It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, February 09, 2023
Whiskers help nectar-eating “acro bats” hover like hummingbirds
Extra-long hairs provide enhanced spatial information for orientation and feeding
VIDEO: NECTAR-EATING BATS EVOLVED EXTRA-LONG WHISKERS THAT PROVIDE ENHANCED SPATIAL INFORMATION AS THE ANIMALS DART FROM FLOWER TO FLOWER TO FEED WITHOUT LANDING.view more
CREDIT: ERAN AMICHAI
From dragonflies to hummingbirds, hovering flight is among the most complex and captivating forms of animal movement—a physiological feat of size, musculature and wing development.
For nectar-feeding bats that hover as they feed from flowers, this aerial maneuver also depends on extra-long whiskers unlike those of most other bat species, according to a Dartmouth College-led study in the journal Proceedings of the Royal Society B. The researchers used high-speed cameras to capture how the stiff hairs jutting forward from the face of nectar-eating bats provide enhanced spatial information that guides the animals as they swoop in to quickly feed—within a second or less—on succulent flowers without landing.
“The whiskers of nectar-feeding bats are critical sensory organs that provide high-quality input the brain works with to optimize hovering. It’s a cool junction between sensory biology and bio-kinematics, between form and function,” said lead author Eran Amichai, a postdoctoral researcher in biological sciences at Dartmouth who studies echolocation in bats. Co-authors are postdoctoral fellow David Boerma from the American Museum of Natural history, animal behavioralist Rachel Page at the Smithsonian Tropical Research Institute in Panama, Sharon Swartz, a professor of biology and engineering at Brown University, and Hannah ter Hofstede, a past assistant professor of biological sciences at Dartmouth now at the University of Windsor in Canada.
The researchers worked at the Smithsonian Tropical Research Institute recording Pallas’s long-tongued bats—a South and Central American bat that has the fastest metabolism of any mammal—as they drank from hand-blown glass flowers designed for the study to replicate the plants the animals feed from. High-speed infrared cameras captured photos and video of the bats as they descended upon the glass flowers and navigated their muzzles and tongues into the “bloom” to eat the nectar. Feedings typically lasted between a half- to one second.
The researchers found that bats with clipped whiskers were less agile and accurate during feeding and flight than animals with untouched whiskers. The animals with clipped whiskers were held for a few days until the hairs regrew, then released back into the jungle. “Clipping the whiskers doesn’t reduce the bats’ ability to feed, they just do it a little less gracefully,” Amichai said. “If it were gymnastics, they’d get an 8.5 instead of a 9.8.”
The role of long whiskers in nectar-feeding bats’ flight control provides new insight into the coevolution of the bats with the flowers they feed on, Amichai said. The majority of bats possess short whiskers not arranged in any particular pattern or direction. But the researchers found that whisker length in nectar-eating bats evolved at least twice to—along with long tongues and faces—potentially help them better navigate the deep chambers of the flowers they prefer. In turn, the long reach these flowers require results in more pollen sticking to their pollinators and thus the broader proliferation of their kind.
The researchers plan to continue their work using higher-resolution images, flowers that move, interactions with predators and other expansions on the experimental model, Amichai said.
In the meantime, the latest study offers a fascinating glimpse into how nectar-feeding bats combine various forms of sensory information to navigate the world around them, Amichai said. Their world is a combination of scent, echolocation, spatial memory, knowledge of the seasons and the physical sensation and equilibrium provided by their whiskers.
“I find thinking in these terms of switching back and forth between completely different ways to perceive the world—and seamlessly integrating their input—to be a mind-blowing concept,” Amichai said. Understanding how animals perceive and interact with their surroundings helps scientists develop better conservation strategies, he said.
“We are strange animals—we rely almost solely on vision and, to a lesser extent, hearing to perceive the world. As a result, we interpret other animals' behavior in similar terms and that often leads us to completely misinterpret what they're doing and why,” Amichai said. “Understanding the sensory world of other animals helps us ‘see the world through their eyes’ and understand their behavior, needs and challenges better.”
