Doug Whitney, an American man with a genetic predisposition for early-onset Alzheimer’s disease, has successfully avoided the illness, possibly due to accidental heat exposure while working as a mechanic in a ship’s engine room. This incident aligns with emerging research indicating that heat therapy may mitigate Alzheimer’s symptoms.

Whitney’s family carries a genetic variant known as Presenilin 2, inherited from ancestors in a Volga German village dating back to the 18th century. Carriers of this variant typically experience Alzheimer’s symptoms in their late 40s or early 50s.

“My family has been devastated by this disease,” Whitney stated in a press statement. “My mother had 13 siblings, and 10 of them died before they were 60. It was an epidemic.”

Despite having the same mutation, Whitney reached his late 70s without significant memory loss or Alzheimer’s symptoms, making him the only known carrier to escape the condition well beyond the expected onset age.

Jeffrey Kane, a doctor at the French National Center for Scientific Research, became intrigued by Whitney’s case during a conference. He discussed it with Randall Bateman, who has researched Whitney for many years.

At the conference, Kane shared research on hyperthermia’s positive effects on mouse brains. A Finnish study revealed that frequent sauna users are 65% less likely to develop Alzheimer’s disease. Kane and colleague Emmanuel Planel from Université Laval aimed to examine the mechanisms behind this observation.

The results were compelling, especially since Bateman noted Whitney’s extensive work in excessively hot engine rooms of naval vessels for over two decades, beginning at age 18. This led to encouragement from Kane and Planel to further investigate.

In the ship’s engine room, temperatures could soar to 50°C (122°F), and Whitney frequently spent hours inside, sometimes needing to cool down with hoses to prevent overheating.

This prolonged heat exposure likely led to Whitney exhibiting elevated levels of heat shock proteins in his cerebrospinal fluid, which are produced to repair and refold damaged proteins in response to heat.

The increased heat shock proteins might have shielded Whitney from Alzheimer’s development by regulating an essential brain protein called tau, according to Canet. In Alzheimer’s patients, tau proteins misfold and aggregate, correlating with cognitive decline. Imaging studies show that Whitney’s brain contains minimal abnormal tau, explaining his symptom absence. Conversely, his brain is filled with misfolded amyloid proteins, typical in Alzheimer’s, yet symptoms remain unpredictable.

Supporting their findings, Kane and Planel discovered that placing mice in a mini sauna helped maintain the tau protein’s structure and boosted its clearance from the brain. Likewise, tau clearance was found to be enhanced in healthy older adults during wakefulness compared to sleep, likely due to natural increases in body temperature when awake.

Rebecca Nisbet, a researcher at the Florey Brain Research Center in Australia, suggests that Whitney’s work-related heat exposure may contribute to his Alzheimer’s resistance, although genetics likely also play a role. “He may possess protective genes that others in his family do not,” she notes, referencing genes known to influence Alzheimer’s susceptibility.

Nonetheless, Nisbet has started using saunas herself, inspired by evidence indicating their brain health benefits. “I believe this harmless practice can significantly lower dementia risk,” she asserts.

Interestingly, regions with the lowest rates of cognitive impairment and Alzheimer’s disease in individuals over 60 typically experience high temperatures, such as Ballabhgarh, India, and the Bolivian Amazon. “While high temperatures alone aren’t a definitive explanation, they may play a part,” adds Canet.

On the contrary, exposure to cold may elevate Alzheimer’s risk. For instance, tau is known to dysregulate during bear hibernation, according to Nisbet. “The tau in a bear’s brain appears dysfunctional during hibernation but normalizes quickly upon warming,” she explains.

Human studies have also indicated that general anesthesia, which lowers body temperature, can lead to cognitive issues similar to those seen in Alzheimer’s, likely due to its impact on tau. “Caution is necessary in mouse studies since prolonged anesthetic exposure can lead to tau dysregulation,” Nisbett cautions.