Alzheimer’s: the disease that erodes time itself

The team focused on microglia and astrocytes, the guardians tasked with removing debris, eliminating dead cells, and disposing of toxic proteins, chief among them amyloid, the hallmark of Alzheimer's. These cells typically operate according to a precise biological rhythm, activating at set times to preserve the brain's health.

To understand the impact of the disease on this rhythm, researchers analysed gene expression patterns in healthy mice and in those burdened with amyloid deposits over a full 24-hour cycle, collecting samples every two hours. The results were striking. Hundreds of genes that normally followed a consistent temporal pattern had lost their rhythm entirely. Genetic sequences that should have pulsed with regularity became scattered and unsynchronised, leading to a marked decline in the cells' capacity to cleanse the brain and remove amyloid. In other words, amyloid accumulation is not merely the result of increased production, but of cells stripped of their natural timing and unable to perform their cleansing work when it is needed.

Restoring the daily rhythm

What is most astonishing is that the disruption does not simply dismantle the familiar cadence of the day; it generates strange, unnatural rhythms in hundreds of genes that normally lie beyond the reach of the biological clock. Most of these aberrant patterns are linked to inflammation, indicating that Alzheimer's transforms cells from guardians of maintenance and repair into agents of irritation and decline.

This discovery reframes one of the central mysteries of the illness: why does the disturbance of sleep and wakefulness accelerate its progression? Because the disruption unfolds not only in the patient's psyche and behaviour, but within the very mechanisms through which the brain cleanses and sustains itself.

Lead researcher Erik Musiek, a professor of neurology at Washington University School of Medicine, notes that the daily rhythm plays a far broader role than previously imagined. Eighty-two genes are known to be associated with Alzheimer's risk, and nearly half of them are governed by the circadian clock. Once that rhythm falls out of sync, these disease-linked genes begin to drift, hastening amyloid accumulation and intensifying the symptoms of decline.

These findings open a new therapeutic horizon. Alzheimer's can no longer be viewed solely as a condition requiring the removal of amyloid or the protection of neurons. It must also be understood as a disorder that demands the recalibration of the biological clock within the brain's supporting cells. Scientists now propose new treatment pathways: strengthening or suppressing the daily rhythm in specific cell types, halting harmful rhythms in others, or developing medicines that target genetic cycles directly rather than the toxic proteins they produce.

Musiek describes the ultimate aim as "learning how to improve the daily rhythm in order to prevent amyloid accumulation and diminish the manifestations of disease." Should these strategies succeed, mastery of biological time may become one of the most promising avenues for slowing or even delaying the advance of Alzheimer's.

Alzheimer's infiltrates the brain not merely as a thief of memory, but as a force that ravages time itself. The daily rhythm, that inner pulse governing sleep, wakefulness and the storage of recollections, falls into disarray as the illness progresses. The body loses its biological compass, and time begins to collapse from within.

When the brain's temporal command centre fails, night and day grow indistinguishable. The patient may sleep at odd hours, awaken suddenly in the middle of the night, and confront daylight in a state of exhaustion and confusion. This disorder undermines more than routine; it strikes at the core of memory. New experiences are normally secured during deep nocturnal sleep, but when sleep is fragmented, the brain loses its capacity to anchor events. Daily life fades as though it never occurred.

The theft of memory's present

Wakefulness, once the domain of focus and attention, becomes fractured, marked by episodes of confusion and mental drift. A single day splinters into unstable intervals of awareness and bewilderment, until time itself dissolves into scattered fragments rather than a continuous stream.

Alzheimer's, therefore, does not merely steal the past; it corrupts the present. The timing of everything—sleep, attention, memory, the sense of the day—falls into chaos. The patient becomes trapped in a world without rhythm or a reliable sense of time. As the daily rhythm deteriorates, cognitive function erodes ever more rapidly, creating a vicious cycle that makes the disease both more aggressive and harder to manage.

The disorder of time does not stop at the boundaries of body and brain; it collides with the external world. Humanity lives by a social clock—work schedules, visits, prayers, family rituals, communal occasions. When the inner rhythm collapses, the patient loses the ability to inhabit this shared time, and social separation begins, often imperceptibly.

