Researchers from Bournemouth University in the United Kingdom looked at World Health Organization mortality statistics for 21 developed nations and compared the 1989-91 period with the 2008-10 time frame.
In the United States, death rates from dementia and other brain-related illnesses like Parkinson's disease and motor neuron disease spiked, jumping 82% for men and 48% for women in the age group of 55-74 years.
American men and women in this age group now have the second-highest neurological death rates in the developed world, behind Finland. In the earlier period, they ranked 17th and 11th, respectively. Elderly death rates from neurological causes leaped to 368% for men and 663% for women. Neurological causes now kill more elderly American women than cancer does.
Over the same time frame, death rates from cancer and cardiovascular disease dropped. For 55- to 74-year-olds, male cancer death rates dropped to 36% and female deaths reduced to 18%. Similar trends held true for heart-related diseases.
The researchers explained that "One obvious factor is that medical science has come up with all sorts of treatments to prolong the lives of people with cancer and cardiovascular conditions, while treatments for Alzheimer's have proven elusive. It could be simply that Alzheimer's and other neurological diseases are "diseases of the elderly"—that our brains are doomed to decline past a certain age, and more and more people are surviving cancer and heart disease only to develop diseases that they would not have lived long enough to have acquired in previous times."
The study's authors don't speculate much on what's driving the trends they identified; they suggest that lifestyle factors might play a role. Heather Snyder, director of medical and scientific relations at the Alzheimer's Association, told that there are significant but still-inconclusive links between cognitive decline and diet-related maladies like obesity and diabetes.