The paper, “By a Whisker: The Sensory Role of Vibrissae in Hovering Flight in Nectarivorous Bats,” was published Feb. 1 by the Proceedings of the Royal Society B. The work was supported by a Journal of Experimental Biology Travelling Fellowship (JEBTF1911291) from The Company of Biologists.
High-speed cameras captured nectar-eating Pallas’s long-tongued bats as they fed from glass tubes designed for the study to replicate the animals' preferred flowers.
CREDIT
Eran Amichai
JOURNAL
Proceedings of the Royal Society B Biological Sciences
IMAGE: RESEARCHERS NÉHÉMIE GUILLOMAITRE AND XIAOHUI XU HOLD A SAMPLE OF THE SOLAR ABSORBER GEL, WHICH ACTS LIKE A SPONGE TO SOAK UP CLEAN WATER AND FILTER OUT CONTAMINANTS.view more
CREDIT: BUMPER DEJESUS/PRINCETON UNIVERSITY
Worldwide, over two billion people lack reliable access to clean water. And one potential solution for meeting that need works a lot like a sponge, soaking up clean water while leaving contaminants behind.
Researchers at Princeton University have developed the next generation of their solar absorber gel technology, a device that could be key to unlocking clean water access for people across the globe. The sponge-like gel is low-cost, easy-to-use, and requires only sunlight to filter pollutants such as heavy metals, oils, microplastics, and some bacteria from water, making it an alternative for off-grid water purification.
The device demonstrates an almost fourfold increase in filtration rate over the first-generation technology, which was developed in 2021. A square meter of the one-centimeter-thick material can produce over a gallon of water in as little as 10 minutes and could provide enough clean water to meet daily demand in many parts of the world. The details of the new solar absorber gel were published on Feb. 8 in ACS Central Science.
“There have been many efforts to develop a technology that uses solar energy to create clean, potable drinking water, but they often fail to produce enough water to meet daily need,” said Rodney Priestley, Dean of the Graduate School, Pomeroy and Betty Perry Smith Professor of Chemical and Biological Engineering, and associated faculty at the Andlinger Center for Energy and the Environment. “This latest iteration of our technology gets us another step closer towards the goal of having a technology driven by solar energy that can actually produce enough clean water to meet daily demand.”
At the core of the device’s sponge-like appearance is a gel formed from a polymer known as poly(N-isopropylacrylamide) or PNIPAm, which can either absorb or release water, depending on the temperature.
Below 33 degrees Celsius (91 degrees Fahrenheit), this hydrogel acts like a sponge to absorb water from a source such as a lake. But when the hydrogel is removed from the water and heated by sunlight to a temperature above 33 degrees, it begins to release the water. With the addition of polymers such as polydopamine (PDA) to the gel’s surface, the device can filter contaminants like oils, heavy metals, microplastics, and some types of bacteria from the water.
The researchers said the gel is less expensive and simpler to use than existing systems that rely on evaporation. Users simply toss the sponge-like device in a water source until it becomes saturated. Then they remove it from the water, place it in sunlight, and wait for it to release filtered water. Under the midday sun, the gel can release around 70% of the water it absorbs in as little as ten minutes.
“Our first solar absorber gel already had strong performance,” said Xiaohui Xu, a presidential postdoctoral fellow at Princeton University and the study’s first author. “But we wanted to continue making the device even more efficient at filtering water.”
According to Xu, the dramatic increase in filtration speed stems from changes the researchers made to the hydrogel’s structure between the first and second generations that enhanced its ability to transport water. While both the first and second generations utilize the same PNIPAm hydrogel, the researchers found they could change the gel to have a more interconnected, fibrous structure by synthesizing the polymer in a mixture of water and ethylene glycol.
Xu said the unconventional approach led to a key improvement over most existing hydrogels, which tend to have a honeycomb-like structure with walls that impede water transport. She compared the interconnected, fibrous structure of the new hydrogel to that of a mature loofah-fruit, which is commonly used as a scrubbing sponge in bathrooms and kitchens.
