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Uncovering the brain’s ability to compensate for age-related cognitive decline

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A new study has revealed that our brains can compensate for age-related cognitive decline by recruiting other areas to help with brain function and maintain cognitive performance.

As we age, our brain gradually atrophies, losing nerve cells and connections. This can lead to a decline in brain function.

It is not yet fully understood why some people appear to maintain better brain function than others, and how we can protect ourselves from cognitive decline.

A widely accepted notion is that some people’s brains are able to compensate for the deterioration in brain tissue by recruiting other areas of the brain to help perform tasks. While brain imaging studies have shown that the brain does recruit other areas, until now it has not been clear whether this makes any difference to performance on a task, or whether it provides any additional information about how to perform that task.

In a study published in the journal eLife, a team led by scientists at the University of Cambridge in collaboration with the University of Sussex have shown that when the brain recruits other areas, it improves performance specifically in the brains of older people.

Study lead Dr Kamen Tsvetanov, an Alzheimer’s Society Dementia Research Leader Fellow in the Department of Clinical Neurosciences, University of Cambridge, stated: “Our ability to solve abstract problems is a sign of so-called ‘fluid intelligence’, but as we get older, this ability begins to show significant decline.

“Some people manage to maintain this ability better than others. We wanted to ask why that was the case – are they able to recruit other areas of the brain to overcome changes in the brain that would otherwise be detrimental?”

Imaging studies

Brain imaging studies have shown that fluid intelligence tasks engage the ‘multiple demand network’ (MDN), a brain network involving regions both at the front and rear of the brain, but its activity decreases with age.

To see whether the brain compensated for this decrease in activity, the Cambridge team looked at imaging data from 223 adults between 19 and 87 years of age who had been recruited by the Cambridge Centre for Ageing & Neuroscience (Cam-CAN).

The volunteers were asked to identify the odd-one-out in a series of puzzles of varying difficulty while lying in a functional magnetic resonance imaging (fMRI) scanner, so that the researchers could look at patterns of brain activity by measuring changes in blood flow.

As anticipated, in general the ability to solve the problems decreased with age. The MDN was particularly active, as were regions of the brain involved in processing visual information.

When the team analysed the images further using machine-learning, they found two areas of the brain that showed greater activity in the brains of older people, and also correlated with better performance on the task.

These areas were the cuneus, at the rear of the brain, and a region in the frontal cortex. But of the two, only activity in the cuneus region was related to performance of the task more strongly in the older than younger volunteers, and contained extra information about the task beyond the MDN.

Although it is not clear exactly why the cuneus should be recruited for this task, the researchers point out that this brain region is usually good at helping us stay focused on what we see. Older adults often have a harder time briefly remembering information that they have just seen, like the complex puzzle pieces used in the task. The increased activity in the cuneus might reflect a change in how often older adults look at these pieces, as a strategy to make up for their poorer visual memory.

Dr Ethan Knights from the Medical Research Council Cognition and Brain Sciences Unit at Cambridge said: “Now that we’ve seen this compensation happening, we can start to ask questions about why it happens for some older people, but not others, and in some tasks, but not others.

“Is there something special about these people – their education or lifestyle, for example – and if so, is there a way we can intervene to help others see similar benefits?”

Dr Alexa Morcom from the University of Sussex’s School of Psychology and Sussex Neuroscience research centre said: “This new finding also hints that compensation in later life does not rely on the multiple demand network as previously assumed, but recruits areas whose function is preserved in ageing.”

The research was supported by the Medical Research Council, the Biotechnology and Biological Sciences Research Council, the European Union’s Horizon 2020 research and innovation programme, the Guarantors of Brain, and the Alzheimer’s Society.

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Gut microbes from aged mice induce inflammation in young mice

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Findings from a new study suggest that changes to the gut microbiome play a role in the systemwide inflammation that often occurs with ageing.

When scientists transplanted the gut microbes of aged mice into young “germ-free” mice — raised to have no gut microbes of their own — the recipient mice experienced an increase in inflammation that parallels inflammatory processes associated with ageing in humans. Young germ-free mice transplanted with microbes from other young mice had no such increase.

Published in Aging Cell, the study also found that antibiotics caused longer-lasting disruptions in the gut microbiomes of aged mice than in young mice.

“There’s been a growing consensus that ageing is associated with a progressive increase in chronic low-grade inflammation,” said Jacob Allen, a professor of kinesiology and community health at the University of Illinois Urbana-Champaign who led the new research with Thomas Buford, a professor of medicine at the University of Alabama at Birmingham.

“And there’s a kind of debate as to what drives this, what is the major cause of the ageing-induced inflammatory state. We wanted to understand if the functional capacity of the microbiome was changing in a way that might contribute to some of the inflammation that we see with ageing.”

Previous studies have found associations between age-related changes in the microbial composition of the gut and chronic inflammatory diseases such as Parkinson’s disease and Alzheimer’s disease. Some studies have linked microbial metabolism to an individual’s susceptibility to other health conditions, including obesity, irritable bowel syndrome and heart disease. Age-related changes in the gut microbiome also may contribute to the so-called leaky gut problem, the researchers said.

