Geriatric massage is a growing specialty—and massage for Alzheimer’s and dementia patients is a sub-specialty that could see increased demand as the U.S. population ages.

According to a new study, dementia in the very elderly—those over 90—is expected to become “epidemic.”

University of California researchers found the incidence rate for all causes of dementia in people age 90 and older is 18.2 percent annually, and significantly increases with age in both men and women.

Dementia is a progressive, degenerative disorder that affects language, attention, memory, emotions and problem-solving capabilities. A variety of diseases cause dementia, including Alzheimer’s disease, stroke and other neurodegenerative disorders, according to  University of California press release.

For this study, analysis was completed on 330 participants who were primarily women (69.7 percent) between the ages of 90 to 102, and who showed no signs of dementia at baseline, according to the press release. Researchers identified 140 new cases of dementia during follow-up, with 60 percent of those cases attributed to Alzheimer’s disease 22 percent vascular dementia, 9 percent mixed Alzheimer’s disease and vascular dementia and 9 percent with other or unknown cause.

“Our findings show dementia incidence rates almost double every five years in those 90 and older,” researcher Maria Corrada, Sc.D., explained.

Prior reports estimate there were 2 million Americans aged 90 and older in 2007 and the number is expected to reach 8.7 million by 2050, making the oldest-old the fastest growing segment of the U.S. population.

Findings of the study appeared recently in the journal Annals of Neurology.