The Association Between a Previous Diagnosis of Mild Cognitive Impairment as a Proxy for an Early Diagnosis of Dementia and Mortality: A Study of Secondary Care Electronic Health Records

Article type: Research Article

Authors: Couch, Elyse^{a; *} | Mueller, Christoph^{a; b} | Perera, Gayan^a | Lawrence, Vanessa^a | Prina, Matthew^a

Affiliations: [a] Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK | [B] South London and Maudsley NHS Foundation Trust, London, UK

Correspondence: [*] Correspondence to: Elyse Couch, Health Services and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London SE5 8AF, UK. Tel.: +44 020 7848 0714; E-mail: [email protected].

Abstract: Background:Dementia policy states that the early diagnosis of dementia can keep people living well for longer; however, there is little robust evidence to support this. Mild cognitive impairment (MCI) is considered a prodrome to dementia and can aid with the earlier diagnosis of dementia. Objective:The objective of this study was to use a previous diagnosis of MCI, before dementia, as a proxy for early diagnosis to investigate the relationship between an early diagnosis and mortality. Methods:A retrospective cohort study of electronic health care records from South London and Maudsley NHS. Patients aged 50+, diagnosed with dementia between January 2008 and November 2018, were divided into two groups: those with a previous diagnosis of MCI (early diagnosis) and those without. Cox regression models used to compare the risk of mortality between groups. Results:Of 18,557 participants, 5.6%(n = 1,030) had an early diagnosis; they had fewer cognitive, psychiatric, and functional problems at dementia diagnosis. The early diagnosis group had a reduced hazard of mortality (HR = 0.86, CI = 0.77–0.97). However, the magnitude of this effect depended on the scale used to adjust for cognitive difficulties. Conclusion:A previous diagnosis of MCI is a helpful proxy for early diagnosis. There is some evidence that an early diagnosis is associated with a reduced risk of mortality; however, it is not clear how Mini-Mental State Exam scores affect this relationship. While these findings are promising, we cannot be conclusive on the relationship between an early diagnosis and mortality.

Keywords: Alzheimer’s disease, dementia, early diagnosis, mild cognitive impairment, mortality

DOI: 10.3233/JAD-200978

Journal: Journal of Alzheimer's Disease, vol. 79, no. 1, pp. 267-274, 2021