In addition to its enhanced filtration speed, Néhémie Guillomaitre, study co-author and a graduate student in chemical and biological engineering, added that the second-generation solar absorber gel sports other improvements over its predecessor.
For example, the researchers gave the solar absorber gel anti-fouling properties by adding another polymer, poly(sulfobetaine methacrylate) (PSBMA), to the surface of the gel. Not only does PSBMA help the device filter contaminants from water even more efficiently, but it also binds tightly with water molecules at the gel’s surface to form a hydration layer that repels oil and bacteria, which allows the device to be self-cleaning.
“Having anti-fouling properties helps the gel last longer,” Guillomaitre said. “There is less of a need to worry about oils and bacterial films accumulating on the gel’s surface over time and lowering its efficiency.”
The researchers ultimately believe the solar absorber gel could scale to become an attractive option for water purification at the household level and could provide access to clean water without needing to rely on energy from the grid.
“Ideally, this technology could one day be used by anyone concerned about their water quality, regardless of where they live,” Guillomaitre said.
While the researchers noted that they are still working to create prototypes to demonstrate their device can be scaled to household use, Priestley said in the near term, he believes the solar absorber gel could be used in emergency situations to provide on-demand access to clean water.
With support from the National Science Foundation, the research has led to the launch of a startup, AquaPao, co-founded by Priestley, which will continue to iterate and improve the design of the solar absorber gel, test its long-term durability, and identify opportunities to scale up the technology.
“This work is a wonderful example of how academic research can be translated into the startup world,” said Priestley. “Through our work, we have been able to show that fundamental research may have significant impact on society.”
The article, “Quick Release Anti-Fouling Hydrogels for Solar-Driven Water Purification,” was published in ACS Central Science on Feb. 8. In addition to Xu, Guillomaitre, and Priestley, authors include Kofi Christie, R. Kōnane Bay, Navid Bizmark, Sujit Datta, and Z. Jason Ren, of Princeton University.
The work was supported by the National Science Foundation Materials Research Science and Engineering Centers, the Eric and Wendy Schmidt Transformative Technology Fund at Princeton University, the Project X fund, and the Princeton Catalysis Initiative.
IMAGE: A POROUS HYDROGEL INSPIRED BY LOOFAH SPONGES ABSORBS POLLUTED WATER AT ROOM TEMPERATURE AND THEN RAPIDLY RELEASES PURIFIED WATER WHEN HEATED.view more
CREDIT: ADAPTED FROM ACS CENTRAL SCIENCE 2023, DOI: 10.1021/ACSCENTSCI.2C01245
Access to clean water is being strained as the human population increases and contamination impacts freshwater sources. Devices currently in development that clean up dirty water using sunlight can only produce up to a few gallons of water each day. But now, researchers in ACS Central Science report how loofah sponges inspired a sunlight-powered porous hydrogel that could potentially purify enough water to satisfy someone’s daily needs — even when it’s cloudy.
Previously, researchers have suggested that sunlight-driven evaporation could be a low-energy way to purify water, but this approach doesn’t work well when it’s cloudy. One solution could be temperature-responsive hydrogels, specifically poly(N-isopropyl acrylamide) (PNIPAm), that switch from absorbing water at cooler temperatures to repelling it when heated. However, conventional PNIPAm gels can’t generate clean water fast enough to meet people’s daily needs because of their closed-off pores. Conversely, natural loofahs, which many people use to exfoliate in the shower, have large, open and interconnected pores. So, Rodney Priestley, Xiaohui Xu, and colleagues wanted to replicate the loofah’s structure in a PNIPAm-based hydrogel, yielding a material that could rapidly absorb water at room temperature, and rapidly release purified water when heated by the sun’s rays under bright or cloudy conditions.
