New research is suggesting that seriously competing in the Iditarod Trail Sled Dog Race could be bad for your brain.
Sleep deprivation is the 1,000-mile Iditarod’s biggest challenge for human competitors. Asked about the health consequences of this on Tuesday, the lead researcher on the study, Dr. David Holtzman at the Washington University School of Medicine in St. Louis, emailed this response:
“Speculating about this, I would think it could be potentially increasing risk for health later in life but I would think its more likely to be a risk if people do this after the age of 40.”
A tired Mitch Seavey from Sterling was 57 when he became the oldest of Iditarod champions in 2017. Among those helping round out the top-20 that year were Aliy Zirkle, 49; Paul Gebhardt, 60; four-time champ Jeff King, 63; Michelle Phillips, 50; Hans Gatt, 58; Ralph Johannsen, 56; John Baker, 55; and Linwood Fiedler, 65.
Most of them have been involved in long-distance races in which they’ve gone sleepless for decades.
Holtzman cautioned there is no definitive answer to the question of sleep-deprivation and Alzheimer’s, and there have been other studies suggesting a highly active lifestyle offers some protection against the disease.
“Physical activity seems to help your brain not only by keeping the blood flowing but also by increasing chemicals that protect the brain,” writes Dr. Jonathan Graff-Radford at the Mayo Clinic. “Physical activity also tends to counter some of the natural reduction in brain connections that occurs with aging.”
Into the unknown
Brain science is a steadily evolving field of research. It is only recent years, for instance, that scientists recognized the association between repeated concussions and chronic traumatic encephalopathy or CTE as it is more often called.
CTE has been linked to memory loss, difficulty controlling impulsive or erratic behavior, impaired judgment, behavioral disturbances and depression, difficulty with balance, and the gradual onset of dementia.
The disease came to the fore after medical examiner Dr. Bennet Omalu found signs of it in the brain of the late Mike Webster, a center for the Pittsburgh Steelers with a long history of concussions. Webster had three years earlier filed a disability claim with the National Football League Retirement Board claiming football caused his dementia.
“By the time Webster entered the Hall of Fame in July 1997, he had become a recluse, in agony from herniated discs and hand injuries, impoverished and angry at his fate,” Meryl Gordon wrote in Reader’s Digest in 2003. “…His two sons, who lived with him at different times, saw a more tortured side. Colin remembers that his father was shaking so much from his condition that his desperate solution was to buy a police Taser gun. ‘He’d zap himself to calm his nerves. He’d do it 10 or 20 times to relax.'”
The NFL at first fought Omalu’s claims that football was implicated in Webster’s slide into a personal hell, but has since accepted the danger of concussions and established protocols for making sure players are examined after any collision that shows any sign of brain trauma.
The issue is complicated in that some of those who suffer multiple concussions appear immune to CTE in the way the smoker who smokes a pack a day only to die at a ripe old age is immune to lung cancer.
An exhaustive, peer-reviewed examination of all available concussion studies reported in the Journal of Athletic Training in 2017 concluded that “no prospective, longitudinal studies have shown the long-term risks of cognitive decline, neuropsychiatric disorder, or neurodegenerative disease
associated with repetitive sports-related concussion in contact sports. Furthermore, evidence from human studies of the neurologic and neuropsychological effects of repetitive impacts not associated with diagnosed concussion is currently quite limited.”
But the study recognized that concussions, like sleep deprivation, are generally not good for the body. Sleep deprivation has been previously linked to heart disease, heart attack, heart failure, irregular heartbeat, high-blood pressure, stroke and diabetes, and it has long been known for increasing accidents rates.
Researchers studying sleep last year, according to Science magazine, “found that (automobile) drivers who reported fewer than four hours of sleep had 15.1 times the odds of responsibility for car crashes, compared with drivers who slept for the recommended seven to nine hours in the preceding 24-hour period….drivers who reported six, five, and four hours of sleep in the past 24 hours had 1.3, 1.9 and 2.9 times the odds of responsibility for a crash.”
