I’m struck by the difference between losing my dad to cancer and my mother — still living — to Alzheimer’s.

The Other Side of Grief is a series about the life-changing power of loss. These powerful first-person stories explore the many reasons and ways we experience grief and navigate a new normal.

Dad was 63 when he was told he had non-small cell lung cancer. Nobody saw it coming.

He was fit and healthy, a nonsmoking ex-Marine gym rat who bordered on vegetarianism. I spent a week in disbelief, pleading with the universe to spare him.

Mom hasn’t been formally diagnosed with Alzheimer’s disease, but the symptoms showed up in her early 60s. We all saw it coming. Her mom had early-onset Alzheimer’s and lived with it for nearly 10 years before she passed away.

There’s no easy way to lose a parent, but I’m struck by the difference between the loss of my dad and that of my mother.

The ambiguity of Mom’s illness, the unpredictability of her symptoms and mood, and the fact that her body is fine but she’s lost much or her memory is uniquely painful.

I sat with Dad in the hospital after he had surgery to remove parts of his lungs teeming with cancerous cells. Drainage tubes and metal stitches wound their way from his chest to his back. He was exhausted but hopeful. Surely his healthy lifestyle would mean a quick recovery, he’d hoped.

I wanted to assume the best, but I’d never seen Dad like this — pale and tethered. I’d always known him to be moving, doing, purposeful. I desperately wanted this to be a single frightening episode that we could recall gratefully in the years to come.

I left town before the biopsy results came back, but when he called to say he’d need chemo and radiation, he sounded optimistic. I felt hollowed out, scared to the point of trembling.

Over the next 12 months, Dad recovered from chemo and radiation and then took a sharp turn. X-rays and MRIs confirmed the worst: The cancer had spread to his bones and brain.

He called me once a week with new treatment ideas. Maybe the “pen” that targeted tumors without killing surrounding tissue would work for him. Or an experimental treatment center in Mexico that used apricot kernels and enemas could banish the deadly cells. We both knew this was the beginning of the end.

Dad and I read a book on grief together, emailed or talked every single day, reminiscing and apologizing for past hurts.

I cried a lot during those weeks and I didn’t sleep much. I wasn’t even 40. I couldn’t be losing my Dad. We were supposed to have so many years left together.

When Mom started slipping, I immediately thought I knew what was happening. At least more than I knew with Dad.

This confident, detail-oriented woman was losing words, repeating herself, and acting unsure much of the time.

I pushed her husband to take her to the doctor. He thought she was fine — just tired. He swore it wasn’t Alzheimer’s.

I don’t blame him. Neither of them wanted to imagine that this was what was happening to Mom. They’d both seen a parent gradually slip away. They knew how awful it was.

For the last seven years, Mom has slid farther and farther into herself like a boot into quicksand. Or, rather, slow-sand.

Sometimes, the changes are so gradual and imperceptible, but since I live in another state and only see her every few months, they loom large for me.

Four years ago, she left her job in real estate after struggling to keep the details of particular deals or regulations straight.

I was angry that she wouldn’t get tested, annoyed when she pretended not to notice how much she was slipping. But mostly, I felt helpless.

There wasn’t anything I could do besides call her every day to chat and encourage her to get out and do things with friends. I was connecting with her like I had with Dad, except we weren’t being honest about what was going on.

Soon, I began to wonder if she really knew who I was when I called. She was eager to talk, but couldn’t always follow the thread. She was confused when I peppered the conversation with my daughters’ names. Who were they and why was I telling her about them?

On my next visit things were even worse. She was lost in the town she’d known like the back of her hand. Being in a restaurant was panic-inducing. She introduced me to people as her sister or her mother.

It’s shocking how empty it felt that she didn’t know me as her daughter anymore. I had known this was coming, but it hit me hard. How does that happen, that you forget your own child?

As painful as it was to watch my father waste away, I knew what he was up against.

There were scans, films we could hold up to the light, blood markers. I knew what chemo and radiation would do — what he’d look and feel like. I asked where it hurt, what I could do to make it a little better. I massaged lotion into his arms when his skin burned from the radiation, rubbed his calves when they were sore.

When the end came, I sat by his side as he lay in a hospital bed in the family room. He couldn’t talk because of a massive tumor blocking his throat, so he squeezed my hands hard when it was time for more morphine.

We sat together, our shared history between us, and when he couldn’t go on any longer, I leaned in, cradled his head in my hands, and whispered, “It’s OK, Pop. You can go now. We’ll be OK. You don’t have to hurt anymore.” He turned his head to look at me and nod, took one last long, rattling breath, and went still.

It was the hardest and most beautiful moment of my life, knowing he trusted me to hold him as he died. Seven years later, I still get a lump in my throat when I think about it.

In contrast, Mom’s blood work is fine. There’s nothing in her brain scan that explains her confusion or what makes her words come out in the wrong order or stick in her throat. I never know what I’ll encounter when I visit her.

She’s lost so many pieces of herself at this point that it’s hard to know what’s there. She can’t work or drive or talk on the phone. She can’t understand the plot of a novel or type on the computer or play piano. She sleeps 20 hours a day and spends the rest of the time staring out the window.

When I visit she’s kind, but she doesn’t know me at all. Is she there? Am I? Being forgotten by my own mother is the loneliest thing I’ve ever experienced.

I knew that I would lose Dad to cancer. I could predict with some accuracy how and when it would happen. I had time to mourn the losses that came in fairly rapid succession. But most importantly, he knew who I was until the last millisecond. We had a shared history and my place in it was firm in both our minds. The relationship was there just as long as he was.

Losing Mom has been such an odd peeling away, and it could last for many years to come.

Mom’s body is healthy and strong. We don’t know what will eventually kill her or when. When I visit, I recognize her hands, her smile, her shape.

But it’s a bit like loving someone through a two-way mirror. I can see her but she doesn’t really see me. For years, I’ve been the sole keeper of the history of my relationship with Mom.

When Dad was dying, we consoled each other and acknowledged our mutual pain. As excruciating as it was, we were in it together and there was some comfort in that.

Mom and I are each trapped in our own world without anything to bridge the divide. How do I mourn the loss of someone who’s still physically here?

I sometimes fantasize that there will be one lucid moment when she looks into my eyes and knows exactly who I am, where she inhabits one more second of being my Mom, just like Dad did in that last second we shared together.

As I grieve the years of connection with Mom that’ve been lost to Alzheimer’s, only time will tell whether or not we get that final moment of recognition together.

Are you or do you know someone caring for someone with Alzheimer’s? Find helpful info from the Alzheimer’s Association here.

Want to read more stories from people navigating complicated, unexpected, and sometimes taboo moments of grief? Check out the full series here.

Kari O’Driscoll is a writer and mother of two whose work has appeared in outlets such as Ms. Magazine, Motherly, GrokNation, and The Feminist Wire. She has also written for anthologies on reproductive rights, parenting, and cancer and recently completed a memoir. She lives in the Pacific Northwest with two daughters, two puppies, and a geriatric cat.