The researchers used a water and ethylene glycol mixture as a uniquely different polymerization medium to make a PNIPAm hydrogel with an open pore structure, similar to a natural loofah. Then they coated the opaque hydrogel’s inner pores with polydopamine (PDA) and poly(sulfobetaine methacrylate) (PSMBA), and tested this material using an artificial light equivalent to the power of the sun. It absorbed water at room temperature and, when heated by the artificial light, released 70% of its stored water in 10 minutes — a rate four times greater than the one for a previously reported absorber gel. The researchers say that, at this rate, the material has the potential to meet a person’s daily demand. And under lower light conditions, replicating partly cloudy skies, it took 15 to 20 minutes for the material to release a similar amount of stored water.
Finally, the new loofah-like material was tested on samples polluted with organic dyes, heavy metals, oil and microplastics. In all of the tests, the gel made the water substantially cleaner. For example, in two cycles of treatment, water samples with around 40 parts per million (ppm) chromium were absorbed, then released with less than 0.07 ppm chromium — the allowable limit for drinking water. The researchers say the unique hydrogel structure that they created could be useful in additional applications, such as drug delivery, smart sensors and chemical separations.
The authors acknowledge funding from a Princeton University Presidential Postdoctoral Fellowship, a National GEM Consortium Fellowship, the U.S. National Science Foundation, the Eric and Wendy Schmidt Transformative Technology Fund at Princeton University, the Project X Fund at Princeton University and the Princeton Catalysis Initiative.
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CREDIT: CENTER FOR WHALE RESEARCH (PHOTO TAKEN BY KENNETH BALCOMB) ANY USE OF THIS PHOTO MUST BE ACCOMPANIED BY THE RESEARCH PERMIT NUMBER, NMFS 21238, EITHER WATERMARKED ON THE MEDIA ITSELF, IN THE CAPTION, OR ELSEWHERE IN THE PIECE.
It’s not unusual for parents and especially mothers to sacrifice their own future success for the sake of their offspring. Now a new study in Current Biology on February 8 shows that killer whale mothers take this to a surprising extreme. They sacrifice their own reproductive success to care for their sons, even after those sons are full-fledged adults.
“We’ve known for over a decade that adult male killer whales relied on their mothers to keep them alive, but it had never been clear whether mothers pay a cost to do so,” said Michael N. Weiss (@CetaceanMike) of the University of Exeter, UK, and the Center for Whale Research in the US.
Now it is. Weiss and his colleagues studied a group of killer whales known as the “southern resident” population in the coastal waters of Washington state and British Columbia, which has been monitored since 1976 by the Center for Whale Research. They wanted to learn whether the care adult whales, and especially males, receive from their mothers came at a measurable cost. The availability of detailed demographic data allowed them to look directly at how caring for sons and daughters impacted females’ chances of further reproduction.
“The southern resident killer whale community presents an incredible opportunity to investigate these kinds of questions,” Weiss said. “Along with their bizarre social system, where both males and females stay with their mom for life, they are also one of the best studied wild populations of mammal anywhere in the world.”
Their analysis of the existing data found a strong negative correlation between females’ number of surviving weaned sons and their annual probability of producing a viable calf. Those costs didn’t get any smaller as their sons grew older, either.
The costs couldn’t be explained by lactation or group composition effects, which they say supports the hypothesis that caring for sons into adulthood is reproductively costly. They say that the findings offer the first direct evidence for lifetime maternal investment in any animal, revealing a previously unrecognized life history strategy.
“The magnitude of the cost that females take on to care for their weaned sons was really surprising,” Weiss said. “While there’s some uncertainty, our best estimate is that each additional surviving son cuts a female’s chances of having a new calf in a given year by more than 50 percent. This is a huge cost to taking care of [adult] sons!”
The findings suggest that there are significant benefits to keeping adult sons alive and well, he added.
“Females gain evolutionary benefits when their sons are able to successfully reproduce, and our results indicate that these benefits are enough to outweigh a large direct cost,” Weiss explained.
