State has highest estimated Alzheimer's cases in the U.S.

Alzheimer's — the most common form of dementia — is especially prevalent in California, according to a new Alzheimer's Association report, where an estimated 720,000 adults over the age of 65 suffer from the disease.

The state has a roughly 12% prevalence rate among the senior population, the seventh highest rate in the nation. As for the sheer number of people with Alzheimer's, California ranks No. 1. That number is only expected to grow, as the Golden State's population ages.

California is the most populated state in the country, and is also among one of the states with the oldest population. Approximately 12.7% of California's population is over the age of 85, according to 2020 demographics from the association.

The monthly journal published its 2023 Alzheimer's and Dementia research article in early July. The report looks at the prevalence of Alzheimer's disease in all 50 states and their 3,142 counties. The study looked at data from the Chicago Health and Aging Project and the National Center for Health Statistics to “determine the prevalence of Alzheimer's and Dementia in adults over 65.”

Southern California carries the bulk of the cases, with three counties — Los Angeles (No. 1), San Diego (No. 6) and Orange (No. 7) — with the highest number of people with AD dementia in the U.S. Imperial County was No. 9 for percent prevalence, with about 15% of people over 65 with dementia.

In comparison, Alzheimer's has less prevalence in Northern California compared to the southern half of the state, according to a map from the Alzheimer's Association.

Northern California counties ranged from 6% to 12% prevalence ranges, while Southern California counties ranged from 12% to 15%, according to the Alzheimer's Association map.

Florida has the second highest number of people with dementia, followed by Texas.

According to the U.S. Centers for Disease Control and Prevention, “scientists do not yet fully understand what causes Alzheimer's disease.” It is most prevalent in older adults, over the age of 65, but can affect those younger. It may also be linked to genetics.