"Recent animal studies suggest that vascular risk factors play roles in the development of Alzheimer's disease," says researcher Yan-Jiang Wang, MD, PhD, a professor of neurology at Third Military Medical University in Chongqing, China.
"But it still remains unclear whether vascular risk factors cause Alzheimer's disease in humans," he tells WebMD in an email. "Our study provides important evidence in humans which supports the idea that vascular risk factors play a critical role in the development of Alzheimer's disease."
Reducing the Risk of Alzheimer's Disease: Study Details
The researchers enrolled 837 men and women, all aged 55 and older.
All had a condition known as mild cognitive impairment (MCI), which is a mental condition less severe than dementia, with symptoms such as forgetting recent events, difficulty multitasking, and taking longer to perform mental tasks. MCI increases the risk of progressing to Alzheimer's disease.
Wang's team evaluated the participants each year for five years with standard tests of cognitive function and their ability to do daily activities.
After some dropped out, 650 completed the follow-up. During that time, 298 progressed to Alzheimer's, while the others remained with mild cognitive impairment. Participants who had vascular risk factors were twice as likely to develop Alzheimer's over the five-year follow-up as those who did not have any of the vascular risk factors.
However, study participants who received treatment for all their vascular risk factors were 39% less likely to get Alzheimer's disease over the follow-up period than those who got no treatment.
Even treating some of the risk factors helped. It reduced the risk of progression by 26%.
The study is strictly observational, the researchers say. Therefore, it cannot prove cause and effect. However, they write, ''active intervention for vascular risk factors might reduce progression in MCI to Alzheimer's disease dementia."
Although the link is not proven, Wang tells WebMD ''there would be no downside to treating the vascular risk factors."