As of 2015, nearly 47 million people around the world had dementia, a memory problem significant enough to affect your ability to carry out your usual tasks. The most common cause of dementia is Alzheimer’s disease, but other forms exist, too.

Because there’s currently no cure for dementia, it’s important to know about the risk factors that may lead to developing it. For example, researchers have learned that older adults with slower walking speeds seem to have a greater risk of dementia than those with faster walking speeds. Recently, researchers from the United Kingdom teamed up to learn more about changes in walking speed, changes in the ability to think and make decisions, and dementia. They published their study in the Journal of the American Geriatrics Society.

The researchers examined information collected from the English Longitudinal Study of Aging. The study included adults aged 60 and older who lived in England. In their study, the researchers used information collected from 2002 to 2015. They assessed participants’ walking speed on two occasions in 2002-2003 and in 2004-2005, and whether or not the participants developed dementia after the tests from 2006-2015. Then, they compared the people who had developed dementia with those who had not.

Researchers discovered that of the nearly 4,000 older adults they studied, those with a slower walking speed had a greater risk of developing dementia. And people who experienced a faster decline in walking speed over a 2-year period were also at higher risk for dementia. People who had a poorer ability to think and make decisions when they entered the study—and those whose cognitive (thinking) abilities declined more quickly during the study—were also more likely to be diagnosed with dementia.

The researchers concluded that older adults with slower walking speeds, and those who experienced a greater decline in their walking speed over time, were at increased risk for dementia. But, the researchers noted, changes in walking speed and changes in an older adult’s ability to think and make decisions do not necessarily work together to affect the risk of developing dementia.