Health News

In the year and a half following the Supreme Court Dobbs decision that revoked the federal right to an abortion, hundreds more infants died than expected in the United States, new research shows. The vast majority of those infants had congenital anomalies, or birth defects.

Earlier research found that infant mortality spiked in Texas after a 6-week abortion ban took effect in 2021, and experts say the new data suggests that the impacts of the bans and restrictions enacted by some states post-Dobbs have been large enough to affect broader trends.

“This is evidence of a national ripple effect, regardless of state-level status,” said Dr. Parvati Singh, an assistant professor of epidemiology with The Ohio State University College of Public Health and lead author of the new study.

In the new paper, published Monday in JAMA Pediatrics, Singh and co-author Dr. Maria Gallo, a professor of epidemiology and associate dean of research with the Ohio State University College of Public Health, compared infant mortality rates for the 18 months following the Dobbs decision against historical trends.

They found that infant mortality was higher than usual in the US in several months after the Dobbs decision and never dropped to rates that were lower than expected.

In the months that infant mortality was higher than expected – October 2022, March 2023 and April 2023 – rates were about 7% higher than typical, leading to an average of 247 more infant deaths in each of those months.

About 80% of those additional infant deaths could be attributed to congenital anomalies, which were higher than expected in six of the 18 months following the Dobbs decision, according to the new research. Congenital anomalies can range from mild to severe cases, and some of the most common types can affect an infant’s heart or spine. In some cases, babies with a birth defect may only survive a few months.

“This is the tip of the iceberg,” Singh said. “Mortality is the ultimate outcome of any health condition. This is a very, very acute indicator. It could be representative of underlying morbidity and underlying hardship.”

Other research has found that births have increased in states with abortion bans, and experts say that some of that increase is linked to a disproportionate rise in the number of women who are carrying fetuses with lethal congenital anomalies to term.

“Whether the pregnancy was wanted or unwanted, we know that many of these are pregnancies that would have ended in abortion had people had access to those services,” said Dr. Ushma Upadhyay, an associate professor in the department of obstetrics, gynecology and reproductive science at the University of California, San Francisco. She was not involved in the new study, but does research abortion trends in the US.

Experts say that abortion bans can also affect access to broader health care, which can lead to increased risk for both babies and mothers.

“The well-being of a pregnant person is inextricably linked to the well-being of the pregnancy,” Upadhyay said. Abortion bans may affect access to and willingness to seek prenatal care and broader support systems, she said, and the barriers compound.

“People who face the most structural barriers in terms of poverty, lower levels of education, food insecurity, and other life stressors can’t access abortion care, and these factors also increase their risks of poor pregnancy and birth outcomes,” she said.

Infant mortality includes deaths that occur before a baby has turned one, so it is difficult to parse out exactly what was happening during the months that did see rates that were higher than expected, Singh said. But the timing – four, nine and 10 months after the Dobbs decision – line up with about the time that congenital anomalies can be identified in the fetus and a full-length gestation term.

“These studies are providing a signal that people aren’t getting the care that they need, and because of that, there are spillover effects,” said Dr. Alison Gemmill, a demographer and perinatal epidemiologist at Johns Hopkins University who led the research identifying the link between rising infant mortality and abortion restrictions in Texas. “It’s never going to be the case that everybody’s going to be able to overcome the barriers of these bans.”

A recall of ready-to-eat meat and poultry items made by BrucePac has been expanded to include nearly 1.8 million pounds of additional products, for a total of more than 11.7 million pounds of products recalled over possible listeria contamination, the US Department of Agriculture’s Food Safety and Inspection Service says.

The products were distributed to restaurants and institutions nationwide, including ready-to-eat items that are “on store shelves or in consumers’ refrigerators or freezers,” the agency says. It has released a preliminary list of schools that received the products in Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, New Jersey, New York, Ohio, Pennsylvania, Tennessee, West Virginia, Wisconsin and the District of Columbia.

The Food Safety and Inspection Service discovered the issue during routine product testing of finished poultry products, the agency said. BrucePac ready-to-eat chicken was identified as the source of the listeria bacteria, which may have affected other ready-to-eat meat and poultry items that were produced in Durant, Oklahoma, from May 31 to October 8.

