.

%B J Alzheimers Dis %V 64 %P 137-148 %8 2018 %G eng %N 1 %1 http://www.ncbi.nlm.nih.gov/pubmed/29865067?dopt=Abstract %R 10.3233/JAD-180060