One in three cases of Alzheimer's disease worldwide is preventable, according to research from the University of Cambridge.
The main risk factors for the disease are a lack of exercise, smoking, depression and poor education, it says.
Previous research from 2011 put the estimate at one in two cases, but this new study takes into account overlapping risk factors.
Alzheimer's Research UK said age was still the biggest risk factor.
Writing in The Lancet Neurology, the Cambridge team analysed population-based data to work out the main seven risk factors for Alzheimer's disease.
Low educational attainment
They worked out that a third of Alzheimer's cases could be linked to lifestyle factors that could be modified, such as lack of exercise and smoking. ...more
What is Alzheimer's disease?
Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills and, eventually even the ability to carry out the simplest tasks of daily living. In most people with Alzheimer’s, symptoms first appear after age 60. Alzheimer’s disease is the most common cause of dementiaamong older people.
The disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles).
Plaques and tangles in the brain are two of the main features of Alzheimer’s disease. The third is the loss of connections between nerve cells (neurons) in the brain.
Although treatment can help manage symptoms in some people, currently there is no cure for this devastating disease.
What happens to the brain in Alzheimer's disease?
Although we still don’t know how the Alzheimer’s disease process begins, it seems likely that damage to the brain starts a decade or more before problems become evident. During the preclinical stage of Alzheimer’s disease, people are free of symptoms, but toxic changes are taking place in the brain. Abnormal deposits of proteins form amyloid plaques and tau tangles throughout the brain, and once-healthy neurons begin to work less efficiently. Over time, neurons lose the ability to function and communicate with each other, and eventually they die.
Before long, the damage spreads to a nearby structure in the brain called the hippocampus, which is essential in forming memories. As more neurons die, affected brain regions begin to shrink. By the final stage of Alzheimer’s, damage is widespread, and brain tissue has shrunk significantly. ...more
How many Americans have Alzheimer’s disease?
Estimates vary, but experts suggest that as many as 5 million Americans age 65 and older have Alzheimer’s disease. Unless the disease can be effectively treated or prevented, the number of people with it will increase significantly if current population trends continue. That’s because the risk of Alzheimer’s increases with age, and the U.S. population is aging. The number of people with Alzheimer’s doubles for every 5-year interval beyond age 65. ...more