Posts tagged aging
Articles and news from the latest research reports.
Focus on naturally occurring protein to tackle dementia
Scientists at the University of Warwick have provided the first evidence that the lack of a naturally occurring protein is linked to early signs of dementia.
Published in Nature Communications, the research found that the absence of the protein MK2/3 promotes structural and physiological changes to cells in the nervous system. These changes were shown to have a significant correlation with early signs of dementia, including restricted learning and memory formation capabilities.
An absence of MK2/3, in spite of the brain cells (neurons) having significant structural abnormalities, did not prevent memories being formed, but did prevent these memories from being altered.
The results have led the researchers to call for greater attention to be paid to studying MK2/3.
Lead researcher and author Dr Sonia Corrêa says that “Understanding how the brain functions from the sub-cellular to systems level is vital if we are to be able to develop ways to counteract changes that occur with ageing.
“By demonstrating for the first time that the MK2/3 protein, which is essential for neuron communication, is required to fine-tune memory formation this study provides new insight into how molecular mechanisms regulate cognition”.
Neurons can adapt memories and make them more relevant to current situations by changing the way they communicate with other cells.
Information in the brain is transferred between neurons at synapses using chemicals (neurotransmitters) released from one (presynaptic) neuron which then act on receptors in the next (postsynaptic) neuron in the chain.
MK2/3 regulates the shape of spines in properly functioning postsynaptic neurons. Postsynaptic neurons with MK2/3 feature wider, shorter spines (Fig.1) than those without (Fig2).
The researchers found that change, caused by MK2/3’s absence, in the spine’s shape restricts the ability of neurons to communicate with each other, leading to alterations in the ability to acquire new memories.
“Deterioration of brain function commonly occurs as we get older but, as result of dementia or other neurodegenerative diseases, it can occur earlier in people’s lives”, says Dr Corrêa. “For those who develop the early signs of dementia it becomes more difficult for them to adapt to changes in their life, including performing routine tasks.
“For example, washing the dishes; if you have washed them by hand your whole life and then buy a dishwasher it can be difficult for those people who are older or have dementia to acquire the new memories necessary to learn how to use the machine and mentally replace the old method of washing dishes with the new. The change in shape of the postsynaptic neuron due to absence of MK2/3 is strongly correlated with this inability to acquire the new memories”.
Dr Corrêa argues that “Given their vital role in memory formation, MK2/3 pathways are important potential pharmaceutical targets for the treatment of cognitive deficits associated with ageing and dementia.”
Train your heart to protect your mind
Exercising to improve our cardiovascular strength may protect us from cognitive impairment as we age, according to a new study by researchers at the University of Montreal and its affiliated Institut universitaire de gératrie de Montréal Research Centre. “Our body’s arteries stiffen with age, and the vessel hardening is believed to begin in the aorta, the main vessel coming out of the heart, before reaching the brain. Indeed, the hardening may contribute to cognitive changes that occur during a similar time frame,” explained Claudine Gauthier, first author of the study. “We found that older adults whose aortas were in a better condition and who had greater aerobic fitness performed better on a cognitive test. We therefore think that the preservation of vessel elasticity may be one of the mechanisms that enables exercise to slow cognitive aging.”
The researchers worked with 31 young people between the ages of 18 and 30 and 54 older participants aged between 55 and 75. This enabled the team to compare the older participants within their peer group and against the younger group who obviously have not begun the aging processes in question. None of the participants had physical or mental health issues that might influence the study outcome. Their fitness was tested by exhausting the participants on a workout machine and determining their maximum oxygen intake over a 30 second period. Their cognitive abilities were assessed with the Stroop task. The Stroop task is a scientifically validated test that involves asking someone to identify the ink colour of a colour word that is printed in a different colour (e.g. the word red could be printed in blue ink and the correct answer would be blue). A person who is able to correctly name the colour of the word without being distracted by the reflex to read it has greater cognitive agility.
The participants undertook three MRI scans: one to evaluate the blood flow to the brain, one to measure their brain activity as they performed the Stroop task, and one to actually look at the physical state of their aorta. The researchers were interested in the brain’s blood flow, as poorer cardiovascular health is associated with a faster pulse wave,at each heartbeat which in turn could cause damage to the brain’s smaller blood vessels. “This is first study to use MRI to examine participants in this way,” Gauthier said. “It enabled us to find even subtle effects in this healthy population, which suggests that other researchers could adapt our test to study vascular-cognitive associations within less healthy and clinical populations.”