Even the simplest appointments become formidable challenges: attending a family lunch, meeting friends, taking a walk, or following the evening routine at home. Disturbed sleep leaves the patient alert while others rest, and drowsy while others are active. A temporal mismatch emerges, akin to jet lag, but without travel or the hope of return.

As recognition of people, places, and events fades, the social fabric of time unravels. Relationships depend on shared memory—faces, conversations, experiences. As memory erodes, bonds weaken. With each forgotten name or vanished moment, isolation deepens and the emotional burden on families grows heavier.

Eventually, the patient ceases to participate in the family's chronology, inhabiting instead a parallel time that no one else can enter. Nights stretch long without rest, days shrink into haze, and social encounters become exhausting and incomprehensible. The gulf widens between two worlds: one living in the present, and one whose sense of time is disintegrating from within.

This separation is not a mere side effect; it is a force that accelerates decline. Isolation reduces cognitive stimulation, hastens memory loss and further erodes temporal awareness. Thus, both patient and family are drawn into a double tragedy: an inner time in disarray, and a social time that can no longer be sustained.

Yet despite this bleak portrait, research suggests the daily rhythm is not entirely lost. It remains a system that—to varying degrees—can be reorganised and restored. Modern therapy no longer concentrates solely on memory; it seeks to reset the inner clock so the brain might once again distinguish night from day, sleep from wakefulness, and clarity from confusion.

Resetting inner time

The first and most powerful element in restoring inner time is light. The retina does more than perceive images; it transmits light to the brain's biological clock, regulating sleep, hormones, and alertness. Light therapy has therefore become a cornerstone in treating Alzheimer's. Morning exposure to bright light, followed by softer lighting in the evening, reduces night-time disturbances and provides the brain with clear temporal cues that help re-establish its daily cycle.

The second element is movement and physical activity. Gentle exercise or a daily walk at a fixed hour acts as a strong synchroniser. The brain begins to associate daytime motion with energy and wakefulness, reinforcing its internal rhythm and encouraging deeper, more restorative sleep. Physical activity also increases blood flow to memory-related regions, helping to stabilise cognitive function.

Social routines follow close behind: meals at consistent hours, family gatherings held at predictable times, and daily activities repeated with calm regularity. This steady structure gives the patient temporal landmarks, easing confusion and softening the isolation imposed by a collapsing social clock.

Science is now advancing towards pharmaceutical and genetic therapies that target the biological clock directly. These include drugs that adjust melatonin levels, proteins that modulate circadian gene activity, and emerging technologies that may resynchronise the inner clock with the external world. Clinical studies already suggest that strengthening circadian rhythm can slow memory decline, indicating that time is not merely a symptom of the disease but a pathway into its treatment.

Resetting inner time does not cure Alzheimer's, but it returns to the patient fragments of coherence and humanity: steadier sleep, clearer wakefulness, less fragile memory, and a social life less burdened by disconnection. It is an attempt to rescue the patient from broken time and return them, even partially, to a rhythm that resonates with those they love.

Safeguarding time

At its core, Alzheimer's reveals not only the limits of medicine but the limits of human existence. Memory is not a simple storehouse of facts; it is the fabric of personal time, the thread that keeps identity intact across a lifetime. It bears witness to childhood, friendship, love, loss, and the experiences that shape us. When that fabric frays, the meaning of life begins to unravel.

This is why scientific research now seeks not only a cure, but the preservation of human time itself. Every advance in understanding sleep and wakefulness, every attempt to restore circadian harmony, every intervention that grants a patient a few moments of clarity or the recognition of a face or a word, is more than a medical achievement—it is a defence of human presence in the world.

The near future may not deliver a complete cure for Alzheimer's, but science continues to move toward a greater goal: that patients may live as long as possible in a moment they can recognise, in a day that resembles the ones they once knew, in relationships that do not vanish too quickly into fog.

Safeguarding time is not a luxury. It is the foundation of human dignity. For human beings do not live by heartbeat alone, but by the history they carry within. In the end, hope endures that science will succeed, sooner or later, not only in slowing the disease but in protecting the thread that binds us to ourselves and to those we love. If humanity can preserve time from decay, then in a profound way, it preserves itself.