Who hasn’t struggled occasionally to come up with a desired word or the name of someone near and dear? I was still in my 40s when one day the first name of my stepmother of 30-odd years suddenly escaped me. I had to introduce her to a friend as “Mrs. Brody.”

But for millions of Americans with a neurological condition called mild cognitive impairment, lapses in word-finding and name recall are often common, along with other challenges like remembering appointments, difficulty paying bills or losing one’s train of thought in the middle of a conversation.

Though not as severe as full-blown Alzheimer’s disease or other forms of dementia, mild cognitive impairment is often a portent of these mind-robbing disorders. Dr. Barry Reisberg, professor of psychiatry at New York University School of Medicine, who in 1982 described the seven stages of Alzheimer’s disease, calls the milder disorder Stage 3, a condition of subtle deficits in cognitive function that nonetheless allow most people to live independently and participate in normal activities.

One of Dr. Reisberg’s patients is a typical example. In the two and a half years since her diagnosis of mild cognitive impairment at age 78, the woman learned to use the subway, piloted an airplane for the first time (with an instructor) and continued to enjoy vacations and family visits. But she also paid some of the same bills twice and spends hours shuffling papers.