The findings also may have important conservation implications, the researchers say. The southern residents are critically endangered, with one major concern being their low reproductive rates. The new findings reveal a major and previously unrecognized determining factor in a female’s reproductive success, which may help to inform future population viability analyses.
“One big take-away is further evidence for how special (and maybe unique) the mother-son bond in killer whales is,” Weiss said. “Maybe more importantly, our study adds to the growing body of work showing the importance of animals’ social systems in determining demographic patterns. This is of central importance both for an understanding of our world, and to effectively conserve endangered species.”
In future work, they hope to learn more about the nature of the costs to mother whales. They suspect mothers may not eat enough themselves as they continue sharing food with their full-grown sons. He noted that the southern resident killer whales are “very food-stressed.” As such, a primary conservation goal for the whales is to recover the population of Chinook salmon they rely on.
Killer Whales
CREDIT
Center for Whale Research (Photo taken by David K. Ellifrit) Any use of this photo must be accompanied by the research permit number, NMFS 21238, either watermarked on the media itself, in the caption, or elsewhere in the piece.
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
Costly lifetime maternal investment in killer whales
ARTICLE PUBLICATION DATE
8-Feb-2023
An evaluation of the "Aunt Jemima" product rebrand suggests that consumers may be less likely to like, trust and buy a product after such a change - even when informed of the intention to address racism
An evaluation of the "Aunt Jemima" product rebrand suggests that consumers may be less likely to like, trust and buy a product after such a change - even when informed of the intention to address racism
UNIVERSITY OF CALIFORNIA - BERKELEY HAAS SCHOOL OF BUSINESS
Imagine you’re browsing the toothpaste aisle and see next to Colgate a new brand called Colddate, packaged in a box with similar colors and designs. “You might think this is clearly a copycat brand,” said Ming Hsu, William Halford Jr. Family Chair in Marketing at the Haas School of Business, UC Berkeley.
Yet in a real-life trademark infringement case involving these two brands, Colgate-Palmolive lost the suit, with the judge saying they were “similar” but not “substantially indistinguishable.”
There are often different opinions between judges and juries in trademark cases about how similar the brands in question actually are, leading to large inconsistencies in the application of the law. In a paper published February 8 in the journal Science Advances, Hsu and colleagues propose a more scientific measure through the use of brain scans—employing functional magnetic resonance imaging (fMRI) along with a specialized technique called repetition suppression (RS).
“Asking the brain, not a person, could reduce—if not eliminate—these inconsistencies,” said lead author Zhihao Zhang, a former Berkeley Haas postdoctoral researcher now on the faculty of the Darden School of Business, University of Virginia. The study’s other authors include Dr. Andrew Kayser of UC San Francisco, Femke van Horen of Vrije University Amsterdam, and Mark Bartholomew of University at Buffalo Law School.
What is “similarity”?
The standard according to the law is whether a “reasonable person” would find two trademarks similar, but it doesn’t define what similar means.
“Similarity is an incredibly hard thing to measure in an objective way,” said Zhang. “Making things worse, in the adversarial legal system, two opposing parties each hire their own attorneys and expert witnesses who present their own evidence.”
Often that evidence takes the form of consumer surveys, which have been shown to be susceptible to manipulation—for example, through the use of leading questions. Not surprisingly, plaintiffs are known to present surveys finding that the two trademarks are similar, while defendants present competing surveys showing they are different.
“There is no gold standard in the law about what background information survey respondents receive, how the questions are phrased, and what criteria of ‘similarity’ should be followed— all factors that can change the results substantially,” Zhang said. “Judges have a lot of experience with these situations, and have developed some degree of cynicism.”
Oftentimes, Hsu added, judges just say, ‘I don’t believe any of you, I’m going to go with my own gut.’ It’s easy to sympathize with these judges, who just throw up their hands.”
