My mom’s friend Edie told me to stop posting pictures of my mom blank-eyed with her mouth hanging open, and I see her point. As a younger woman, my mom would have been horrified to look demented. But this is who she is now, not exactly herself and yet always the same.

The way she looks is how the people we hire present her: clean, combed and dressed. Some of her caregivers take a swipe at her mouth with lipstick. At a glance, she does not seem like someone who cannot brush her own teeth and has ceased to concern herself with matters of self-maintenance.

My mother isn’t on a life-support machine, but she is certainly on life support. Food is procured and prepared for her. She is spoon-fed and often must be cajoled to open her mouth, reminded to swallow. She is hoisted from bed to wheelchair and back. Absent the rails on her bed, she would have fallen to the floor many times by now.

She is gentle. She speaks, even though we mostly can’t make out the words. Her eyes sometimes snag on mine. She smiles when I greet her with my lifelong, “Ola Momba.”

Not long ago, she thought she was in a prison, a concentration camp, being held hostage by bad guys who’d tricked my brother and me into trusting them. She used to worry. Luckily her waking nightmares are mostly controlled with meds now, and her delusions seem pleasant.

Sometimes she appears to revisit earlier chapters in her life. She calls to my dead father to clarify a point, exactly as she used to call to him in the next room, and she is apparently satisfied by his responses. Sometimes she’s back with her Yiddish chorus singing “Rozhinkes mit Mandlen.” Sometimes she seems to see me as child, which means she’s been transported to the ’60s. Nice for her.

As a mother myself, I know that each phase of my children’s development irretrievably replaced the one before. The toddler eclipsed the newborn. The grade-schooler morphed into a teen. Each of their consecutive selves was distinct and beloved. Those children are grown up and gone forever, but the through-lines of my kids’ essential personalities continue unbroken. Who they are now is who they were at birth and in all their variations since.

Just as I will never again see my kids as they once were, I will never again see my mom as she once was. There are times I feel the loss so sharply I can barely breathe, but even now, when she is 91 with Parkinson’s dementia, my Momba’s through-line glimmers on.

She still responds to my embrace and the sound of my voice. Even if she’s not always sure who I am, I get the impression that she knows I am dear to her, that I pose no threat, and may even be a source of comfort and safety.

Many people get mean and angry with dementia, and who can blame them? Waking daily in an eternally unfamiliar place, being handled by strangers you never come to recognize. For those who idolize “living in the present,” I offer my mother’s terrifying existence as proof that we need a past and a future too.

But my mom isn’t angry, at least not yet. She is courageous, stoic. That’s how it seems to me.

I check the obits these days, and I wonder how people select their photos. A man who died at 86 is memorialized at 19 in his Korean War uniform or in his high school graduation picture. Even if the image represents his peak, his finest hour, it makes little more sense than posting his baby picture. I think a sequence would be better, a flip book of changes.

I recently learned that when caterpillars exit the larva stage, they knock off their own heads and feet, encase themselves in a cocoon, and turn to goo. They don’t just grow butterfly wings out of their existing bodies, they liquefy and get reassembled. Metamorphosis gives me comfort, even if it is gross.

I tell myself and my mom’s friend Edie that Momba the chrysalis is as much herself as when she was a caterpillar. We are alive until we are not. We are ourselves until we cease to exist.

Meanwhile, I can hold and rock this woman who once rocked me. I can wipe away her drool, as she once wiped mine. She is not as she was. She is not my mother as I remember her, but she’ll always be my mom.