The characters have other motives besides fear to end their lives — guilt, mainly. So why is Alzheimer’s brought into these plots so conspicuously? Perhaps because no other motivation seems as plausible to an audience as a reason to kill oneself.

Despite the prevalence of Alzheimer’s in our national conversation, diagnosing the disease is actually difficult. There is no test that can predict whether forgetting names or words like “bus station” is an indicator of the onset of a degenerative disease. Many older people lose the ability to remember proper nouns but then never progress to losing any other part of speech.

Most forgetfulness is not Alzheimer’s, or dementia, or even necessarily a sign of cognitive impairment. And yet any prophecy about impaired cognition — whether it is fulfilled or not — harms people’s sense of self. They begin to be treated like children, patronized with baby talk or avoided. At the assisted living facility where my mother lived until she died last year at age 96, the nursing director told me that some people think Alzheimer’s is contagious. Victims of misdiagnosis — or, just as devastating, self-diagnosis — dread being shunned, rejected by their offspring, going into debt, becoming a “burden,” losing selfhood.

It needn’t be this way. People with cognitive impairments can live happily with their families for a long time. My mother was troubled by her loss of memories, but she discovered an upside to forgetting. She had forgotten old rancors as well as President George W. Bush’s name. We sang together. She recited her favorite poems and surprised me with new material. We had rich and loving times. Suicide didn’t cross her mind.

The mind is capacious. Much mental and emotional ability can survive mere memory loss, as do other qualities that make us human.

In fact, a revolution in care-giving might be slowly taking root, at least among those aware of alternative narratives of memory loss.

Thomas Kitwood, a British psychologist who was a pioneer in the field of dementia care, died in 1998, but his books, which emphasize personhood instead of debilitation, remain influential. “Making an Exit,” a memoir by Elinor Fuchs, a drama professor at Yale, explored the conversational patterns of her mother when she was in an advanced stage of Alzheimer’s. Anne Basting, director of the Center on Age and Community at the University of Wisconsin, Milwaukee, who wrote a play from poems created by people with Alzheimer’s, has a slogan: “Forget Memory. Try Imagination.”

What a difference it would make if everyone began to share these attitudes. We could make cognition-related fear-mongering shameful and rare, make debates about end-of-life care less searing, improve treatment protocols, reaffirm our collective compact with older people, ease our relationships with people of any age who are cognitively impaired, and enable adults to look forward to getting older with hope instead of despair.