The results demonstrated age-related declines in executive function, aortic elasticity and cardiorespiratory fitness, a link between vascular health and brain function, and a positive association between aerobic fitness and brain function. “The link between fitness and brain function may be mediated through preserved cerebrovascular reactivity in periventricular watershed areas that are also associated with cardiorespiratory fitness,” Gauthier said. “Although the impact of fitness on cerebral vasculature may however involve other, more complex mechanisms, overall these results support the hypothesis that lifestyle helps maintain the elasticity of arteries, thereby preventing downstream cerebrovascular damage and resulting in preserved cognitive abilities in later life.”
Research helps explain why elderly have trouble sleeping
As people grow older, they often have difficulty falling asleep and staying asleep, and tend to awaken too early in the morning. In individuals with Alzheimer’s disease, this common and troubling symptom of aging tends to be especially pronounced, often leading to nighttime confusion and wandering.
Now, a study led by researchers at Beth Israel Deaconess Medical Center (BIDMC) and the University of Toronto/Sunnybrook Health Sciences Center helps explain why sleep becomes more fragmented with age. Reported online today in the journal Brain, the new findings demonstrate for the first time that a group of inhibitory neurons, whose loss leads to sleep disruption in experimental animals, are substantially diminished among the elderly and individuals with Alzheimer’s disease, and that this, in turn, is accompanied by sleep disruption.
"On average, a person in his 70s has about one hour less sleep per night than a person in his 20s," explains senior author Clifford B. Saper, MD, PhD, Chairman of Neurology at BIDMC and James Jackson Putnam Professor of Neurology at Harvard Medical School. "Sleep loss and sleep fragmentation is associated with a number of health issues, including cognitive dysfunction, increased blood pressure and vascular disease, and a tendency to develop type 2 diabetes. It now appears that loss of these neurons may be contributing to these various disorders as people age."
In 1996, the Saper lab first discovered that the ventrolateral preoptic nucleus, a key cell group of inhibitory neurons, was functioning as a “sleep switch” in rats, turning off the brain’s arousal systems to enable animals to fall asleep. “Our experiments in animals showed that loss of these neurons produced profound insomnia, with animals sleeping only about 50 percent as much as normal and their remaining sleep being fragmented and disrupted,” he explains.
A group of cells in the human brain, the intermediate nucleus, is located in a similar location and has the same inhibitory neurotransmitter, galanin, as the vetrolateral preoptic nucleus in rats. The authors hypothesized that if the intermediate nucleus was important for human sleep and was homologous to the animal’s ventrolateral preoptic nucleus, then it may also similarly regulate humans’ sleep-wake cycles.
In order to test this hypothesis, the investigators analyzed data from the Rush Memory and Aging Project, a community-based study of aging and dementia which began in 1997 and has been following a group of almost 1,000 subjects who entered the study as healthy 65-year-olds and are followed until their deaths, at which point their brains are donated for research.
"Since 2005, most of the subjects in the Memory and Aging Project have been undergoing actigraphic recording every two years. This consists of their wearing a small wristwatch-type device on their non-dominant arm for seven to 10 days," explains first author Andrew S. P. Lim, MD, of the University of Toronto and Sunnybrook Health Sciences Center and formerly a member of the Saper lab. The actigraphy device, which is waterproof, is worn 24 hours a day and thereby monitors all movements, large and small, divided into 15-second intervals. "Our previous work had determined that these actigraphic recordings are a good measure of the amount and quality of sleep," adds Lim.
The authors examined the brains of 45 study subjects (median age at death, 89.2), identifying ventrolateral preoptic neurons by staining the brains for the neurotransmitter galanin. They then correlated the actigraphic rest-activity behavior of the 45 individuals in the year prior to their deaths with the number of remaining ventrolateral preoptic neurons at autopsy.
"We found that in the older patients who did not have Alzheimer’s disease, the number of ventrolateral preoptic neurons correlated inversely with the amount of sleep fragmentation," says Saper. "The fewer the neurons, the more fragmented the sleep became." The subjects with the largest amount of neurons (greater than 6,000) spent 50 percent or more of total rest time in the prolonged periods of non-movement most likely to represent sleep while subjects with the fewest ventrolateral preoptic neurons (less than 3,000) spent less than 40 percent of total rest time in extended periods of rest. The results further showed that among Alzheimer’s patients, most sleep impairment seemed to be related to the number of ventrolateral preoptic neurons that had been lost.