Listeria causes listeriosis, the third leading cause of death from foodborne illness in the United States. Symptoms can include fever, muscle aches and fatigue. An infection can also cause a stiff neck, a headache, confusion or seizures. Those most at-risk for severe outcomes are older adults, pregnant women and people with weakened immune systems.

There have been no confirmed reports of illness related to the products, but some people who get sick recover without being tested for listeria, and it usually takes weeks to link an illness to an outbreak.

“We are committed to providing safe, high-quality products,” BrucePac says. “We are working closely with the USDA to ensure that all necessary actions are taken to ensure a safe food supply. We will not resume production until we are confident the issue has been resolved.”

The Food Safety and Inspection Service says it is continuing to gather information about the issue. Anyone with questions about the recall can contact BrucePac at 503-874-3000. Consumers who have questions about food safety can call the USDA at 888-674-6854.

This recall follows a deadly listeria outbreak connected to recalled Boar’s Head deli meat that is the nation’s largest in more than a decade. There have been 59 hospitalizations and 10 deaths since the US Centers for Disease Control and Prevention started an investigation in July.

Whooping cough cases are continuing to rise in the United States, with new data from the US Centers for Disease Control and Prevention showing that there are five times as many cases this year than at this point last year.

The data, updated Thursday, shows the case count at 18,506 as of the week ending October 12. At the same time last year, 3,382 cases had been reported.

Whooping cough, also known as pertussis, is a common respiratory illness in the US. It may be difficult to identify because its symptoms are so similar to those of other respiratory bacteria and viruses, which often circulate at the same time as whooping cough.

The infection starts with symptoms like a runny nose, a low-grade fever and a tickly cough. A week or two later, it moves into a new stage, leading to a violent full-body cough.

These coughing fits can be so severe that they cause patients to vomit or break ribs, and they’re often accompanied by a whooping sound as the person tries to catch their breath.

Antibiotics can treat the infection, but only if it’s caught within the first few weeks, before the arrival of the exhausting, painful cough. Then, the only treatment is comfort care with plenty of rest and fluids while the infection runs its course.

While whooping cough can be serious for all ages, children younger than 1 are particularly sensitive because their immune systems are still developing. This is especially true for infants and young children who haven’t had all their recommended vaccines.

Some babies don’t develop a cough and instead struggle to breathe. Infants who haven’t been fully vaccinated are more likely to develop serious complications such as pneumonia and, in rare cases, encephalopathy.

Whooping cough spreads through bacteria transmitted through the air. The infection is most commonly spread at schools, child care centers and hospitals.

Many people can be contagious up to two weeks after coughing. This is how many children get infected by older siblings, parents or other caregivers who may not know that they’re infected.

The best way to prevent or minimize the symptoms of whooping cough is to get yourself and your child vaccinated. The CDC recommends that children get the DTaP vaccine and adolescents and adults get the TDaP vaccine.

Florida has seen a recent increase in confirmed cases of flesh-eating bacteria following the devastating hurricanes Helene and Milton, according to state health department data.

The Tampa Bay-area counties of Hillsborough and Pinellas – which were inundated by torrential rain and a devastating storm surge – saw the largest increase of the bacteria Vibrio vulnificus commonly found in warm coastal waters, but concentration levels can rise with heavy rain or flooding. Before Hurricane Helene made landfall on September 26, there were no reported cases in Pinellas County and one in Hillsborough County. Now, Pinellas has 13 confirmed cases, and there are seven in Hillsborough.

Florida had six confirmed cases of Vibrio vulnificus in September before Hurricane Helene’s arrival but the number rose to 24 by the end of the month. There have been 38 confirmed cases since the hurricanes struck, bringing the total to 76 this year.

People can become infected by Vibrio vulnificus by ingesting or exposing open wounds to contaminated water or by eating improperly cooked seafood. Those with compromised immune systems, liver disease or and open wounds are at higher risk of Vibrio vulnificus infection.