Putting brains on the witness stand
In their paper, the researchers demonstrated how looking directly into the brain may help solve this conundrum. They put participants in fMRI scanners, and rapidly showed them pairs of images consisting of the main brand and a supposed copycat. Previous research has consistently shown that when presented with two similar images, the brain suppresses activity for the second image, perhaps out of efficiency, thinking it’s already seen the image. By measuring the amount of repetition suppression (RS) in brain activity for the second image, the researchers determined how similar a person found the two images.
The resulting approach provides an important benefit: Participants are blind to the goal of the study, which further reduces bias. “This is because we don’t have to ask them any questions at all or tell them what it means to be similar or not,” said Hsu.
“In fact, even the experimenter administering the study doesn’t need to know its purpose, which makes it a ‘double-blind’ study like the rigorous clinical studies in drug development,” added Kayser.
Indeed, when the research team checked the results of the neuroimaging against survey results that are intended to be pro-plaintiff, pro-defendant, or neutral, they found the brain-based measure can reliably pick out the more neutral survey results, supporting the idea that the brain scans can improve the quality of legal evidence in these cases.
This kind of evidence could be provided as a supplemental “spot check” to survey evidence, giving a judge or jury confidence the surveys are accurate, Hsu said. The cost of using neuroimaging is comparable to presenting survey data, the researchers said.
Scientists provide the ruler, courts draw the line
Importantly, the brain-based measures don’t take away the need for judgment by the court. “Our method still doesn’t say how similar is too similar,” said Kayser. “Our job as scientists is to provide a better ruler. It’s still up to the judge to decide where to draw the line.”
More broadly, introducing new techniques like this will require more discussion between disciplines and a better understanding by legal practitioners of what value these techniques deliver, said Bartholomew, who served as the legal expert on the research team. “Courts have an important role in deciding when new kinds of scientific insights should be allowed in to potentially influence the outcome of a case,” he said. “This gatekeeping role means that both judges and the lawyers appearing before them increasingly need to have a working knowledge of neuroscientific techniques.”
While this study only looked at visual trademark cases, the researchers say this kind of neural measure holds promise for a wide range of legal applications revolving around people’s mental reactions—for example, determining copyright infringement in music cases, or determining how a “reasonable person” would judge obscenity, negligence, or other legal issues.
“It’s striking how often people’s opinions matter in the courts, and how often this standard of a ‘reasonable person’ is applied in the law,” Hsu said. “While we are not there yet, one can imagine a future where we ask the brain to help us answer these difficult questions.”
JOURNAL
Science Advances
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
People
ARTICLE TITLE
From Scanner to Court: A Neuroscientifically Informed “Reasonable Person” 5 Test of Trademark Infringement
ARTICLE PUBLICATION DATE
8-Feb-2023
National study of US hospitals finds low adherence to the federal price transparency mandate
In January 2021, the Centers for Medicare and Medicaid Services (CMS) passed a federal law that requires hospitals to make the costs of standard healthcare services transparent. Investigators at the Brigham systematically analyzed a nationally representative sample of all Medicare-registered acute-care hospitals across the U.S. for compliance with this law. Two independent reviewers evaluated whether each hospital adhered to the 21-point CMS hospital price transparency checklist and compared non-teaching vs teaching hospitals, non-profit vs for-profit hospitals, and hospitals in regions with different levels of regional market competition.
Researchers found that only 1 in 5, or 19 percent, of hospitals were fully adherent to the entire checklist. Teaching and non-profit hospitals were slightly more compliant than non-teaching or for-profit hospitals. Further, only 8 percent of hospitals in competitive markets, where patients may benefit the most from being able to compare prices, were compliant, compared to 33 percent in non-competitive markets. Findings suggest nationwide, patients are often unable to access information about hospital charges for basic services.
“The transparency mandate ensures patients can estimate how much their medical care might cost and shop around amongst competing hospitals to find the best price,” said senior author Haider J. Warraich, MD, of BWH’s Division of Cardiovascular Medicine. “However, our analysis found low compliance with the mandate. More efforts are needed to improve the state of healthcare financial toxicity in the country.”
