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Estimate Of Worldwide Prevalence Of Alzheimer's Disease Is 26.6 Million

Armen Hareyan's picture

The latest worldwide estimate of Alzheimer's disease prevalence shows that 26.6 million people were living with the disease in 2006.

The researchers predict that global prevalence of Alzheimer's will quadruple by 2050 to more than 100 million, at which time 1 in 85 persons worldwide will be living with the disease. More than 40 percent of those cases will be in late stage Alzheimer's requiring a high level of attention equivalent to nursing home care.

"The number of people affected by Alzheimer's disease is growing at an alarming rate, and the increasing financial and personal costs will have a devastating effect on the world's economies, healthcare systems and families," said William Thies, Ph.D., vice president of Medical and Scientific Relations with the Alzheimer's Association. "We must make the fight against Alzheimer's a national priority before it's too late. The absence of effective disease modifying drugs, coupled with an aging population, makes Alzheimer's the healthcare crisis of the 21st century."

"However there is hope. There are several drugs in Phase III clinical trials for Alzheimer's that show great promise to slow or stop the progression of the disease. This, combined with advancements in diagnostic tools, has the potential to change the landscape of Alzheimer's, but we need more funding for research to make this happen," Thies said.

Researchers led by Ron Brookmeyer, PhD, Professor of Biostatistics and Chair of the Master of Public Health Program at The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, created a multi-state mathematical computer model using United Nations' worldwide population forecasts and data from epidemiological studies on the incidence and mortality of Alzheimer's. The goal was to forecast the global burden of Alzheimer's disease and evaluate the potential impact of interventions that delay disease onset or progression.

The researchers also used their model to investigate the impact of medical advances and preventive strategies on disease onset and disease progression. They found that:

-- Delaying Alzheimer's disease onset by one year we would reduce the number of Alzheimer's cases in 2050 by 12 million.

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-- Delaying both Alzheimer's disease onset and disease progression by two years would reduce burden by more than 18 million cases, with most of that decrease -- 16 million cases -- among late stage cases that require the most intensive care.

"A global epidemic of Alzheimer's disease is coming," Brookmeyer said. "However, even modest advances in preventing Alzheimer's or delaying its progression can have a huge global public health impact."

Doubling Time of Alzheimer's Disease Incidence

In a related study, Kathryn Ziegler-Graham, PhD, a National Science Foundation post-doctoral fellow and visiting assistant professor in Statistics at St. Olaf College in Northfield, Minn., and colleagues examined Alzheimer's disease doubling time, which is the number of years it takes for the age- specific incidence rate to double.

In order to estimate doubling times and identify regional or gender relationships, the researchers reviewed all studies in the peer review literature that reported age specific incidence rates for Alzheimer's disease. They found an overall estimate of the doubling time was 5.5 years. The doubling times from studies performed in North America, Europe, and other parts of the world were not significantly different. No significant differences were detected by gender.

"Doubling times of Alzheimer's disease incidence rates are remarkably similar among populations throughout the world," Ziegler-Graham said.

In March, the Alzheimer's Association reported that there are now more than 5 million people in the United States living with Alzheimer's. This is a 10 percent increase from the previous nationwide prevalence estimate of 4.5 million. The new estimate was included in a report titled, 2007 Alzheimer's Disease Facts and Figures.

"The astronomical costs of Alzheimer's disease and other forms of dementia have a tremendous impact on individuals living with the disease, their loved ones and society as a whole," said Harry Johns, president and CEO of the Alzheimer's Association. "We must increase funding for research on treatment, prevention and early detection. And until we defeat this disease, we must provide better care for people with dementia and their families. The advancements we make in treatment and prevention now will save millions of dollars and lives in the near future."