The word—an acronym, really—is FAST, and it stands for Face drooping, Arm weakness, Speech difficulty, Time to call 911. FAST has long been used as a mnemonic tool to help people recognize when they or someone else might be having a stroke, and act quickly to summon an ambulance. The American Stroke Association (ASA) features the acronym in its stroke education materials for the general public.

Although studies show that FAST is an effective teaching tool, it’s also imperfect. Strokes can cause a range of sudden signs and symptoms—including dizziness and balance problems, difficulty seeing from one or both eyes, and severe headache—but FAST captures only a few of the most common ones. Research suggests that relying on FAST alone misses up to 14 percent of strokes. That shortfall led experts to develop a longer mnemonic called BE-FAST, which adds balance and eyesight problems to the mix. Many U.S. hospitals now use BE-FAST in their stroke education campaigns.

There’s a problem, however: It’s not clear that BE-FAST actually does improve the average person’s ability to spot a possible stroke. In fact, some recent research suggests the original mnemonic is the better screening tool.

FAST vs. BE-FAST

The latest study, presented in February at the ASA’s International Stroke Conference, found that FAST may simply be easier for people to recall. Researchers randomly assigned nearly 2,000 U.S. adults to watch a short video that taught them either the FAST or BE-FAST stroke warning signs—and overall, the FAST approach worked better: Right after viewing the video, 70 percent of the FAST group could identify what the F, A, and S represent, versus only half of the BE-FAST group. A month later, recollections had faded in both groups, but people who had learned the FAST warning signs still had better recall.

Because that study was reported at a medical meeting and is not yet published in a peer-reviewed journal, the findings have to be considered preliminary. But another study, published last October in the Journal of the American Heart Association, reached similar conclusions. It involved 174 adults who were randomly assigned to learn either FAST or BE-FAST—this time through a brief in-person education session. Again, the FAST group retained more knowledge: One month after the session, just over half remembered all of the stroke warning signs they had learned, versus 24 percent of the BE-FAST group. The FAST group also did better when it came to partial recall (remembering at least some of the warning signs) and remembering the face, arm, and speech components, specifically.

It all suggests that, at least for many people, less is more when it comes to learning stroke warning signs.

Time is of the essence

It’s critical that lay people learn and retain knowledge of at least some of the signs of a stroke, since timely treatment can prevent lasting disability or be life-saving. Most strokes are caused by a blood clot that obstructs a blood vessel supplying the brain, and when deprived of oxygen and nutrients, brain cells start to die. Fortunately, there are treatments that can essentially arrest the stroke in progress and limit the brain tissue damage—including “clot-busting” medication and a catheter procedure that removes the blood clot. But to be effective, those treatments must be given within a certain time window after the first indications of a stroke.

So if you or your loved ones aren’t yet familiar with the signs of a stroke, there’s no time like the present. The ASA has some interactive tools designed to help you learn and retain the FAST mnemonic. To get started, here’s more on what each initial stands for:

• Face drooping. Strokes commonly cause one side of the face to droop or twist downward. If you’re unsure, smile or ask the affected person to smile, and the imbalance will likely be clearer.
• Arm weakness. A sudden feeling of weakness or numbness in one arm should grab your attention. Try raising both arms (or ask the affected person to do so) and see if one drifts downward.
• Speech difficulty. Strokes can cause people to suddenly start slurring words and have trouble speaking clearly.
• Time to call 911. If you observe any of the above, in yourself or someone else, call for help immediately, and note the time when the signs first appeared. Don’t worry about getting it “wrong.” The medical professionals will do their job and make the diagnosis, but in the meantime, every minute counts.

A final note: If you already feel confident in your FAST retention and want to delve deeper into stroke warning signs, the National Institute of Neurological Disorders and Stroke is a good resource, along with the ASA. The most important thing is to have a solid understanding of the common ones and know how to respond. You just might save a life, including your own.