Hospital Adherence to the Federal Price Transparency Mandate: Results from a Nationally Representative Sample
ARTICLE PUBLICATION DATE
17-Jan-2023
COI STATEMENT
Emefah Loccoh has no disclosures. Rohan Khera received support from the National Heart, Lung, and Blood Institute of the National Institutes of Health (under award K23HL153775) and the Doris Duke Charitable Foundation (under award, 2022060). He also receives research support, through Yale, from Bristol-Myers Squibb. He is a coinventor of U.S. Provisional Patent Applications 63/177,117 and 63/346,610, unrelated to current work. He is also a founder of Evidence2Health, a precision health platform to improve evidence-based cardiovascular care. Jeroen van Meijgaard and Tori Marsh are employees of GoodRx. Haider Warraich is a member of the GoodRx medical advisory board.
We still don’t know which factors most affect cognitive decline as we age
Study of 7,068 elderly Americans suggests more research is needed to inform healthy ageing strategies
IMAGE: THE AUTHORS ANALYZED DATA FROM 7,068 AMERICANS WHO WERE PART OF A LARGER STUDY THAT REGULARLY MEASURED THEIR COGNITIVE FUNCTION FROM 1996 TO 2016.view more
A new analysis explores relative statistical associations between various life factors and cognitive decline in elderly Americans, highlighting gaps in knowledge needed to reduce cognitive decline. Hui Zheng of the Ohio State University, U.S., and colleagues present these findings in the open-access journal PLOS ONE on February 8, 2023.
Millions of elderly Americans experience cognitive decline. However, only about 41 percent of this decline can be statistically accounted for by dementia—abnormal decline caused by such conditions as Alzheimer’s disease, cerebrovascular disease, and Lewy body disease. Prior research has identified many other factors that may also contribute to cognitive decline, from genetics to early life nutrition, but their relative impacts remain unclear.
To shed new light, Zheng and colleagues analyzed data from 7,068 American adults born between 1931 and 1941 who were part of a larger study—the Health and Retirement Study—that regularly measured their cognitive function from 1996 to 2016. The study also collected extensive information on personal factors that could contribute to cognitive decline, such as socioeconomic factors, physical health measures, and behaviors including exercise and smoking.
Together, the many factors considered in the study statistically accounted for 38 percent of the variation between participants in their level of cognitive function at age 54. Among those factors, personal education, race, household wealth and income, occupation, level of depression, and parental education were the biggest statistical contributors to that population-level variation, with early life conditions and adult behaviors and diseases contributing less.
However, all of the considered factors accounted for only 5.6 percent of the variation in how participants’ cognitive function changed with age.
Unlike many prior studies, this study also distinguished between age-related cognitive decline and cognitive decline that is unrelated to getting older. Age accounted for 23 percent of the variation in how cognitive function changed from age 54 to 85, but the remaining 77 percent could not be statistically accounted for by the many factors considered.
These findings suggest that more research is needed to identify the major factors contributing to rate of cognitive decline, which could help inform medical treatments, policies, and equity-based strategies to slow decline.
Hui Zheng adds: “Adulthood socioeconomic conditions have a predominant role in shaping the level of cognitive functioning. Future research is urgently needed to discover the main determinants of the slope of decline to slow down the progression of cognitive impairment and dementia.”
Kathleen Cagney adds: “Understanding cognitive health, and cognitive decline, is paramount. We must take the long view, with attention to the timing and nature of life experiences, if we are to gain fundamental insights that can inform care and treatment.”
Citation: Zheng H, Cagney K, Choi Y (2023) Predictors of cognitive functioning trajectories among older Americans: A new investigation covering 20 years of age- and non-age-related cognitive change. PLoS ONE 18(2): e0281139. https://doi.org/10.1371/journal.pone.0281139
Author Countries: USA
Funding: The authors received no specific funding for this work.
Predictors of cognitive functioning trajectories among older Americans: A new investigation covering 20 years of age- and non-age-related cognitive change
