It took 14 men to restrain José Arcadio Buendía at the height of his delirium, and 20 more to drag and tie him to a chestnut tree. The patriarch of Gabriel García Márquez’s One Hundred Years of Solitude would remain tethered there until his death, “discolored by sun and rain” as he sank into an “abyss of unawareness.”

Decades after the publication of the classic Colombian novel, Francisco Piedrahita came across similar scenes while growing up in the country’s mountainous Antioquia region. Walking through his native hamlet of Canoas, he glimpsed neighbors who seemed disoriented or couldn’t leave their beds. Once, he saw a man tied to furniture with a rope around his waist. “It’s an illness that people get,” Piedrahita’s mother explained, “and you’ll come to understand it one day.”

She was right. Piedrahita watched his grandmother die of it. Other grandparents, aunts, and uncles followed. Piedrahita eventually became a neurology nurse, caring for families, including his own, who were marked by a rare genetic mutation linked to early-onset Alzheimer’s disease.

His story—part clinical, part familial—forms the core of Valley of Forgetting, Jennie Erin Smith’s book on memory, medicine, and hereditary fate in rural Colombia. She follows researchers who, over four decades, have studied the paisa mutation—a gene passed down from a single common ancestor—which causes the illness in nearly everyone who inherits it. In Antioquia, scientists have identified between 1,000 and 1,800 carriers of this particular gene, constituting one of the largest known clusters of familial cases on Earth. Smith, a science journalist, also tells the stories of some members of the 6,000-person clan who participate in research trials, donate loved ones’ brains, and care for one another while bracing for their turn.

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Dementia is one of the modern world’s most dreaded maladies—only in part because we see it more as people live longer. In an era when individual identity and self-expression are often held paramount, the condition threatens to erase the self entirely. Smith’s book is a detailed chronicle of the families and scientists who are drawn together by one mutation, but it isn’t just a grim catalogue of familial illness. Through the characters she speaks with over six years, Smith suggests that forgetting might be more than just an existential loss; it might also be a chance to explore other forms of humanity that are grounded in feeling, presence, or touch.

García Márquez’s 1967 novel follows seven generations of the Buendía family in the fictional Colombian town of Macondo, a place haunted by war and magic. Early in the story, a mysterious plague descends on the town, causing insomnia and erasing memories. García Márquez’s fictional world hovers over Valley of Forgetting, resonating uncannily with Antioquia’s real experience of widespread, precipitous memory loss. A copy of the novel accompanies one woman whom Smith gets to know on a 10-hour bus ride. When clinical trials of an Alzheimer’s treatment called crenezumab launched in Antioquia in 2013, scientists compared it to the magical elixir that ends the amnesiac plague in Macondo. (The crenezumab study was halted in 2022 after disappointing results.)

One Hundred Years of Solitude is a famous work of magical realism. Its timelines collapse and blur, and its characters are bound by ruinous, inescapable fates; the reader cannot avoid disorientation. (García Márquez, who died in 2014 with dementia, once described memory as the material and method of his life’s work: “At bottom, I have written only one book, the same one that circles round and round, and continues on.”)

In Antioquia, many of those connected by the paisa mutation live with a similar sense of distortion. Here, Alzheimer’s is a disease not only of the elderly, but one that can strike adults as early as their 30s. Relatives care for family members while anticipating the day they might need the same help from their younger kin. “Each death caused them to relive the trauma of a previous death, and raised the specter of future ones,” Smith writes. Diagnosis is not an individual experience, but a collective tether. “Looking at the genealogies of these Alzheimer’s clans, the stories ceased to be personal. That level of resolution was lost. The family was the unit,” Smith writes, “its branches growing and shrinking endlessly like fractals.”

Both García Márquez’s and Smith’s stories invite readers to reconsider memory as something relational, inherited, and timeless, rather than strictly personal and chronological. In Antioquia, Smith notes, families carrying the paisa mutation offer scientists a rare opportunity: a known genetic cause of early-onset Alzheimer’s for which they might develop targeted treatments. But that’s not all. The people Smith observed “harbored other types of knowledge” about the disease, she writes, “which they carried, with no formal way to catalogue or transmit it, along with their coveted genes and biomarkers.”

This understanding isn’t clinical, but embodied—what people feel, witness, share, and pass down. When one researcher asked why so many in Antioquia were willing to give their blood, brains, and time to the trials, the answers came fast: “For the kids,” they said. “To break the chain.” Memory is not just what they recall. It’s also how, over generations, people learn to care for one another.

Among ancient European philosophers, cognitive decline in late life was typically seen not as a medical condition but as either an inevitable consequence of aging or punishment for personal faults. (There are communities today where some see dementia more as a symptom of old age rather than a disease, as in Starr Country, Texas.) In some Asian and Middle Eastern traditions, dementia was historically associated with madness or idiocy. Among many First Nations communities, by contrast, memory loss in old age is sometimes embraced as a final flourish of the life cycle: a spiritual stage in which a person draws “closer to the Creator.”

It wasn’t until the turn of the 20th century that scientists—armed with microscopes and techniques that made brain tissue visible at the cellular level—could discern the structure of Alzheimer’s disease: tangled bundles and clumps of misfolded proteins inside and between neurons. But observing the disease under a microscope doesn’t necessarily translate to a full understanding of it.

