Evaluation of dementia

Dementia is a syndrome characterized by deterioration in cognition, resulting in impairment in the activities of daily living. Cognitive decline occurs in one or more cognitive domains.[1]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed., text revision (DSM-5-TR). Washington, DC: American Psychiatric Publishing; 2022.

The incidence of dementia doubles with every 6.3 year increase in age, from 3.9 per 1000 person-years at age 60-64, to 104.8 per 1000 person-years at age 90 and over.[2]Prince M, Wimo A, Guerchet M, et al. Alzheimer's Disease International. World Alzheimer Report 2015. Aug 2015 [internet publication]. https://www.alzint.org/u/WorldAlzheimerReport2015.pdf

The global number of individuals living with dementia increased from 20.2 million in 1990, to 58.7 million in 2020.[3]GBD 2016 Dementia Collaborators. Global, regional, and national burden of Alzheimer's disease and other dementias, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Neurol. 2019 Jan;18(1):88-106. https://www.doi.org/10.1016/S1474-4422(18)30403-4 http://www.ncbi.nlm.nih.gov/pubmed/30497964?tool=bestpractice.com [4]Alzheimer's Disease International. Numbers of people with dementia worldwide: an update to the estimates in the World Alzheimer Report 2015. Nov 2020 [internet publication]​. https://www.alzint.org/resource/numbers-of-people-with-dementia-worldwide ​​​​​​ The number of people estimated to be living with dementia in 2050 is 152.8 million people.[5]GBD 2019 Dementia Forecasting Collaborators. Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050: an analysis for the Global Burden of Disease Study 2019. Lancet Public Health. 2022 Feb;7(2):e105-25. https://pmc.ncbi.nlm.nih.gov/articles/PMC8810394 http://www.ncbi.nlm.nih.gov/pubmed/34998485?tool=bestpractice.com ​ Dementia was the seventh leading cause of death globally in 2019, accounting for 1.6 million deaths.[6]World Health Organization. Global status report on the public health response to dementia. Sep 2021 [internet publication]. https://www.who.int/publications/i/item/9789240033245 ​ 

In the US, 4% of adults ages 65 years and older reported a dementia diagnosis in 2022.[7]Kramarow EA. Diagnosed dementia in adults age 65 and older: United States, 2022. Natl Health Stat Report. 2024 Jun;(203):1-9. https://www.cdc.gov/nchs//data/nhsr/nhsr203.pdf http://www.ncbi.nlm.nih.gov/pubmed/38912900?tool=bestpractice.com ​ Socially disadvantaged groups, including Black people, Asian and other minority ethnic groups, are particularly at risk.[8]Livingston G, Huntley J, Sommerlad A, et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. 2020 Aug 8;396(10248):413-46. https://pmc.ncbi.nlm.nih.gov/articles/PMC7392084 [9]Manly JJ, Jones RN, Langa KM, et al. Estimating the prevalence of dementia and mild cognitive impairment in the US: the 2016 health and retirement study harmonized cognitive assessment protocol project. JAMA Neurol. 2022 Dec 1;79(12):1242-9. https://pmc.ncbi.nlm.nih.gov/articles/PMC9593315 http://www.ncbi.nlm.nih.gov/pubmed/36279130?tool=bestpractice.com ​​

The majority of cases of dementia have degenerative and vascular causes.[10]Goodman RA, Lochner KA, Thambisetty M, et al. Prevalence of dementia subtypes in United States Medicare fee-for-service beneficiaries, 2011-2013. Alzheimers Dement. 2017 Jan;13(1):28-37. https://www.doi.org/10.1016/j.jalz.2016.04.002 http://www.ncbi.nlm.nih.gov/pubmed/27172148?tool=bestpractice.com Other causes include infections, inflammatory diseases, neoplasm, toxic insults, metabolic disorders, and trauma.

An estimated 11% to 14% of dementias are caused by potentially reversible conditions; therefore, ruling out these conditions is important when considering a diagnosis of dementia.[11]Clarfield AM. The reversible dementias: do they reverse? Ann Intern Med. 1988 Sep 15;109(6):476-86. http://www.ncbi.nlm.nih.gov/pubmed/3046450?tool=bestpractice.com [12]Clarfield AM. The decreasing prevalence of reversible dementias: an updated meta-analysis. Arch Intern Med. 2003 Oct 13;163(18):2219-29. http://www.ncbi.nlm.nih.gov/pubmed/14557220?tool=bestpractice.com