Data on possible protective behaviours and dementia risk factors emerges at Alzheimer’s Association International Conference 2014 in Copenhagen
A third of Alzheimer’s cases are potentially preventable if people improve their lifestyles, according to a new study.
Factors including a lack of exercise, smoking and a lack of education can all contribute to the disease, and reducing the risk from these could prevent some nine million cases by 2050, the research published in The Lancet Neurology suggests.
The latest study, led by Carol Brayne from the Cambridge Institute of Public Health at the University of Cambridge and funded by the National Institute for Health Research, lowers the estimate from previous research in 2011 which had suggested as many as one in two cases are preventable.
The risk factors associated with Alzheimer’s disease are diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment.
It is thought that by 2050 more than 106 million people will have Alzheimer’s,up from 30 million sufferers in 2010. Deborah Barnes from the University of California, San Francisco and the San Francisco VA Medical Centre, who led the 2011 study and is a co-author on the new study, said the latest information could help to prevent and manage the disease in the future.
“It’s important that we have as accurate an estimate of the projected prevalence of Alzheimer’s as possible, as well as accurate estimates of the potential impact of lifestyle changes at a societal level,” said Barnes.
“Alzheimer’s disease is placing an ever increasing burden on health services worldwide as well as on both patients and carers.
“Our hope is that these estimates will help public health professionals and health policy makers design effective strategies to prevent and manage this disease.”
In separate research presented at the conference, results showed that regular eye tests could in future be used to diagnose early-stage Alzheimer’s, while a reduced sense of smell could also be an early indicator of dementia.
Potential strategies become clearer
☐ Poor sleep associated with higher risk in veterans
It is known that sleep disturbance is a risk factor for cognitive decline and dementia, but this association has not been carefully investigated in older veterans. At AAIC 2014, Kristine Yaffe, of the University of California, San Francisco and colleagues reported on the results of a retrospective study of sleep disturbance and dementia among 200,000 veterans age 55 and older, 96.5 per cent of whom were male.
The researchers examined eight years of the veterans’ medical records. After controlling for variables such as gender, income, education, and health status, they found that veterans who had a diagnosis of non-specific sleep disturbance, apnea, or insomnia at baseline had a 30 per cent increased risk of dementia compared with veterans with no diagnosed sleep problems. They also found that veterans with both PTSD and sleep disturbance had an 80 per cent increased risk of dementia.
☐ Late onset hypertension may protect against disease
While hypertension during midlife is considered to increase risk for Alzheimer’s disease and other dementia, there is emerging research evidence suggesting that its role in dementia risk may change over time, and may instead help protect against dementia in people age 90 and over, known as the “oldest old”. Maria Corrada, of the University of California, Irvine and colleagues investigated the relationship between risk of dementia, age of the onset of hypertension, and blood pressure measurements in the oldest old, and reported the results at AAIC 2014.
The researchers followed 625 participants every six months for up to 10 years in The 90+ Study, an ongoing longitudinal study of people age 90 and older. At enrollment, participants did not have dementia and were 93 years old on average; 69 per cent were female. The researchers found that participants with a hypertension onset age of 80 to 89 years had a significantly lower risk of developing dementia compared with participants with no history of hypertension. Participants with onset at age 90 or older had an even lower dementia risk.
The investigators also found that people with blood pressure levels in the hypertensive range had a significantly lower risk of developing dementia compared to people with blood pressure in the normal range. The association was independent of whether participants were taking medications that treat hypertension.