People with mild cognitive impairment (MCI) who engage in as little as 10 minutes of moderate to vigorous exercise a few times a week may be helping to slow the progression to Alzheimer’s or similar dementia, new research suggests. MCI, a decline in memory and thinking skills beyond what occurs normally with aging, is considered an early steppingstone to more serious dementia, although not everyone with MCI progresses to Alzheimer’s. About 15 to 20 percent of people older than 65 have MCI, according to the Alzheimer’s Association. No medications have been approved by the Food and Drug Administration to treat MCI, and drugs approved to treat Alzheimer’s symptoms have not been shown to delay or prevent the progression from MCI to dementia. The new study, published in the journal Alzheimer’s Research and Therapy, was based on about six years of data on 247,149 people, most in their mid- to late 60s, who had been diagnosed with MCI. It found the largest reduction in risk of progression (18 percent) for those who exercised regularly before being diagnosed and continued exercising after the diagnosis. But even those who did not start exercising until after getting an MCI diagnosis were 11 percent less likely to progress to Alzheimer’s than were those who did not exercise at all. The researchers speculate that exercise may be beneficial to those with MCI because it supports the production of brain cells (neurons) and increases blood flow to the brain, limiting shrinkage in the brain that has been linked to dementia.