Of the 150 to 200 Vibrio vulnificus cases reported to the US Centers for Disease Control and Prevention every year, about one in five people die from the infection, sometimes within one or two days of getting sick.

The Florida Department of Health issued a statement last week, ahead of Milton’s landfall, urging residents to remain vigilant and avoid floodwaters where Vibrio bacteria can multiply rapidly.

The agency recommends people avoid swimming or wading in floodwaters. If someone must come into contact with potentially contaminated water, they should cover any wounds with a waterproof bandage and wash thoroughly afterward.

One Sunday night in February, Will Shortz was at his desk at home in Pleasantville, New York, when he leaned to his left and realized he couldn’t sit back up straight.

The stroke was on the right side of his brain, leaving the left side of his body “completely incapacitated” and causing his speech to be slurred, said Shortz, 72.

It didn’t affect his ability to solve and make puzzles, he said – a gift for the millions of people who enjoy his work as the crossword editor of the New York Times and the puzzlemaster of NPR’s “Weekend Edition Sunday,” roles he’s held for decades.

Strokes are caused when a blood clot blocks blood flow to the brain or, less frequently, when a blood vessel ruptures and causes bleeding in the brain. Almost 800,000 people in the United States are estimated to have a stroke each year, according to the US Centers for Disease Control and Prevention, and more than 165,000 die from stroke, making it one of the country’s leading causes of death.

Patients can recover, even fully, with the help of months of rehabilitation work.

Getting help fast

That evening in February, Shortz knew that he needed to get emergency treatment quickly. But because it was winter and he was dressed for a game of table tennis – another of what he calls his “obsessions” – he decided to change into warmer clothes and use the bathroom before going to the hospital.

It was there that he “crumpled to the floor,” he said. Without his phone and unable to get back up or even to crawl, Shortz began to worry. Somehow, though, he said he was able to “squirm like a worm on my back” into his office to get his phone and call his partner, who came immediately and called an ambulance.

Even with the 15 minutes he spent on the floor, Shortz said, he was at the hospital within an hour. Such quick care, stroke experts emphasize, is crucial.

“Time is brain,” said Dr. Michelle Lin, a neurologist at Mayo Clinic Hospital in Jacksonville, Florida. “For every single minute that there’s a delay in presenting to a doctor’s office or emergency room, about 2 million neurons die.”

Lin said she recommends that people who suspect they’ve had a stroke call 911 for an ambulance to get emergency care as fast as possible.

One way to recognize stroke symptoms, she said, is to use the mnemonic device B.E. F.A.S.T. It stands for:

If people notice changes in balance or vision, weakness or numbness in their face or arms, or trouble with speech, it’s important to seek emergency care in as short a time as possible, Lin emphasized.

Shortz’s initial treatment

Shortz said he spent more than a week in emergency care at the hospital, where staffers got him on his feet “as quickly as they could.” From there, he spent several weeks in a rehabilitation center doing both occupational and physical therapy before moving to a “subacute” facility for a month. There, he did 2½ to three hours of therapy every day.

“That’s the kind of physical therapy and occupational therapy we hope all of our patients could get,” said Dr. S. Andrew Josephson, professor and chair of the Department of Neurology at the University of California San Francisco. “It’s a long process to get the brain to recover and rewire, but we have more and more science that tells us that these types of aggressive rehabilitation approaches end up helping people have better outcomes.”

One thing Shortz wishes he’d done differently is to work his left arm as early and as much as he worked on everything else. Initially, he said, he treated it as you would an injury that needs rest to heal on its own.

“I didn’t use it very much,” he recalled. “But when you’ve had a stroke, what you want is for your brain to reconnect or make new connection with your neurons, your nervous system. So I should have been using my arm as much as possible from the start.”

By April, Shortz was facing an important event, one he hadn’t missed since he founded it in 1978: the annual American Crossword Puzzle Tournament. He left the subacute rehabilitation facility, went home and went to the tournament in a wheelchair.

“I’m so glad I did,” Shortz said. “When I was wheeled into the ballroom with almost 1,000 people, there was a standing ovation, which was very rewarding.”

