So-called transient ischemic attacks can eventually lead to cognitive declines as steep as those following a full-on stroke, new research finds.

Kristin Kramer woke up early on a Tuesday morning 10 years ago because one of her dogs needed to go out. Then, a couple of odd things happened.

When she tried to call her other dog, “I couldn’t speak,” she said. As she walked downstairs to let them into the yard, “I noticed that my right hand wasn’t working.”

But she went back to bed, “which was totally stupid,” said Ms. Kramer, now 54, an office manager in Muncie, Ind. “It didn’t register that something major was happening,” especially because, reawakening an hour later, “I was perfectly fine.”

So she “just kind of blew it off” and went to work.

It’s a common response to the neurological symptoms that signal a T.I.A., a transient ischemic attack or ministroke. At least 240,000 Americans experience one each year, with the incidence increasing sharply with age.

Because the symptoms disappear quickly, usually within minutes, people don’t seek immediate treatment, putting them at high risk for a bigger stroke.

Ms. Kramer felt some arm tingling over the next couple of days and saw her doctor, who found nothing alarming on a CT scan. But then she started “jumbling” her words and finally had a relative drive her to an emergency room.