In the Jan. 25, 2023 online edition of Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, the team reported that, among women aged 65 or older, each additional 31 minutes per day of moderate-to-vigorous physical activity was associated with a 21 percent lower risk of developing mild cognitive impairment or dementia. Risk was also 33 percent lower with each additional 1,865 daily steps.

“Given that the onset of dementia begins 20 years or more before symptoms show, the early intervention for delaying or preventing cognitive decline and dementia among older adults is essential,” said senior author Andrea LaCroix, Ph.D., M.P.H., Distinguished Professor at the Herbert Wertheim School of Public Health and Human Longevity Science at UC San Diego.

While there are several types, dementias are a debilitating neurological condition that can cause loss of memory, the ability to think, problem solve or reason. Mild cognitive impairment is an early stage of memory loss or thinking problems that is not as severe as dementias.

According to the United States Department of Health and Human Services, dementia affects more than 5 million people in this country. That number is expected to double by 2050.

More women live with and are at higher risk of developing dementia than men.

“Physical activity has been identified as one of the three most promising ways to reduce risk of dementia and Alzheimer’s disease. Prevention is important because once dementia is diagnosed, it is very difficult to slow or reverse. There is no cure,” said LaCroix.

However, because few large studies have examined device measures of movement and sitting in relation to mild cognitive impairment and dementia, much of the published research on the associations of physical activity and sedentary behavior with cognitive decline and dementia is based on self-reported measures, said first author, Steven Nguyen, Ph.D., M.P.H., postdoctoral scholar at the Herbert Wertheim School of Public Health.

For this study, the researchers sampled data from 1,277 women as part of two Women’s Health Initiative (WHI) ancillary studies — the WHI Memory Study (WHIMS) and the Objective Physical Activity and Cardiovascular Health (OPACH) study. The women wore research-grade accelerometers and went about their daily activities for up to seven days to obtain accurate measures of physical activity and sitting.

The activity trackers showed the women averaged 3,216 steps, 276 minutes in light physical activities, 45.5 minutes of moderate-to-vigorous physical activity and 10.5 hours of sitting per day. Examples of light physical activity could include housework, gardening or walking. Moderate-to-vigorous physical activity could include brisk walking.

The study findings also showed that higher amounts of sitting and prolonged sitting were not associated with higher risk of mild cognitive impairment or dementia.

Together, this information has clinical and public health importance as there is little published information on the amount and intensity of physical activity needed for a lower dementia risk, said Nguyen.

“Older adults can be encouraged to increase movement of at least moderate intensity and take more steps each day for a lower risk of mild cognitive impairment and dementia,” said Nguyen.

“The findings for steps per day are particularly noteworthy because steps are recorded by a variety of wearable devices increasingly worn by individuals and could be readily adopted.”

The authors said further research is needed among large diverse populations that include men.

Co-authors include: John Bellettiere, UC San Diego; Kathleen M. Hayden and Stephen R. Rapp, Wake Forest University School of Medicine; Chongzhi Di, Fred Hutchinson Cancer Center; Priya Palta, Columbia University Irving Medical Center; Marcia L. Stefanick, Stanford University School of Medicine; JoAnn E. Manson, Harvard Medical School; and Michael J. LaMonte, University at Buffalo — SUNY.

This research was funded, in part, by the National Institute on Aging (P01 AG052352, 5T32AG058529-03) and the National Heart, Lung, and Blood Institute (R01 HL105065). The Women’s Health Initiative was funded by the National Heart, Lung, and Blood Institute (75N92021D00001, 75N92021D00002, 75N92021D00003, 75N92021D00004, 75N92021D00005).

This work was centred around the lateral line sensing organ in African cichlid fish, but found in almost all fish species, that enables them to sense and interpret water pressures around them with enough acuity to detect external influences such as neighbouring fish, changes in water flow, predators and obstacles.

The lateral line system as a whole is distributed over the head, trunk and tail of the fish. It is comprised of mechanoreceptors (neuromasts) that are either within subdermal channels or on the surface of the skin.

Lead author Elliott Scott of the University of Bristol’s Department of Engineering Mathematics explained: “We were attempting to find out if the different areas of the lateral line — the lateral line on the head versus the lateral line on the body, or the different types of lateral line sensory units such as those on the skin, versus those under it, play different roles in how the fish is able to sense its environment through environmental pressure readings.

“We did this in a novel way, by using hybrid fish, that allowed for the natural generation of variation.”

They discovered the lateral line system around the head has the most important influence on how well fish are able to swim in a shoal, Meanwhile, the presence of more lateral line sensory units, neuromasts, that are found under the skin result in fish swimming closer together, while a greater presence of neuromasts on the skin tend to result in fish swimming further apart.

In simulation, the researchers were able to show how the mechanisms behind the lateral line work are applicable at not just the tiny scales found in actual fish, but at larger scales too. This could inspire a novel type of easily-manufactured pressure sensor for underwater robotics, particularly swarm robotics, where cost is a large factor.