The myth of the ‘golden window’

Since then, Shortz said, he’s continued therapy seven days a week. He does outpatient physical and occupational therapy at a nearby hospital twice a week, working with a therapist at home and going to a local place called Rehabologym that has an approach he particularly enjoys: “You play games and do exercises,” Shortz said. He’s also continued table tennis.

Varying exercises in that way is an important part of strengthening the brain, Gupta said.

“The best way to exercise the brain is to work different parts of it – so adding in movement, like Will, and doing new activities is what helps keep the brain growing and working at its optimal level,” he said.

Shortz said he can now walk with a cane and is starting to get some use of his left hand back, and he feels that he’s still improving.

“I’ve heard and read that all the progress you can make in recovery from a stroke is going to happen within three to six months,” he said. “A lot of stroke victims have written me since then that that is not true, that you continue to make improvement, really for the rest of your life.”

It’s true that recovery can continue beyond what was previously thought of as the “golden window” of the first six months, Lin said. “I do not think that there’s a timestamp to recovery, because our brain is really quite plastic,” she said.

Josephson agreed. “We know that the brain continues to heal for many years to come,” he added.

Overcoming plateaus

Shortz said the hardest times in his recovery have been when he’s hit plateaus and started to wonder, “Is this how I’m going to have to be for the rest of my life?”

In those times, he said, “it’s like any time you’re faced with a problem that seems insurmountable or seems very complex: The thing to do is just pick some one small element of it and work at that.”

“I have always kept working at this, and then I have a new breakthrough,” Shortz said.

If that sounds a lot like how one might try to tackle a crossword puzzle, that’s no coincidence.

“Like solving a crossword puzzle,” Shortz said, “even if you don’t know certain things that are in the puzzle, tackle what you do know. Get those under your belt. And each thing that you do will lead on to something else you can do. And afterward, when you finish the puzzle, you think, ‘Wow, I didn’t realize I could do that.’”

Disruptions from Hurricane Helene exacerbated shortages of critical intravenous fluids in the United States, and now the Biden administration has invoked the wartime powers of the Defense Production Act in the latest move to help speed recovery efforts.

As the storm swept through western North Carolina last month, it severely affected operations at Baxter International’s North Cove production site, the largest manufacturer of IV fluids and dialysis solutions in the country. After a pause, Baxter resumed distribution of supplies – but with significant restrictions on the amount that could be ordered. Since last week, Baxter has expanded order capacity to up to 60% of typical volume for some of the most in-demand IV fluids.

But the strain persists. The US Food and Drug Administration has declared multiple shortages as a result, and hospitals have been rationing supplies – and postponing surgeries, in some cases – as the national supply chain continues to reel from the blow.

On Saturday, the US Centers for Disease Control and Prevention issued a health advisory about the shortages, warning health care providers that “the supply disruption may impact patient care and require adjustments to the clinical management of patients.”

Last week, the FDA announced that it is allowing the importation of products from five facilities outside the US to help alleviate the shortfall. And other US manufacturers, B Braun Medical and ICU Medical, are ramping up production to help fill the gaps.

But Baxter’s North Cove facility is a critical part of the supply chain; it typically produces about 60% of the IV fluids for hospitals across the country.

The US Department of Health and Human Services has now invoked the Defense Production Act to help Baxter obtain materials to clean and rebuild. Under the authorities of the law, Baxter will have priority access to a particular material needed to continue the remediation process and prepare for the restart of production. HHS’s Administration for Strategic Preparedness and Response is working with Baxter to identify other challenges and will pursue other opportunities to make use of the Defense Production Act, an agency spokesperson said.

“Ensuring people have medical supplies they need is a top priority of the Administration. It’s exactly why we are working closely with Baxter to support cleanup and restoration of the facility, including invoking the Defense Production Act to help production resume as quickly as possible,” an HHS official said in a statement Tuesday.

The Defense Production Act was passed in 1950 in response to the Korean War. The law gives the government – particularly the president – more authority to direct resources for industrial production during emergencies.

It was used during the Covid-19 pandemic by the Biden and Trump administrations to bolster production of supplies used in response efforts, including vaccines and ventilators. It was part of recovery efforts after Hurricane Maria hit Puerto Rico in 2017, which also affected Baxter facilities and led to shortages of IV bags used to administer and dilute medications that lasted months.