“Microbiome patterns in aged mice are strongly associated with signs of bacterial-induced barrier disruption and immune infiltration,” they wrote.

“The things that are in our gut are supposed to be kept separate from the rest of our system,” Buford said. “If they leak out, our immune system is going to recognize them. And so then the question was: ‘Is that a source of inflammation?’”

Many studies have compared the relative abundance and diversity of species of microbes in the gut, offering insight into some of the major groups that contribute to health or disease. But sequencing even a portion of the microbes in the gut is expensive and the results can be difficult to interpret, Allen said. That is why he and his colleagues focused on microbial function — specifically, how the gut microbiomes of ageing mice might spur an immune response.

The team focused on toll-like receptors, molecules that mediate inflammatory processes throughout the body. TLRs sit in cellular membranes and sample the extracellular environment for signs of tissue damage or infection. If a TLR encounters a molecule associated with a potential pathogen — for example, a lipopolysaccharide component of a gram-negative bacterium — it activates an innate immune response, calling in pro-inflammatory agents and other molecules to fight the infection.

The researchers first evaluated whether the colonic contents of young and aged mice were likely to promote TLR signalling. They found that microbes from aged mice were more likely than those from young mice to activate TLR4, which can sense lipopolysaccharide components of bacterial cell walls. A different receptor, TLR5, was not affected differently in aged or young mice. TLR5 senses a different bacterial component, known as flagellin.

Young germ-free mice transplanted with the microbes of aged mice also experienced higher inflammatory signalling and increased levels of lipopolysaccharides in the blood after the transplants, the team found.

This finding provides “a direct link between ageing-induced shifts in microbiota immunogenicity and host inflammation,” the researchers wrote.

In other experiments, the team treated mice with broad-spectrum antibiotics and tracked changes in the microbiomes during treatment and for seven days afterward.

“One of the most interesting questions for me was what microbes come back immediately after the treatment with antibiotics ends,” Buford said. And in the mice with aged microbiota in their guts, “these opportunistic pathogens were the most quick to come back.”

“It appears that as we age our microbiome might be less resilient to antibiotic challenges,” Allen said. “This is important because we know that in the U.S. and other Western societies, we’re increasingly exposed to more antibiotics as we age.”

The study is an important step toward understanding how age-related microbial changes in the gut may affect long-term health and inflammation, the researchers said.

Co-authors of the study also included Illinois postdoctoral researcher Elisa Caetano-Silva; U. of I. Ph.D. student Akriti Shrestha; National Children’s Hospital research scientist Michael Bailey; and Jeffrey Woods, the director of the Center on Health, Aging and Disability at Illinois.

Allen also is a professor of nutritional sciences at Illinois and an affiliate of the Carl R. Woese Institute for Genomic Biology at the U. of I.

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Evening exercise benefits elderly hypertensives

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Evening exercise benefits elderly hypertensives

A study conducted at the University of São Paulo with 23 volunteers found that aerobic exercise performed in the evening benefits elderly hypertensives more than morning exercise.

Aerobic training is known to regulate blood pressure more effectively when practiced in the evening than in the morning.

Researchers who conducted a study of elderly patients at the University of São Paulo’s School of Physical Education and Sports (EEFE-USP) in Brazil concluded that evening exercise is better for blood pressure regulation thanks to improved cardiovascular control by the autonomic nervous system via a mechanism known as baroreflex sensitivity.

Leandro Campos de Brito, first author of the article, commented: “There are multiple mechanisms to regulate blood pressure, and although morning training was beneficial, only evening training improved short-term control of blood pressure by enhancing baroreflex sensitivity.

“This is important because baroreflex control has a positive effect on blood pressure regulation, and there aren’t any medications to modulate the mechanism.”

In the study, 23 elderly patients diagnosed and treated for hypertension were randomly allocated into two groups: morning training and evening training. Both groups trained for ten weeks on a stationary bicycle at moderate intensity, with three 45-minute sessions per week.

Key cardiovascular parameters were analysed, such as systolic and diastolic blood pressure, and heart rate after ten minutes’ rest. The data was collected before and at least three days after the volunteers completed the ten weeks of training.

The researchers also monitored mechanisms pertaining to the autonomic nervous system, which controls breathing, heart rate, blood pressure, digestion, and other involuntary bodily functions, such as muscle sympathetic nerve activity, which regulates peripheral blood flow via contraction and relaxation of blood vessels in muscle tissue, and sympathetic baroreflex sensitivity, assessing control of blood pressure via alterations to muscle sympathetic nerve activity.

In the evening training group, all four parameters analysed were found to improve: systolic and diastolic blood pressure, sympathetic baroreflex sensitivity, and muscle sympathetic nerve activity. In the morning training group, no improvements were detected in muscle sympathetic nerve activity, systolic blood pressure or sympathetic baroreflex sensitivity.

