A neurologist reflects on the sense of self and how it can drive survival or live on in memories.

By Dr Crystal Jing Jing Yeo

She was a lively middle-aged woman, a mother and grandmother who loved to cook, garden and laugh. One day, she began to forget things.

She repeated questions, misplaced objects, grew anxious and withdrawn. Within weeks, she started having seizures and jerks. She lost the ability to speak.

Brain imaging showed she had Creutzfeldt-Jakob Disease (CJD), a rare and severe degenerative brain condition caused by an errantly folded protein called a prion.

Now she lies in bed at home, fed through a tube, her eyes wandering without focus. Her husband still talks to her softly, describing the garden she once tended. Sometimes he wonders if it is kinder that she no longer knows what is happening – that her mind, in retreat, has spared her the grief of her own decline.

At the National Neuroscience Institute, many of us care for patients living with severe, disabling conditions. For me, this always raises the same question: Who are we when the brain or body changes?

We spend our lives building who we are – through memories, relationships, work and hopes for the future. Yet, sometimes without warning, something in the brain changes, and all we take for granted begins to slip away.

Each time I see this happen, I find myself asking: What makes us who we are? Is identity rooted in the past we remember, the person we are now, or the future we still hope for?

EXISTING, IN OTHER WAYS

Take CJD, it is cruel and fast, erasing memory and meaning in a matter of months. For loved ones, the grief is not just for a life lost, but for continuity broken.

The woman who once told gently teasing family stories, tended roses with quiet pride, and seasoned soup by instinct, can no longer reach that past. The thread linking her yesterday to her today has snapped.

And yet, she still exists – in the memories of those who love her. She lives in remembered laughter, in fading photos, and in the way her daughter sprinkles salt with the same careless grace to make the most delicious stews.

Her life story has shifted from within her to around her, held now by the devotion of those who love her.

In the movie, Still Alice, when a professor with early-onset Alzheimer’s loses her bearings, her family begins to carry her identity for her. Memories become communal, and the self becomes a legacy.

Perhaps identity is not only what we hold inside, but also what we leave in others – the part of us that persists in their memories, habits and love.

Of course, memories are imperfect. They soften, idealise and omit. Yet perhaps the point is not precision, but presence – the feeling and meaning we leave behind, strong enough to be carried by others when we no longer can.

The lesson is this: We never know when the parts of ourselves we treasure might slip away. Which is why we must try, while we can, to live our values, love deeply, and plant traces of kindness and meaning around us.

FIGHTING FOR LIFE, SOMETHING ENDURES

Patients have also taught me that while the self can be lost, it can also return; and when it does, it brings clarity to what truly matters.

A young man came to us, confused and restless. He had autoimmune encephalitis, a condition in which the body’s immune system attacks the brain, causing inflammation.

He kept saying he needed to go home. He had seizures, became agitated and at times did not know who or where he was.

When he had a moment of lucidity, he would repeat the same plea. His wife was pregnant, he said, and he had to take care of her. His words didn’t always make sense, but the emotion was unmistakable: love, duty, worry.

Autoimmune encephalitis can look like a psychiatric illness, but if recognised and treated, the brain can heal.

For weeks, this young man drifted between clarity and confusion as we treated him with high doses of steroids to calm the immune attack. Then, slowly, he began to return to himself. The angry, inflamed patches in his brain grew quiet.

When I saw him again, he was calm, steady, though slower than before. He showed me a photo of his baby and said quietly: “She’s why I fought to come back.”

Even when his thoughts were scattered, something in him endured. It was love, responsibility, the pull of a future waiting for him. Beneath that chaos was something solid: a husband-to-be and a soon-to-be father who refused to disappear.

As Paul Kalanithi wrote in When Breath Becomes Air after his terminal diagnosis, fatherhood anchored him. He did not fight for a future he would live to see, but for one he hoped to shape for his daughter.

Illness may blur the edges of identity, but it can also sharpen its core. It waits, quietly and fiercely, for whatever matters most to call it back.

MENTALLY ALERT IN A BODY THAT CAN’T MOVE

A third case. He was a quiet elderly man who had lost all movement. Propped up in a wheelchair, a ventilator gently pushing air into his lungs, he communicated through a device that tracked his eyes.

Every breath took effort. Every sentence took time. Yet one message stood out: “I want to live long enough to give my daughter away at her wedding.”

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that affects the motor neurons, the nerve cells that send signals from the brain to the muscles. The mind remains clear, but the body gradually loses all ability to move.

At first, it might be subtle: a weak grip, a stumble, slurred speech. Eventually, even swallowing, breathing and smiling become impossible.

My patient lived to see his daughter walk down the aisle. On that day, from his wheelchair at the end of the aisle, he smiled as she passed by. His family said it was the happiest moment of his life. He died a few months later, his mind as sharp as ever.

His story echoed that of French writer Jean-Dominique Bauby in his memoir The Diving Bell And The Butterfly. After a brain-stem stroke left him able to blink only one eye, Bauby wrote his memoir blink by blink. The body can be the diving bell, heavy and unresponsive, but imagination can remain the butterfly.

Even the co-director of Still Alice lived this truth. He made the movie while battling ALS and died shortly after its release.

In ALS, the body fails first, but the person endures. My patient’s humour, love and will remained untouched. Medicine cannot always give more years, but we try to help our patients find more living in the time that remains.

And perhaps there is a deeper lesson here. That the inherent dignity of a human being does not rest in movement, speech or physical strength. A still body is not an empty one. Someone who cannot speak is not silent and simply needs a way to be heard. To treat the disease without seeing the person is to miss the point entirely.

The Prayer of Jabez speaks of borders expanding. Illness may shrink the borders of the brain and body, as memory fades and movement falls away. Yet time and time again, I see something else widen: purpose, clarity and courage. When the physical world narrows, the will to live, to love, to strive, and to achieve, not merely endure, may expand beyond measure.

WHAT IS THE SELF?

From these stories, a pattern emerges.

In CJD, identity shifts outwards, carried by those who love us when we can no longer carry ourselves.

In autoimmune encephalitis, identity can flicker and return, tethered by purpose and connection.

In ALS, identity persists in thought and imagination, even as the body yields.

Identity is not fixed, but bends to circumstance. It is more than memory or autonomy. It is not only the past we remember, or the present we live in, or the future we imagine. It is the thread that runs through them all.

We are tapestries woven from love, purpose and relationship. When illness pulls one strand loose, like a cat’s cradle, the other strands can hold the shape for a while. We are not just our neurons, we are all the hands that have touched the string.

These illnesses strike without warning, reminding us how fragile our bodies and minds are. But they also reveal something enduring. Even when the brain fails, even when the body stops moving, something essential remains. And from these lives, lessons emerge.

Live deliberately. We cannot choose when our threads may fray, but we can choose the pattern we weave.

See the person, not the disease. A still body isnot empty, and a quiet mind still holds purpose.

Invest in relationships. When memory fades, it is love and community that carry identity forward.

To be human is to exist in two places at once: within ourselves, and within those who remember us. Meaning does not disappear with speech or strength. It is found in the tenderness of those who stay, and in the quiet recognition that the person is still there, even when they can no longer say so.

In the end, perhaps to be human is simply this: to be remembered, held, and loved, even as the body or mind lets go.

Dr Crystal Jing Jing Yeo is a consultant in neurology, focusing on neuromuscular and electrodiagnostic medicine, at the National Neuroscience Institute.

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