Dementia Prevalence in Orange County

Alzheimer’s Orange County (AlzOC) has just released new figures about dementia prevalence in Orange County that show that more people than ever are being impacted by some form of cognitive impairment in our community. According to the new estimate, 164,346 Orange County residents have dementia or mild cognitive impairment (MCI). This new data highlights the pressing need for increased support and resources for individuals and families affected by these conditions.

Use the information and toolkit below to help us spread awareness and start a conversation about the impact of dementia so more can people can get the local support they need.

Over 164,000 people in Orange County are estimated to be affected by dementia or mild cognitive impairment (MCI).

Press Release

Read and download the full press release. For media inquiries, please email

What is mild cognitive impairment?

Learn more about what mild cognitive impairment (MCI) is, what are the symptoms, and how it’s related to dementia.

Dementia Prevalence Fact Sheet

View additional figures from AlzOC’s new estimate and check out supplemental facts about dementia and MCI.

Graphics and Toolkit

View and download valuable resources and insights from our toolkit to raise awareness and promote understanding of this growing issue.



AlzOC utilized federal census data and adjusted the number of people aged 65 years or older in Orange County using the published County of Orange number of seniors. We then overlayed that number (497,346) with ethnicity, as stated in the federal census.

We applied widely published dementia prevalence figures from peer-reviewed studies indicating the percentage of people who experience a condition like dementia or mild cognitive impairment to the population data for Orange County. 

Following this methodology, we extrapolated the number of people with some form of dementia in Orange County, the number of people with mild cognitive impairment (MCI), and, therefore, the number of seniors in Orange County with some form of cognitive impairment.*

*Disclaimer: these numbers are estimates using widely published and generally accepted prevalence and census figures. Gender and younger onset dementia or dementia occurring before 65 have not been factored into these figures.


Alzheimer’s Association. (2020). Race, Ethnicity, and Alzheimer’s.  
Columbia University Irving Medical Center. (2022, October 24). One in 10 Older Americans Has Dementia. 
U.S Census Bureau. (2022, July). Quick Facts : Orange County, California. 
USA Facts. (2022, July). Our Changing Population: Orange County, California. population/state/california/county/orange-county