“Evening training was more effective in terms of improving cardiovascular autonomic regulation and lowering blood pressure. This can be partly explained as due to an improvement in baroreflex sensitivity and a reduction of muscle sympathetic nerve activity, which increased in the evening. For now, all we know is that baroreflex control is the decisive factor, from the cardiovascular standpoint at least, to make evening training more beneficial than morning training, since it induces the other benefits analysed. However, much remains to be done in this regard in order to obtain a better understanding of the mechanisms involved,” said Brito, who is currently a professor at Oregon Health & Science University’s Oregon Institute of Occupational Health Sciences in the United States, and continues to investigate the topic via circadian rhythm studies.

Baroreflex sensitivity regulates each heartbeat interval and controls autonomic activity throughout the organism.

“It’s a mechanism that involves sensitive fibres and deformations in the walls of arteries in specific places, such as the aortic arch and carotid body. When blood pressure falls, this region warns the brain region that controls the autonomic nervous system, which in turn signals the heart to beat faster and tells the arteries to contract more strongly. If blood pressure rises, it warns the heart to beat more slowly and tells the arteries to contract less. In other words, it modulates arterial pressure beat by beat,” Brito explained.

In previous studies, the EEFE-USP research group showed that evening aerobic training reduced blood pressure more effectively than morning training in hypertensive men (read more at: agencia.fapesp.br/34194), and that the more effective response to evening training in terms of blood pressure control was accompanied by a greater reduction in systemic vascular resistance and systolic pressure variability (read more at: agencia.fapesp.br/37432).

“Replication of the results obtained in previous studies and in different groups of hypertensive patients, associated with the use of more precise techniques to evaluate the main outcomes, has strengthened our conclusion that aerobic exercise performed in the evening is more beneficial to the autonomic nervous system in patients with hypertension. This can be especially important for those with resistance to treatment with medication,” Brito said.

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Revolutionising cancer treatment: intracellular protein delivery using hybrid nanotubes

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Revolutionising cancer treatment: intracellular protein delivery using hybrid nanotubes

A new hybrid nanotube stamp system has been developed which revolutionises precision medicine with high efficiency and cell viability rates for cancer treatment.

Precision medicine and targeted therapies are gaining traction for their ability to tailor treatments to individual patients while minimising adverse effects. Conventional methods, such as gene transfer techniques, show promise in delivering therapeutic genes directly to cells to address various diseases.

However, these methods face significant drawbacks, hindering their efficacy and safety. Intracellular protein delivery offers a promising approach for developing safer, more targeted, and effective therapies. By directly transferring proteins into target cells, this method circumvents issues such as silencing during transcription and translation and the risk of undesirable mutations from DNA insertion. Additionally, intracellular protein delivery allows for precise distribution of therapeutic proteins within target cells without causing toxicity.

A group of researchers led by Professor Takeo Miyake at Waseda University, Japan in collaboration with the Mikawa Group at the RIKEN Institute have now developed a hybrid nanotube stamp system for intracellular delivery of proteins. This innovative technique enables the simultaneous delivery of diverse cargoes, including calcein dye, lactate oxidase (LOx) enzyme, and ubiquitin (UQ) protein, directly into adhesive cells for cancer treatment.

The researchers explored the therapeutic potential of delivering LOx enzyme for cancer treatment. “Through our innovative stamp system, we successfully delivered LOx into both healthy mesenchymal stem cells (MSC) and cancerous HeLa cells. While MSC cells remained unaffected, we observed significant cell death in HeLa cancer cells following LOx treatment with viabilities decreasing over time. Our findings highlight the promising efficacy of intracellularly delivered LOx in selectively targeting and killing cancer cells, while sparing healthy cells, offering a targeted therapeutic strategy for cancer treatment,” explains Miyake.

Finally, the team successfully delivered 15N isotope-labeled UQ proteins into HeLa cells using the HyNT stamp system. This delivery allowed for the analysis of complex protein structures and interactions within the cells. In addition, optical and fluorescence imaging confirmed the presence of delivered UQ in HeLa cells, and nuclear magnetic resonance spectroscopy matched the intracellular UQ protein concentration with that of a solution containing 15N-labeled UQ. These results demonstrate the effectiveness of the stamp system in delivering target proteins for subsequent analysis.

The results demonstrate the remarkable capability of the HyNT stamp system in delivering LOx and UQ into a substantial number of adhesive cells, as required for regenerative medicine applications. The system achieved a notably high delivery efficiency of 89.9%, indicating its effectiveness in transporting therapeutic proteins into the target cells with precision. Moreover, the cell viability rate of 97.1% highlights the system’s ability to maintain the health and integrity of the treated cells throughout the delivery process.

The HyNT stamp system offers transformative potential in intracellular protein delivery, with applications spanning from cancer treatment to molecular analysis. Beyond medicine, its versatility extends to agriculture and food industries, promising advancements in crop production and food product development. With precise cell manipulation and efficient delivery, the HyNT stamp system is poised to revolutionize biomedical research, clinical practice, and diverse industries, paving the way for personalized interventions and shaping the future of modern medicine.

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