Antioquia’s families had long viewed dementia not clinically but supernaturally. “The conventional wisdom in Canoas held that it was witchcraft,” Smith writes, “which could mean a lot of things.” A curse from a scorned lover. A punishment cast by a cruel priest. An encounter with the arboloco—the “crazy tree.” “It wasn’t such a stretch to think that someone in a disoriented, nonsensical state was enyerbado, or “under a spell,” she writes; they might be bobo (“stupid”) or necio (“hard-headed”), “but they did not call the person sick.”

Many popular metaphors for dementia suggest erosion: a candle burning down or the body as a shell of the former self it housed. Others conjure a sudden disappearance: fogs, voids, and black holes. Dementia is depicted as an invading enemy, waging war on the mind, a “holocaust of my brain,” as described by the author and activist Thomas DeBaggio in his 2002 memoir, Losing My Mind. These metaphors ultimately reveal—beyond a struggle to confront dementia outright—a terror at the prospect of cognitive dissolution.

The brain is often seen as the engine and archive of a person’s identity. In this light, losing one’s memory is tantamount to losing one’s sense of self. “Life is not what one lived,” García Márquez wrote in the epigraph of his 2002 memoir, “but what one remembers and how one remembers it in order to recount it.” In other words: The survival of one’s selfhood depends on a continued ability to narrate it—to orient yourself in time, space, and plot.

Dementia resists both emotional comprehension and rational explanation; it remains one of medicine’s most stubborn enigmas. Despite billions of dollars in investment and a century-plus of research, scientists don’t yet fully understand what causes it or how to cure it, and it can be challenging to diagnose. Paradoxically, for those who are experiencing dementia, there is only grim certainty: They will die with it. This tension makes the illness ripe for figurative language. “Any important disease whose causality is murky, and for which treatment is ineffectual,” wrote Susan Sontag in her 1978 essay Illness as Metaphor, “tends to be awash in significance.”

In Valley of Forgetting, Smith describes a 25-year-old woman named Daniela who cares for her mother and extended family as early-onset Alzheimer’s moves through their generation—seven of her mother’s 10 siblings were already sick or had died from the disease at the time of Smith’s reporting.

Daniela showered her aunt Mabilia with affection—kisses, ice pops, compliments on her appearance. When her uncle Fredy had only one word left—sí—Daniela recited familiar names for him, his face lighting up with each. As her mother, Doralba, declined, Daniela changed her diapers, rubbed her skin with lotion, and refused to cut her long hair—“a concession,” Smith writes, “to a womanhood she’d worn proudly and which no one wanted to rob her of.”

In Doralba’s final hours, as her breath began to rattle, Daniela massaged her limbs. After her mother died, Daniela cleaned her one last time, smoothing lotion over her skin, as always. “Because to me,” she told Smith, “at that moment, it was as though she was still alive.” She then gave her mother’s body to Neurociencias, the University of Antioquia research lab that had discovered the paisa mutation and has studied those with it for decades.

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The relationship between Daniela and Doralba extends beyond cognition. People with dementia may lose names, dates, recognition of their own face. But as the disease strips one kind of memory, it can deepen others: emotional, sensory. When my grandmother's dementia progressed, she once told me I was her little sister; it wasn’t literally true, of course, but her affection was emotionally honest. As Smith notes in the final pages of her book, each generation of potential paisa mutation carriers has to face the future holding multiple, sometimes opposing, truths: “This was what the families had learned over forty years of taking part in science: to resist undue hope and to resist despair.”

What if people considered a new metaphor for dementia? In neuroscience, the brain is sometimes described as a forest—neurons represent the trees; dendrites (from the ancient Greek for “tree,” dendron) represent the branches. Some writers, like Claude Couturier in her 1999 memoir, Puzzle, Journale d’une Alzheimer, have described living with dementia as being like a tree in autumn that “tries desperately to hold on to its dead leaves, ripped off by a violent wind.”

But fallen leaves don’t have to be a symbol of death. Leaf litter hosts life for hundreds of species: bacteria, ants, mushrooms, shrews. Even bare trees are alive in unseen ways—communicating and sharing nutrients through underground networks of roots and fungi sometimes called “the wood wide web.”

To consider dementia as a tree is to embrace a kind of magical realism: to understand that fresh buds of connection sprout even as older ones fall away, that roots persist, that decay and renewal coexist. As Úrsula, the matriarch of Garcia Márquez’s novel, witnessing her family’s fate repeat itself, exclaims: “I know all of this by heart. It’s as if time had turned around and we were back at the beginning.”

At one point, Daniela reminds Smith that her half-sister and cousin are already in their 30s—the age when Alzheimer’s tends to appear in their family. She, herself, is also approaching 30. Yet Daniela sees not annihilation in her mother’s last days but something profoundly human—beyond memory as people typically understand it.

“She didn’t remember me anymore in her mind. Even as she tried to do it, she couldn’t locate me. But she had me in her soul and in her heart because she could feel me,” Daniela concludes. “Although she couldn’t say it, her eyes could.”