Elliott said: “These findings provide a better understanding of how the lateral line informs shoaling behaviour in fish, while also contributing a novel design of inexpensive pressure sensor that could be useful on underwater robots that have to navigate in dark or murky environments.”

The team now plan to develop the sensor further and integrate it into a robotic platform to help a robot navigate underwater and demonstrate its effectiveness.

The research for this paper was funded by Engineering and Physical Sciences Research Council (EPSRC), Biotechnology and Biological Sciences Research Council (BBSRC) and the Human Frontier Science Program (HFSP).

Researchers say these findings, published in the peer-reviewed journal Alzheimer’s & Dementia: Translational Research and Clinical Interventions, may point the way to a cure.

“Many of these patients experience cognitive, behavioral and personality changes so severe that they are arrested or placed in nursing homes,” said Wouter Schievink, MD, director of the Cerebrospinal Fluid Leak and Microvascular Neurosurgery Program and professor of Neurosurgery at Cedars-Sinai. “If they have behavioral-variant frontotemporal dementia with an unknown cause, then no treatment is available. But our study shows that patients with cerebrospinal fluid leaks can be cured if we can find the source of the leak.”

Cerebrospinal fluid (CSF) circulates in and around the brain and spinal cord to help cushion them from injury. When this fluid leaks into the body, the brain can sag, causing dementia symptoms. Schievink said many patients with brain sagging — which can be detected through MRI — go undiagnosed, and he advises clinicians to take a second look at patients with telltale symptoms.

“A knowledgeable radiologist, neurosurgeon or neurologist should check the patient’s MRI again to make sure there is no evidence for brain sagging,” Schievink said.

Clinicians can also ask about a history of severe headaches that improve when the patient lies down, significant sleepiness even after adequate nighttime sleep, and whether the patient has ever been diagnosed with a Chiari brain malformation, a condition in which brain tissue extends into the spinal canal. Brain sagging, Schievink said, is often mistaken for a Chiari malformation.

Even when brain sagging is detected, the source of a CSF leak can be difficult to locate. When the fluid leaks through a tear or cyst in the surrounding membrane, it is visible on CT myelogram imaging with the aid of contrast medium.

Schievink and his team recently discovered an additional cause of CSF leak: the CSF-venous fistula. In these cases, the fluid leaks into a vein, making it difficult to see on a routine CT myelogram. To detect these leaks, technicians must use a specialized CT scan and observe the contrast medium in motion as it flows through the cerebrospinal fluid.

In this study, investigators used this imaging technique on 21 patients with brain sagging and symptoms of bvFTD, and they discovered CSF-venous fistulas in nine of those patients. All nine patients had their fistulas surgically closed, and their brain sagging and accompanying symptoms were completely reversed.

“This is a rapidly evolving field of study, and advances in imaging technology have greatly improved our ability to detect sources of CSF leak, especially CSF-venous fistula,” said Keith L. Black, MD, chair of the department of Neurosurgery and the Ruth and Lawrence Harvey Chair in Neuroscience at Cedars-Sinai. “This specialized imaging is not widely available, and this study suggests the need for further research to improve detection and cure rates for patients.”

The remaining 12 study participants, whose leaks could not be identified, were treated with nontargeted therapies designed to relieve brain sagging, such as implantable systems for infusing the patient with CSF. However, only three of these patients experienced relief from their symptoms.

“Great efforts need to be made to improve the detection rate of CSF leak in these patients,” Schievink said. “We have developed nontargeted treatments for patients where no leak can be detected, but as our study shows, these treatments are much less effective than targeted, surgical correction of the leak.”

Details of this lifestyle switch could provide new insights into the regulation of algal bloom dynamics and its impact on large-scale biogeochemical processes in marine environments.

Single-celled algae, known as phytoplankton, form oceanic blooms which are responsible for around half of the photosynthesis that occurs on Earth, and form the basis of marine food webs. Therefore, understanding the factors controlling phytoplankton growth and death is crucial to maintaining a healthy marine ecosystem. Marine bacteria from the Roseobacter group are known to pair up and coexist with phytoplankton in a mutually beneficial interaction. The phytoplankton provide the Roseobacter with organic matter useful for bacterial growth, such as sugar and amino acids, and the Roseobacter in return provides B-vitamins and growth-promoting factors.

However, recent studies have revealed that Roseobacters undergo a lifestyle switch from coexistence to pathogenicity, where they kill their phytoplankton hosts. A chemical compound called DMSP is produced by the algae and is hypothesised to play a role in this switch.

“We have previously identified that the Roseobacter Sulfitobacter D7 displays a lifestyle switch when interacting with the phytoplankter Emiliania huxleyi,” states first author Noa Barak-Gavish, a PhD graduate in the Department of Plant and Environmental Sciences, Weizmann Institute of Science, Israel. “However, our knowledge about the factors that determine this switch was still limited.”

To characterise this lifestyle switch, Barak-Gavish and colleagues performed a transcriptomics experiment, allowing them to compare the genes that are differentially expressed by Sulfitobacter D7 in coexistence or pathogenicity stages.