In an update Monday, Baxter said there is “good progress on site cleanup and remediation” at the North Carolina location. A temporary rock bridge replaced one that was damaged by the storm, and a second bridge is being built to allow more product and equipment to come and go from the facility.

“Current priorities are completing deep cleaning of the facility, including floors and equipment, as well as assessing the status of all equipment and production lines,” the company said. It aims to restart production at the affected site by the end of the year, but it will happen in phases, and there is no definitive timeline on when production levels will be fully restored.

Allocations for IV solutions and nutrition products for children’s hospitals have been restored to full capacity, and some other IV solution products could return to full allocation by the end of the year, the company said.

The major disruptions to the IV fluid supply after Hurricane Helene are the latest in a string of challenges that have exposed vulnerabilities to the broader US supply chain.

There were a record number of drugs in active shortage in the US in the first three months of 2024, according to data from the American Society of Health-System Pharmacists and the University of Utah Drug Information Service. The situation has improved somewhat in recent months, but there have been at least 300 active shortages for the past year and a half.

Adding a six-week course of chemotherapy to the standard course of treatment for locally advanced cervical cancer resulted in a significant increase in survival rates, a new study shows.

The study, published Monday in the journal The Lancet, involved 500 patients from 32 medical centers in Brazil, India, Italy, Mexico and the UK who were randomly assigned into two groups between 2012 and 2022. All had locally advanced cervical cancer, although none had tumors that had spread to other organs.

The control group received only chemoradiotherapy, a standard process that included treatment with radiation and the drug cisplatin. The experimental group received six weeks of treatment with carboplatin and paclitaxel chemotherapy before beginning chemoradiotherapy.

The researchers found that 80% of those who got a short course of chemotherapy first lived at least five more years, and 72% did not have any cancer return or spread. In the control group, 72% survived at least five years, and 64% had no cancer return or spread.

Most patients had some kind of adverse event during treatment, including fatigue or weakness, gastrointestinal problems, infections or low white blood cell counts. Severe or life-threatening events happened in 59% of the group that got initial chemotherapy, compared with 48% of those who got chemoradiotherapy alone.

The researchers say theirs is the first randomized phase three study to show a “significant survival advantage” using chemotherapy before chemoradiotherapy, representing a “clinically meaningful improvement” at a “relatively low cost.” The drugs are cheap and widely available, they say.

“This is the biggest improvement in outcome in this disease in over 20 years,” Dr. Mary McCormack of University College Hospital, lead author of the study, said in an interview with Cancer Research UK. “I’m incredibly proud of all the patients who participated in the trial; their contribution has allowed us to gather the evidence needed to improve treatment of cervical cancer patients everywhere.”

Cisplatin-based chemotherapy is one of the most commonly used methods of treating cervical cancer, improving survival rates by 30% to 50%. While tumor removal surgery is an option, some experts tend to prefer chemotherapy.

“We know that surgery is going to leave some of the cancer behind,” said Dr. Otis Brawley, a professor of oncology at Johns Hopkins University and former chief medical officer of the American Cancer Society, who was not involved with the new research. “If you can treat with radiation and chemotherapy, you have a chance that you’re going to sterilize the pelvis of all of the cancer. … We have the chances that we’re going to put women into a prolonged, complete remission.”

Cervical cancer was once the leading cause of cancer death for women in the United States, he noted. In 2008, Harald zur Hausen, a German virologist, won the Nobel Prize for his research demonstrating that cervical cancer in humans is caused by certain types of human papillomavirus, or HPV. This discovery led to the development of an HPV vaccine that can help prevent cervical cancer in women.

However, cervical cancer still kills about 4,000 women in the US each year. Warning signs include abnormal bleeding or discharge.

Brawley stressed the importance of routine cervical screening as advanced-stage cervical cancer rises among White and Black women in the US.

According to the US Centers for Disease Control and Prevention, cervical cancer screenings typically test for signs of HPV that can cause cell changes on the cervix. The screenings also include a Pap test to look for precancer cell changes.

