# Nine women lost hours of recent memory during or just after Irish sea swims in water as cold as 9.2 C and an Irish hospital series found clear acute scans, full recovery within a day and a repeated pattern suggesting cold-water immersion may trigger transient global amnesia

> Nine women who went sea swimming on the south coast of Ireland between 2019 and 2024 reached hospital with a strikingly specific problem: their ability to form and hold new personal memories suddenly failed during or soon after the swim. A 2025...

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Byline: ARGO.net Editorial Team
Published: 2026-08-09T12:20:02+00:00
Categories: Explainer, Humans

![Adult male swimmer in open water wearing an orange swim cap and goggles, swimming in the sea](https://www.argo.net/wp-content/uploads/2026/08/cold_sea_swimmer.jpg)

Nine women who went sea swimming on the south coast of Ireland between 2019 and 2024 reached hospital with a strikingly specific problem: their ability to form and hold new personal memories suddenly failed during or soon after the swim. A 2025 [European Journal of Case Reports in Internal Medicine series](https://www.ejcrim.com/index.php/EJCRIM/article/view/5200) says the women were 55 to 82 years old, their symptoms lasted from one to seven hours and every patient recovered within 24 hours.

The syndrome was **transient global amnesia**, a short-lived condition in which people stay awake, keep their identity and can still speak or carry out many familiar actions, yet cannot reliably store what is happening around them. In these Irish cases, the central failure was **episodic memory**: the brain stopped laying down the fresh record of where the person was, what had just happened and what had been said a few minutes earlier.

What makes the report worth reading carefully is its narrow claim. The paper does not show how often sea swimming leads to amnesia and it does not prove that cold water directly caused every episode. It documents a repeated clinical pattern in one coastal hospital, with water temperatures from 9.2 C to 18 C and argues that **cold-water immersion** deserves consideration as a possible trigger when a swimmer suddenly becomes repetitive, confused and unable to remember the immediate past.

## What kind of memory failed in these swimmers

**Transient global amnesia**, often shortened to TGA, is defined by a sudden breakdown in new memory formation. The [Cleveland Clinic](https://my.clevelandclinic.org/health/diseases/21028-transient-global-amnesia) notes that people with TGA usually remain alert, know who they are and keep normal language and social skills even while they cannot form new memories. That is why the condition can look so strange to family or friends. The person may appear physically intact while the running record of the day keeps slipping away.

The Irish paper matches that pattern closely. Common features included confusion, short-term memory loss, repetitive questioning and disorientation to time or place. Several women could not recall the swim itself. Others also lost access to events immediately before the water entry. One patient had both **anterograde amnesia**, meaning she could not store new events after the onset and retrograde loss for part of the period around the swim.

What failed was therefore much more specific than a general collapse in thinking. The women were not described as unconscious, paralyzed, or unable to speak. Instead, the disturbance centered on recent experience. One woman kept asking, "What day is it"; another later said she felt "foggy in her head...knew something wasn't right." Those details point straight at the kind of fresh, lived memory that people use to anchor themselves in the immediate moment.

## How the nine episodes unfolded

The cases did not all look identical, yet the rhythm was consistent. Symptoms began during the swim for some patients and immediately after leaving the water for others. One 64-year-old woman became disoriented after only five minutes in the sea. A 55-year-old woman had gone in for just three or four minutes before she began repeating herself. Another patient remembered thinking the water felt especially cold, then later described the rest of the event as "foggy."

Durations ranged widely. One woman's symptoms lasted about an hour, another about 90 minutes, while one patient had roughly seven hours of disrupted memory after the swim. A few were already improving by the time they reached hospital, but the missing block of time remained. In one case, the woman was again oriented by evening yet still could not remember the swim or the CT scan that followed. In another, the patient later described the episode as "like a nightmare."

Each story also shows how **repetitive questioning** becomes the most visible sign to witnesses. Patients asked where they were, how they had arrived, what day it was, or when they had changed into swim gear. A friend noticed one swimmer could not find car keys after the swim. A neighbor found another sitting at a beach in a wet swimsuit with no recollection of getting into the water. The paper reads less like a tale of collapse than of a precise failure to keep experience connected from one minute to the next.

## Why clear scans did not end the evaluation

Every patient in the series had a brain CT scan and three also had MRI. The important common result was the absence of acute findings that could explain a stroke-like emergency. Some scans showed mild chronic changes such as age-related microvascular disease or mild cerebral atrophy, but no patient had an acute lesion that accounted for the episode. That pattern supports the classic description of TGA as a brief, self-limited amnestic event rather than a large destructive brain injury.