Their experimental setup demonstrated that Sulfitobacter D7 grown in a pathogenicity-inducing medium have a higher expression of transporters for metabolites such as amino acids and carbohydrates than those grown in a coexistence medium. These transporters serve to maximise the uptake of metabolites released from dying Emiliania huxleyi (E. huxleyi). Furthermore, in pathogenic Sulfitobacter D7, the team observed an increased activation of flagellar genes that are responsible for the movement of the bacteria. These two factors allow Sulfitobacter D7 to utilise an ‘eat-and-run’ strategy, where they beat competitors to the material released upon E. huxleyi cell death and swim away in search of another suitable host.

The team confirmed the role of DMSP in bringing about the switch to this killer behaviour by mapping the genes activated in Sulfitobacter D7 in response to the presence of DMSP and other algae-derived compounds. However, when only DMSP was present, the lifestyle switch did not occur. This implies that, although DMSP mediates the lifestyle switch, it is also dependent on the presence of other E. huxleyi-derived infochemicals — compounds that are produced and used by organisms to communicate. DMSP is an infochemical produced by many phytoplankton, so it is likely that the other required infochemicals allow the bacteria to recognise a specific phytoplankton host. In natural environments, where many different microbial species exist together, this specificity would ensure that bacteria only invests in altering gene expression and its metabolism when the correct algal partner is present.

The study also uncovers the role of algae-derived benzoate in Sulfitobacter D7 and E. huxleyi interactions. Even in high concentrations of DMSP, benzoate functions to maintain the coexistence lifestyle. Benzoate is an efficient growth factor and is provided by E. huxleyi to Sulfitobacter D7 during coexistence. The authors propose that as long as Sulfitobacter D7 benefits from coexistence by receiving materials for growth, it will maintain the mutualistic interaction. When less benzoate and other growth substrates are provided, the bacteria undergoes the lifestyle switch and kills its phytoplankton host, swallowing up any remaining useful materials.

The exact mechanism of Sulfitobacter D7 pathogenicity against E. huxleyi remains to be discovered, and the authors call for further work in this area. The cellular machinery Type 2 secretion system — a complex that many bacteria use to move materials across their cell membrane — is more prevalent in Sulfitobacter D7 compared to other Roseobacters, hinting at a unique method of pathogenicity that requires further investigation.

“Our work provides a contextual framework for the switch from coexistence to pathogenicity in Roseobacter-phytoplankton interactions,” concludes senior author Assaf Vardi, a Professor in the Department of Plant and Environmental Sciences, Weizmann Institute of Science. “These interactions are an underappreciated component in the regulation of algal bloom dynamics and further study in this area could provide insights into their impact on the fate of carbon and sulfur in the marine environment.”

Scientists at the University of Reading studied the relative fortunes of 50 species of large carnivores worldwide over the past fifty years. They found social and economic factors, such as quality of life, were more closely associated with declines of large carnivore species, than purely environmental features like habitat loss.

The first-of-its-kind study suggests that the best way to save carnivores, such as lynx, bears and lions, is to encourage a sustainable model of social and economic development, rather than focusing only on issues such as climate change. As people get richer, their tolerance for big cats and other carnivores increases.

Rapid declines

Dr Thomas Frederick Johnson, who led the study while based at Reading, said: “Our habitat and climate has become degraded and chaotic to make-way for rapid economic development. We know this has driven biodiversity declines, but our research found that this economic development is causing far more extreme declines than anyone expected and imagined.

“In the midst of rapid development, people appear to become less tolerant of carnivores, conflicts explode, and we suspect that incidences of poaching and persecution rocket.

“The decline of large carnivores is stark. Lions and tigers are already absent from more than 90% of their historic range. At home, many of the UK carnivore species, such as lynx, wolf and bear have already been hunted into extinction.”

‘Turning point’

The study, published in Nature Communications in partnership with the UK Centre for Ecology & Hydrology and the Argentinian Instituto de Biología Subtropical, involved the research team examining how changes to the social and economic system could promote carnivore recoveries.

While rapid economic development pushes species to the brink of extinction, it has also delivered enormous improvements in our quality of life. However, analysis from Dr Johnson and his fellow ecologists suggests that once people achieve a high quality of life and economic development slows, a turning point is reached and persecuted species have an opportunity to recover.

The researchers suggest the recovery is partly linked to improved habitat protection in advanced economies, but also a more harmonious relationship between people and carnivores. What would once have been considered a dangerous pest is now being recognised as an important component of our ecosystems and culture.

The resurgence of large carnivores can already be seen in western Europe, where an improved quality of life and slower economic development has allowed populations of grey wolves to rocket 1,800% since the 1960s.

Dr Johnson said: “This gives us hope that we can restore our lost ecosystems and we could one day see lost carnivores return to British shores. But we also need to think about how we can save wildlife in countries currently experiencing rapid growth, where species extinctions are likely.

“Our results suggest that a slower, more sustainable, economic model can protect carnivore populations, but this also risks locking people into poverty for longer. We urgently need to develop solutions that can support both biodiversity and people, and perhaps the world’s advanced economies need to offer more financial aid to protect our global biodiversity.”