The US Food and Drug Administration greenlit a new option this year for patients to collect their own vaginal samples to test for HPV, streamlining the screening process.

“It’s almost totally preventable with either the HPV vaccine or screening,” Brawley said. “Of the 4,400 deaths from cervical cancer, none of them get screened every year.”

Chemotherapy to treat cervical cancer can come with unpleasant side effects like nausea, vomiting and hair loss, Brawley noted. He hopes the future of treatment will involve more personalized options like immunotherapy, which uses a person’s own immune system to fight cancer.

“The greatest hope is immunotherapy,” he said. “We’re hoping we can actually help even more women with less side effects.” 

Coca-Cola has recalled more than 13,000 cases of Minute Maid Zero Sugar Lemonade because the mislabeled cartons actually contained the full-sugar version of the drink, according to a report from the US Food and Drug Administration.

The FDA considers this a class II recall, involving a “health hazard situation where there is a remote probability of adverse health.”

One can of Minute Maid Lemonade has 40 grams of sugar, according to product information on Amazon.

The 12-pack cartons of the canned drink were shipped to retailers in Indiana, Kentucky and Ohio. Consumers can identify the recalled products by looking for codes FEB1725CNA or FEB1725CNB printed on the packaging.

The recall started in early September, but a news release was not issued at the time.

According to the FDA, the event is considered ongoing.

After years of continuously rising opioid overdoses, the US Centers for Disease Control and Prevention reported that overdose deaths decreased 3% in 2023, the first annual decrease since 2018. A new study shows how the increased administration of naloxone by non-medical laypersons – or bystanders with little to no medical training – could be one factor contributing to this decline.

Making naloxone, a drug used to reverse opioid overdose that’s commonly known as Narcan, more widely available has been part of concentrated efforts to increase layperson intervention.

The new study, published Monday in the journal JAMA Network Open, says that from June 2020 to June 2022, emergency medical services reported 744,078 patients receiving naloxone across the US. The researchers found that EMS-documented naloxone administration rates fell 6.1% in this period, but the percentage of people who got naloxone from a layperson before EMS arrival increased 43.5%.

“The fact that we saw an increase of 43.5%, we can tell that public health efforts are working,” said Chris Gage, lead author of the study and EMS Research Fellow with the National Registry of Emergency Medical Technicians.

Naloxone, which is commonly used as a nasal spray, reverses an overdose by blocking the effects of opioids. The medication restores breathing within two to three minutes in people whose breath has slowed or stopped due to overdose, often with just one dose. However, experts recommend calling 911 any time someone is overdosing, since they may need medical attention even after getting naloxone.

“There’s no real medical training required,” Gage said. “It’s pretty much as easy as spraying Afrin up someone’s nose. Just showing people that they could do something to potentially save someone’s life is the ultimate goal.”

The latest CDC data continues a recent downward trend in fatal overdoses in the US, which have fallen as much as 10% over the past year. The new research’s “significant increase” in layperson naloxone usage underscores the drug’s evolving role in public health strategies to address the opioid crisis, putting the medication in the hands of bystanders who can help save lives before emergency workers arrive.

“People who reverse overdoses are very likely to reverse more than one overdose,” said Dr. Nabarun Dasgupta, a senior scientist at the University of North Carolina at Chapel Hill who was not involved with the new research. “The evidence base for the effectiveness of naloxone is really focused on getting naloxone into the people who use drugs and the people who are around them.”

Only 3.4% of the 744,078 naloxone recipients in the study got the drug from a layperson, and Gage hopes that the number will continue to increase. Naloxone became available over the counter in September 2023 with a suggested retail price of about $45 per two-dose carton.

“Naloxone is a life-saving medication,” Gage said. “We’re in the middle of an opioid epidemic. Now that it’s over-the-counter, there should be even more access for people to be able to get this. If someone knows someone that has opioid addiction, they could potentially give a life-saving medication.”

Despite its increased availability, barriers still keep some opioid users from accessing naloxone.

“Narcan nasal spray has been a multibillion-dollar monopoly for the better part of a decade,” Dasgupta said. “That’s changed over the last year and a half, but … states are paying more for naloxone than they should.”