Even so, clinicians do not get to assume TGA at the door. The [Mayo Clinic](https://www.mayoclinic.org/diseases-conditions/transient-global-amnesia/diagnosis-treatment/drc-20378535) stresses that stroke, seizure, head injury and other urgent causes of sudden memory loss have to be ruled out first. The [StatPearls review](https://www.ncbi.nlm.nih.gov/books/NBK442001/) similarly notes that diagnosis is clinical only after competing explanations have been excluded. That is why the Irish patients underwent observation, blood work, imaging and in some cases follow-up studies such as carotid ultrasound, echocardiography or telemetry.

This hospital workup matters for a practical reason. Sea swimmers and their companions could be tempted to explain confusion away as cold, fatigue or panic. Acute amnesia still demands medical assessment, because the first appearance can overlap with more dangerous conditions. The case series is useful precisely because it keeps both truths in view: the patients fully recovered and the episode still required urgent evaluation while it was happening.

## Why sea swimming is treated as a possible trigger, not a proven cause

The article's main evidence is repetition. All nine patients were women, all presented to the same coastal hospital, all had sea swimming directly before the event and all met the Hodges and Warlow clinical criteria for TGA according to the authors. Their water exposures covered a temperature range from 9.2 C to 18 C, which means the pattern was not confined to a single extreme winter plunge.

That repeated sequence fits broader clinical descriptions without settling the mechanism. The [Mayo Clinic](https://www.mayoclinic.org/diseases-conditions/transient-global-amnesia/symptoms-causes/syc-20378531) lists sudden immersion in cold or hot water among commonly reported TGA triggers, while also stating that the underlying cause remains unknown. The Irish series therefore sits inside a known trigger pattern, yet it still stops short of proving that cold water by itself produced the memory failure in every case.

Sea entry can place several stresses on the body at once. The [RNLI](https://rnli.org/water-safety/know-the-risks/cold-water-shock) explains that cold water shock rapidly constricts blood vessels, raises heart rate and can make breathing hard to control. That is not the same thing as a proven TGA mechanism and the paper does not claim it is. It simply shows why immersion is biologically abrupt enough to remain a serious suspect when clinicians see the same amnestic pattern cluster around swims.

## What might be happening in the brain

Researchers have debated TGA for decades and the sea-swimming series does not settle the argument. The Irish authors cite ideas involving the **hippocampus**, the brain structure deeply involved in learning and memory and a migraine-like process called cortical spreading depolarization. A [Frontiers in Human Neuroscience review](https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2020.602496/full) describes TGA as a benign memory disorder whose cause is still debated, with stress-linked physiological events potentially disturbing vulnerable memory circuits.

For readers, the simplest way to picture the syndrome is to focus on function rather than anatomy. During an episode, the brain appears able to keep consciousness, language and many practiced behaviors online while failing at the task of filing away the present. That selective breakdown explains why patients can walk, answer simple questions, or travel to hospital and still be unable minutes later to remember the ride or the conversation they just had.

The hippocampus remains central because it helps convert current experience into lasting episodic memory. If that system is briefly disrupted, the person can end up living in a narrow sliding window of awareness. New moments arrive, but they do not stick. The case series cannot show whether cold exposure, stress on circulation, migraine-linked physiology, or some combination opened that window. It can only show that the same memory-centered syndrome followed sea swimming again and again in this group.

## What the case series can support and what it cannot

The strongest supported statement is modest and clinically useful: nine women arrived at one Irish hospital after sea swims with a syndrome centered on sudden recent-memory failure, no focal neurological deficit, no acute imaging changes and complete recovery within 24 hours. That is enough to make physicians in coastal settings more alert to **sea-swimming-associated TGA** when a swimmer starts repeating questions and cannot remember the immediate past.

The paper cannot tell readers the risk of TGA for sea swimmers in general, because it is a **nine-case series** from one hospital rather than a population study. It also cannot show that cold water alone was the decisive cause. The authors themselves use careful language, writing that the series highlights a link and warrants further investigation. That caution is important, because many more people enter cold water without developing transient amnesia and many TGA episodes outside swimming have been tied to other triggers.

Still, the series adds something memorable to the clinical picture of open-water safety. Most warnings around cold seas focus on breathing, exhaustion and drowning. This report keeps **memory disruption** at the center. A swimmer who suddenly seems calm but keeps looping through the same question may be showing a brief failure of episodic memory rather than ordinary post-swim distraction. For relatives, lifeguards and clinicians, that is a signal to seek urgent assessment, document the timing carefully and remember that a full recovery can coexist with a very real loss of the day's personal record.