Although genetics plays a role in the development of Alzheimer’s disease and other types of dementia, lifestyle factors are also involved.
Declines in other sensory functions — vision, touch and hearing — were also found to be associated with an increased risk of dementia, but not nearly as strongly.
People in their 70s and 80s who adhere to four or five behaviors — a high-quality diet, regular physical activity, not smoking, light-to-moderate alcohol consumption and staying intellectually engaged — are 60 percent less likely to develop Alzheimer’s disease over the next decade of their life than others.
Three areas of cognitive skills showed the most decline: episodic memory, working memory and perceptual speed.
Changes in the brain associated with dementia can start 15 to 20 years before any clinical symptoms appear.
The study found that people with a high genetic risk were about a third less likely to develop dementia if they followed a healthy lifestyle than if they didn’t.
A large majority of the adults who were polled said they take supplements or solve puzzles to keep their brains healthy — two strategies that have not been shown to be effective at enhancing memory or warding off dementia.
A poor sense of smell is already known to be an early sign of dementia and Parkinson’s disease.
The findings held true for both the healthy adults and those diagnosed with Alzheimer’s disease, although the seasonal differences were smaller among those with dementia.
Older adults who successfully followed seven heart-healthy actions recommended by the American Heart Association were significantly less likely to develop dementia in their later years.
“I was disappointed by the results, although I probably wasn’t completely surprised,” said Sarah Lamb, the study’s lead author and a researcher at Oxford University.
The Dementia-Friendly Community concept was developed in the UK and has spread throughout the U.S. Some 70 Minnesota communities now have earned Dementia-Friendly designation.
“There is no magic bullet,” said Mary Butler, one of the authors of the review and co-director of the Minnesota Evidence-based Practice Center.
This report also marks a major change in thinking among dementia experts.
Minnesota’s age-adjusted Alzheimer’s death rate rose from 21.1 per 100,000 people in 1999 to 24.2 in 2014 — a 14.5 percent increase.
“Regular physical activity, such as walking, and a heart-healthy diet have much more evidence supporting their effectiveness for reducing dementia risk,” said co-author Frederick Schmitt.
The rates of palliative-care consultations and do-not-resuscitate orders are higher among patients with cancer or dementia.
The study, which was published this week in the journal Anesthesiology, involved more than 8,500 middle-aged and elderly Danish twins.
“Our study offers cautious hope that some cases of dementia might be preventable or at least delayed,” write the authors of the study.
The study’s findings are intriguing, but they are a long way from being translated into any practical applications, as the NHS experts point out.