The number of people living with Alzheimer's disease will at least double by 2050 even if major treatment breakthroughs should occur over the coming decades, according to a report from the University of North Carolina released in the Annual Review of Public Health.
Dr. Philip D. Sloane, the report's principal author and Elizabeth and Oscar Goodwin Distinguished Professor of Family Medicine in the UNC School of Medicine said the prevalence of Alzheimer's rises quickly after age 85. Persons beyond that age have 14 times the incidence of the disease compared with those aged 65 to 69.
"The U.S. population in the next decades is expected to have so many people over 85 that the growth rate of people with Alzheimer's disease will be much greater than that of the population," he said.
Previous projections, including conservative figures from the U.S. General Accounting Office, pointed to a four-fold increase should there be no significant Alzheimer's treatment advances to alter the number of people with the disease or to slow its progression. Based on those projections, between 7.98 and 12.95 million people in the United States will be living with the illness by the year 2050.
However, whether a two-fold or four-fold increase, management of Alzheimer's disease "will undoubtedly be a major and growing public health issue during the first half of the twenty-first century," the new report stated. "The projected increase in Alzheimer's disease will need to be paralleled by efforts to assure the availability and quality of care for persons with the disease."
Sloane, co-director of the Program on Aging, Disability and Long-term Care at the university's Cecil G. Sheps Center for Health Services Research, said the study was instigated by a widely held view that Alzheimer's disease will not be the same threat in twenty years because of advances in science.
"It occurred to us that people have no guidance to project what will happen in the future regarding Alzheimer's. Published studies have made no projections based on scientific advances. This study was an attempt to assign some numbers to what would happen in Alzheimer's disease if there really are treatment breakthroughs, which we expect there will be."
To statistically model the potential magnitude and nature of the effect of these advances, Dr. Chirayath Suchindran of UNC's School of Public Health and biostatistician for the study team used historical data from congestive heart failure (CHF) and Parkinson's disease (PD), two chronic diseases affecting older persons and that have seen significant treatment advances over the last 50 years.
In Parkinson's disease, introduction of levodopa and related medications altered the course of the illness, doubling the length of time patients spend in each of the five disease stages. Treatments for hypertension and reduction of coronary artery disease have helped delay the onset of congestive heart failure. In the 1950s, the average age of disease onset was 57.3 years. By the 1980s, it was 76.4 years.
In projecting the impact of drug development on Alzheimer's disease prevalence and stages, the authors developed modified statistical projections based on the three scenarios provided by the models: delayed disease onset (CHF model), reduced rate of progression (PD model), and combined delayed onset/reduced progression (CHF/PD). Each represented a projection based on one or more breakthroughs in therapy being introduced into the general population by 2010.
A successful method of delaying disease onset could reduce the overall projected number of people with AD by 38 percent in 2050, becoming 6.31 million. Of these, 2.10 (33 percent) will be mild and 4.21 (67 percent) will have moderate to severe disease.
However, the overall burden on the private and public health system would still increase threefold over current estimates. The long-term care industry would require major transformation.
If successful treatments to slow disease progression became readily available by 2010, then 10.33 million elderly will have AD by 2050, virtually the same as if no change in treatment occurred, "but the preponderance of persons with the disease will be mild cases (59 percent)," according to the report.
This would result in a shift away from institutional care, as has already been modestly demonstrated in studies of patients taking some of the newer medications (cholinesterase inhibitors) that can delay disease progression by six to nine months.
Dr. Sheryl Zimmerman, associate professor of social work and public health and co-director of the Program on Aging, Disability and Long-Term Care of the Sheps Center concluded that "the net effect would be to increase the burden on families by requiring additional years of caregiving," adding that additional outpatient support services would likely be needed. Thus, whole new modes of care would need to be developed, such as outpatient clinics devoted to Alzheimer's care, expanded dementia day programs and respite care services for caregivers.
"The most promising model is one that involves both delayed onset and retarded disease progression," the authors said. The total number of AD cases would be 6.39 million but the majority (56 percent) would be mild. This model would result in continued growth in our systems of care, but largely in outpatient services. Long-term care would grow only modestly.
"The lesson we learn from all this is that the disease is not going to go away if we have significant treatment advances," Sloane said, noting that the introduction of significant new therapies would rapidly change the health services needs of people with Alzheimer's disease. "And that means that the health system must begin thinking ahead and preparing for these eventualities, particularly as drugs begin to make it through clinical trials."