The Iditarod has never paid much attention to the health of its human athletes. The race puts a strong focus on protecting the health of the dogs, but injured mushers have regularly been allowed to continue along the trail.
Competitors themselves scoff at the need for even one doctor along the trail, though there are multiple veterinarians at every checkpoint.
Toughness and the ability to do without sleep have always been considered Iditarod virtues. Whether mushers pay a price for that in later years has never been studied.
Little is known definitively about the causes of Alzheimer’s, either. But if it has anything to do with sleep deprivation, Iditarod mushers would appear prime candidates.
The article was the journal’s effort to ” ‘pop the hood’ of a sled team to examine its engine and on-board diagnostics. We explore the genetics and biochemistry of the dogs’ extreme endurance and learn what happens in the central nervous system when sleep deprivation sets in.”
Most of the story was about the dogs. Sleep-deprivation entered only at the end with a reference to “cat napping” as an aid to surviving long periods without sleep.
“Some race experts speculate that the ability to function under severe sleep deprivation is what separates the Iditarod champions from the middle of the pack. It would be quite interesting to see whether such differences in performance also correlate with less neuronal “catnapping” in the neocortex of the mushers,” the report said.
Whether cat napping would help fend of Alzheimer’s is unclear.
Holtzman and his associates studied both humans and mice looking for chemical changes associated with sleep deprivation. What they found were increases in the protein tau and the amyloid protein. Both have been associated with buildups of plaques thought to play a role in Alzheimer’s.
“Amyloid is important in initiating disease, but the actual damage in the brain is probably due to the accumulation of tau,” Holtzman told the website MedPage Today . “Normally tau protein is inside cells but there is more and more evidence suggesting that its spread to different parts of the brain is responsible for the progression of Alzheimer’s disease.”
Burt Bomhoff, a now retired 82-year-old musher still sharp as a tack, said he found the study “very interesting.”
In an email, he joked that people have “to be insane to get started” in Iditarod to begin with, but having pleaded guilty to insanity he added that he never experienced any symptoms of long-term problems related to sleep deprivation.
Then again, Bomhoff never won the Iditarod. His best finish was 12th in 1984, although there were a number of years in which other mushers thought he had the dogs to contend. The rap on Bomhoff was that he was a “sleeper,” a musher who just couldn’t conquer the sleep-deprivation demands necessary to win.
That aside, Bomhoff said he never noticed much in the way of cognitive decline in the other old mushers he knew and knows, and the professional engineer in him looks for it.
“I still occasionally take an IQ test to see what’s going on,” he confessed, “and work all the puzzles in the news every day for the mental exercise. My IQ is basically what it always was. Don’t know if that’s any measure.”
Maybe, he added, he was just genetically blessed. Three genes have been linked to early on-set Alzheimer’s and one gene has now been linked to a greater chance of suffering late-onset Alzheimer’s, according to the National Institute on Aging.
The connections between genes and environmental influences, such as sleep deprivation, are unclear. Bomhoff said he is convinced “genetics play a role.
“My father lived to be 102 as did his sister. They were still publishing his weekly column in a number of Iowa newspapers when he was 100. He was a Lutheran minister and the columns were faith oriented, lots of Bible stuff that required research.
“Don’t know if that was any measure either. He was a scholar who studied five languages – English, German, Greek, Hebrew and Latin. When he died, some of those references were still in his library.
“The geezers I knew well during Iditarod were close friends like Joe (Redington) and Norman (Vaughan). Both seemed very sharp.”
Both men are long gone. Vaughan, who was already old when he ran his first Iditarod, never really dealt with sleep deprivation. An Alaska legend, he only finished four of the 13 races he started, and his fastest took 21 days and two hours; there was plenty of time to rest.
Redington, one of the founders of the race, was for years a contender. He finished fifth in the 1988 Iditarod at the age of 71. He was a man who slept little and often sitting up. He died of cancer in 1999. He was mentally sharp until the very end, but then almost everyone who met Redington considered him unique.