"These findings provide the first evidence that the ventrolateral preoptic nucleus in humans probably plays a key role in causing sleep, and functions in a similar way to other species that have been studied," says Saper. "The loss of these neurons with aging and with Alzheimer’s disease may be an important reason why older individuals often face sleep disruptions. These results may, therefore, lead to new methods to diminish sleep problems in the elderly and prevent sleep-deprivation-related cognitive decline in people with dementia."
Targeted brain training may help you multitask better
The area of the brain involved in multitasking and ways to train it have been identified by a research team at the IUGM Institut universitaire de gériatrie de Montréal and the University of Montreal. The research includes a model to better predict the effectiveness of this training. Cooking while having a conversation, watching a movie while browsing the Web, or driving while listening to a radio show – multitasking is an essential skill in our daily lives. Unfortunately, it decreases with age, which makes it harder for seniors to keep up, causes them stress, and decreases their confidence. Many commercial software applications promise to improve this ability through exercises. But are these exercises truly effective, and how do they work on the brain? The team addresses these issues in two papers published in AGE and PLOS ONE.
Targeted Action for a Specific Result
The findings are important because they may help scientists develop better targeted cognitive stimulation programs or improve existing training programs. Specialists sometimes question the usefulness of exercises that may be ineffective simply because they are poorly structured. “To improve your cardiovascular fitness, most people know you need to run laps on the track and not work on your flexibility. But the way targeted training correlates to cognition has been a mystery for a long time. Our work shows that there is also an association between the type of cognitive training performed and the resulting effect. This is true for healthy seniors who want to improve their attention or memory and is particularly important for patients who suffer from damage in specific areas of the brain. We therefore need to better understand the ways to activate certain areas of the brain and target this action to get specific results,” explained Sylvie Belleville, who led the research.
Researchers are now better able to map these effects on the functioning of very specific areas of the brain. Will we eventually be able to adapt the structure of our brains through highly targeted training? “We have a long road ahead to get to that point, and we don’t know for sure if that would indeed be a desirable outcome. However, our research findings can be used right away to improve the daily lives of aging adults as well as people who suffer from brain damage,” Dr. Belleville said.
The Right Combination of Plasticity and Attentional Control
In one of the studies, 48 seniors were randomly allocated to training that either worked on plasticity and attentional control or only involved simple practice. The researchers used functional magnetic resonance imaging to evaluate the impact of this training on various types of attentional tasks and on brain function. The team showed that training on plasticity and attentional control helped the participants develop their ability to multitask. However, performing two tasks simultaneously was not what improved this skill. For the exercises, the research participants instead had to modulate the amount of attention given to each task. They were first asked to devote 80% of their attention to task A and 20% to task B and then change the ratio to 50:50 or 20:80. This training was the only type that increased functioning in the middle prefrontal region, or the area known to be responsible for multitasking abilities and whose activation decreases with age. The researchers used this data to create a predictive model of the effects of cognitive training on the brain based on the subjects’ characteristics.
(Source: eurekalert.org)
Music to your ears?
Many people listen to loud music without realizing that this can affect their hearing. This could lead to difficulties in understanding speech during age-related hearing loss which affects up to half of people over the age of 65.
New research led by the University of Leicester has examined the cellular mechanisms that underlie hearing loss and tinnitus triggered by exposure to loud sound.
It has demonstrated that physical changes in myelin itself -the coating of the auditory nerve carrying sound signals to the brain – affect our ability to hear.
Dr Martine Hamann, Lecturer in Neurosciences at the University of Leicester, said: “People who suffer from hearing loss have difficulties in understanding speech, particularly when the environment is noisy and when other people are talking nearby.
“Understanding speech relies on fast transmission of auditory signals. Therefore it is important to understand how the speed of signal transmission gets decreased during hearing loss. Understanding these underlying phenomena means that it could be possible to find medicines to improve auditory perception, specifically in noisy backgrounds.”
The research, funded by Action on Hearing Loss, and led by Leicester, was done in collaboration with Dr Angus Brown of the University of Nottingham. The research, Computational modelling of the effects of auditory nerve dysmyelination is published in Frontiers in Neuroanatomy.
Dr Ralph Holme, Head of Biomedical Research at Action on Hearing Loss, the only UK charity dedicated to funding research into hearing loss said: “There is an urgent need for effective treatments to prevent hearing loss - a condition that affects 10 million people in the UK and all too often isolates people from friends and family. This research further increases our understanding of the biological consequences of exposure to loud noise. Knowledge that we hope will lead to effective treatments for hearing loss within a generation.”
