COPENHAGEN – The incidence of Alzheimer’s disease appears to be declining in the United States and may be following a similar positive trend in Germany as well.
An analysis of the ongoing Framingham Heart Study suggests that the disease has declined by 44% since 1978 in the United States, Claudia Satizabal, Ph.D., said at the Alzheimer’s Association International Conference 2014. Better management of cardiovascular risk factors and a generally higher education level seem to be driving the change.
"There has been a progressive decrease over that period," Dr. Satizabal of Boston University said during a press briefing. "Our results are in line with other studies from developed countries, and offer cautious hope that some cases might be preventable by managing risk – especially hypertension – and continuing to improve educational status."
She divided the Framingham study period into four epochs, beginning in 1978, 1989, and 1996, and finally, running from 2006 to 2013. She then calculated the 5-year incidence of Alzheimer’s disease in each of those periods, and according to gender and age of onset.
Using epoch 1 as the baseline, Dr. Satizabal found that overall incidence had decreased 22% by epoch 2. From epoch 2 to 3, she found a total decrease of 38% from baseline. From epoch 3 to 4, the total overall decrease was 44% from baseline.
The incidence reduction was somewhat greater in women, dropping 30% from baseline to epoch 1 to 2 and 48% from baseline to epoch 2 to 3. The decline then stabilized at a 47% decrease from baseline to epoch 3 to 4. The corresponding decreases among men were 4%, 11%, and 36%.
People who developed the disease also did so at a later age as the years progressed. The mean age of onset was 80 years in epoch 1, 82 in epoch 2, 84 in epoch 3, and 85 in epoch 4.
Education also influenced the reduction in incidence. Those with at least high school education had a consistent reduction in dementia incidence across all time periods, while those less educated did not.
"We also observed significant improvements in the use of antihypertensive and statin medication, blood pressure and cholesterol levels, and prevalence of smoking, heart disease, and stroke," Dr. Satizabal added.
However, she said, "our study looks at a small population of white Americans, so we can’t make the same assumptions about other populations."
Gabriele Doblhammer, Ph.D., of the German Center for Neurodegenerative Diseases in Rostock, had some similarly encouraging findings. Her study of short-term dementia trends in Germany – the first ever conducted – concluded that incidence is declining, age at onset is being pushed back, and disease duration has shortened.
"People seem to be enjoying more healthy years of life, and who would not want that?" she said.
Her study examined claims from the country’s largest public health insurer, which covers about 13% of the population overall, and 50% of older citizens.
The analysis comprised 6.5 million people and 600,000 dementia cases in those aged 65 and older, for the years 2007, 2008, and 2009. Over that period, new cases of dementia decreased for both men and women.
The results were better for women, however. For them, prevalence declined significantly: –3.6% from 2007 to 2008, and –1.8% from 2008 to 2009. Prevalence among men also decreased, but the change was not statistically significant. When women developed the disease, they died sooner – 10% more quickly in 2007 than in a sample obtained from 2004, suggesting that the disease was developing later in life, and much sooner to the time of normal expected death.
Neither Dr. Satizabal nor Dr. Doblhammer had any relevant financial disclosures.
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