Alzheimer's disease, a fatal, progressive brain disease characterized by severe dementia, is the sixth most common disease that ends in death statewide, and it is increasing more rapidly than other leading causes of death. The study found that Californians age 55 and older have a 1 in 8 chance of developing the disease.

"The numbers don't lie. The state of California will be greatly impacted by this disease as Baby Boomers age," Senate Pro Tem Darrell Steinberg said in a statement about the report. "Policymakers will need to work with experts and community members on a plan to lessen the impact of Alzheimer's on our citizens, economy and health care systems."

Families provide the vast majority - nearly three-quarters - of all formal and informal care, the report found.

Informal care, or services typically provided by family members, is expected to increase in value from about $37.2 billion now to $72.7 billion in unpaid care by 2030. Formal services, traditional medical and social services that exclude nursing home care, are also expected to double, from $16 billion to about $31.3 billion over the next two decades, the report found.

The report estimates that the cost for people living in nursing homes will increase from $2.7 billion in 2008 to $5.2 billion 2030.

The report did not estimate the increased cost to Medi-Cal, the federal and state health program for the poor, because it lacked the data, said Patrick Fox, professor of sociology and health policy at UC San Francisco and author of the report.

Fox said it's 2 1/2 times more costly to care for a Medi-Cal patient over the age of 65 with Alzheimer's than a Medi-Cal patient of that age with any other diagnosis that excludes dementia. "That's largely driven by the fact that Medi-Cal pays for nursing home care," he said.

Sherrie Matza, a 59-year-old business consultant from San Francisco, understands the cost of the disease on caregivers and families first hand.

Matza cared for her mother in her home for eight years before moving her to a nursing home, where she lived for five years until her death in 2000. Matza said the nursing-home care cost at least three times as much as the in-home care she hired while she was working.

"We have to make sure long-term services and support are a part of the health care reform dialog," said Matza, who has since become a volunteer advocate for Alzheimer's-related causes.

But Matza said the biggest investment in the disease should be in scientific research. "If we can just delay the onset of the most horrible symptoms of the disease that require 24-hour care, we can cut the prevalence in half," she said.

The report, "Alzheimer's Disease, Facts and Figures in California," was funded by the Rosalinde and Arthur Gilbert Foundation and supported by the Alzheimer's Disease Program at the California Department of Public Health.