Rapidly accelerating rates of dementia worldwide will result in a 10% increase in the number of dementia sufferers in the 2005 to 2010 time frame, according to a new report from Alzheimer’s Disease International. The acceleration of cases will lead to an Alzheimer’s that will double every 20 years, resulting in an estimated 115 million dementia patients by mid-century, researchers said.

One expert called it “an emergency” that requires action because of the medical, economic and social implications from such big numbers. Currently, approximately 35.6 million people globally suffer from some form of dementia, 4.4 million of them in the United States, according to the 2009 World Alzheimer Report.

 As many as three-fourths of caregivers and family members of dementia patients said they have psychological difficulties due to the strain; up to one-third of those suffer from serious depression, report authors note. Researchers analyzed 147 studies from 21 areas of the world to reach their conclusions. Although low- and middle-income countries are likely to see the bulk of the increased number of dementia patients, the lack of a U.S. national plan to treat and fight Alzheimer’s and dementia could hurt its efforts to further research, prevention and treatment efforts.