He added that more education should be offered on what may be in the drugs that opioid users consume.

“There is a rapidly growing paradigm of drug-checking where we are able to analyze on the spot what is in an actual drug sample,” Dasgupta said. “What we find is, most drug supply is highly contaminated. We often see people throw away their drugs or make a decision whether to take that or not.”

Gage said the new findings can help inform policies and practices aimed at reducing the effects of the opioid epidemic.

“If more laypeople are giving the administration of naloxone, then hopefully that means that these people aren’t dying,” he said.

Your nose may be more powerful than you think.

In a single sniff, the human sense of smell can distinguish odors within a fraction of a second, working at a level of sensitivity that is “on par” with how our brains perceive color, “refuting the widely held belief that olfaction is our slow sense,” a new study finds.

Humans also can discern between various sequences of odors – distinguishing a sequence of “A” before “B” from sequence “B” before “A” – when the interval between odorant A and odorant B is merely 60 milliseconds, according to the study, published Monday in the journal Nature Human Behaviour.

“We were astonished to observe that participants could distinguish between two odorants presented in one order and the reverse when the latency between the odorants was as short as 60 milliseconds,” Dr. Wen Zhou, lead author of the study and a principal investigator at the Chinese Academy of Sciences in Beijing, said in an email. Latency refers to the time between when each scent is delivered.

“For comparison, the duration of an eye blink is about 180 milliseconds,” Zhou added.

“Our apparatus could be used for therapeutic purposes, such as olfactory training for patients with olfactory loss,” Zhou said. “More broadly, our findings could guide the design and development of electronic noses and olfactory virtual reality systems, which could have significant clinical benefits.”

The researchers, from the University of Chinese Academy of Sciences and the Ohio State University, developed a sniff-triggered apparatus that included check valves – devices that allow odor to flow in one direction – and Teflon tubes, capable of delivering odors to the human nose with a precision of 18 milliseconds. The researchers asked 229 adults in China to wear this device and smell different odor mixtures: two odors presented in quick succession within a single sniff.

The odors included apple-like scents, sweet floral scents, lemon-like scents and onion-like scents. The latency between the two odors was carefully manipulated.

The researchers analyzed whether participants could distinguish between two odors presented in one order and the reverse at different latencies.

They found that, overall, two odors presented in one order and the reverse became “perceptually discriminable” when the two odors were only 60 milliseconds apart within a single sniff, Zhou said.

The researchers noted that they used only four odorants and that it would be beneficial to test a wider variety to determine whether the human sense of smell is more sensitive to certain odor dynamics or compounds.

“This could provide a deeper understanding of the computational principles underlying our olfactory experience,” Zhou said.

The new findings challenge previous research in which the timing it took to discriminate between odor sequences was around 1,200 milliseconds, Dr. Dmitry Rinberg, a professor in the Department of Neuroscience and Physiology at NYU Langone Health in New York, wrote in an editorial accompanying the study in Nature Human Behaviour.

“The timing of individual notes in music is essential for conveying meaning and beauty in a melody, and the human ear is very sensitive to this. However, temporal sensitivity is not limited to hearing: our sense of smell can also perceive small temporal changes in odour presentations,” he wrote. “Similar to how timing affects the perception of notes in a melody, the timing of individual components in a complex odour mixture that reaches the nose may be crucial for our perception of the olfactory world.”

The ability to tell apart odors within a single sniff might be an important way in which animals detect both what a smell is and where it might be in space, said Dr. Sandeep Robert Datta, a professor in the Department of Neurobiology at Harvard Medical School, who was not involved in the new study.

“The demonstration that humans can tell apart smells as they change within a sniff is a powerful demonstration that timing is important for smell across species, and therefore is a general principle underlying olfactory function. In addition, this study sheds important light on the mysterious mechanisms that support human odor perception,” Datta wrote in an email.

“The study of human olfaction has historically lagged that of vision and hearing, because as humans we think of ourselves as visual creatures that largely use speech to communicate,” he said, adding that the new study helps “fill a critical gap in our understanding of how we as humans smell.”