In previous research, researchers have shown that after exposure to loud sounds leading to hearing loss, the myelin coat surrounding the auditory nerve becomes thinner. An important property of auditory signal transmission consists of electrical signals “jumping” from one myelin domain to the other. Those domains, called Nodes of Ranvier, become elongated after exposure to loud sound.
Dr Hamann said: “Although we showed that transmission of auditory signals (electrical signals transmitted along the auditory nerve) was slowed down after exposure to loud sound leading to hearing loss, the question remained: Is this due to the actual change of the physical properties of the myelin or is it due to the redistribution of channels occurring subsequent to those changes?
“This work is a theoretical work whereby we tested the hypothesis that myelin was the prime reason for the decreased signal transmission. We simulated how physical changes to the myelin and/or redistribution of channels influenced the signal transmission along the auditory nerve. We found that the redistribution of channels had only small effect on the conduction velocity whereas physical changes to myelin were primarily responsible for the effects.”
The research has shown for the first time the closer links between a deficit in the “myelin” sheath surrounding the auditory nerve and hearing loss. “This research is innovative because data modelling (simulations) was used on previous morphological data and assessed that physical changes to the myelin coat were the principal cause of the deficit,” said Dr Hamman.
“We have come closer to understanding the reasons behind deficits in auditory perception. This means that we can also get closer to target those deficits, for example by promoting myelin repair after acoustic trauma or during age related hearing loss.”
Dr Hamann said the work will help prevention as well as progression into finding appropriate cures for hearing loss and possibly tinnitus developing from hearing loss.
“The sense of achievement comes from the fact that it could help ageing people to better understand their relatives on the phone,” said Dr Hamann.
The next step is to test drugs that could promote myelin repair and improve hearing after hearing loss.
(Source: www2.le.ac.uk)
Taking the Pulse of Aging: Researchers Map the Pulse Pressure and Elasticity of Arteries in the Brain
Researchers at the Beckman Institute at the University of Illinois at Urbana-Champaign have developed a new technique that can noninvasively image the pulse pressure and elasticity of the arteries of the brain, revealing correlations between arterial health and aging.
Brain artery support, which makes up the cerebrovascular system, is crucial for healthy brain aging and preventing diseases like Alzheimer’s and other forms of dementia.
The researchers, led by Monica Fabiani and Gabriele Gratton, psychology professors in the Cognitive Neuroscience Group, routinely record optical imaging data by shining near-infrared light into the brain to measure neural activity. Their idea to measure pulse pressure through optical imaging came from observing in previous studies that the arterial pulse produced strong signals in the optical data, which they normally do not use to study brain function. Realizing the value in this overlooked data, they launched a new study that focused on data from 53 participants aged 55-87 years.
“When we image the brain using our optical methods, we usually remove the pulse as an artifact—we take it out in order to get to other signals from the brain,” said Fabiani. “But we are interested in aging and how the brain changes with other bodily systems, like the cardiovascular system. When thinking about this, we realized it would be useful to measure the cerebrovascular system as we worry about cognition and brain physiology.”
The initial results using this new technique find that arterial stiffness is directly correlated with cardiorespiratory fitness: the more fit people are, the more elastic their arteries. Because arterial stiffening is a cause of reduced brain blood flow, stiff arteries can lead to a faster rate of cognitive decline and an increased chance of stroke, especially in older adults.
Using this method, the researchers were able to collect additional, region-specific data.
“In particular, noninvasive optical methods can provide estimates of arterial elasticity and brain pulse pressure in different regions of the brain, which can give us clues about the how different regions of the brain contribute to our overall health,” said Gratton. “For example, if we found that a particular artery was stiff and causing decreased blood flow to and loss of brain cells in a specific area, we might find that the damage to this area is also associated with an increased likelihood of certain psychological and cognitive issues.”
The researchers are investigating ways to use this technique to measure arterial stiffness across different age groups and specific cardiovascular or stress levels. High levels of stress, especially over a long amount of time, may affect arterial health, according to the researchers.
“This is just the beginning of what we’re able to explore with this technique. We’re looking at other age groups, and in the future we intend to study people with varying levels of long-term stress,” said Fabiani. “When people are stressed for long periods of time, like if they’re caring for a sick parent, stress might generate vasoconstriction and higher blood pressure, with significant consequences for arterial function in the brain. We are interested in knowing whether this may be an important factor leading to arterial stiffness.”
The researchers are also able to gather information about pulse transit time, or how long it takes the blood to flow through the brain’s arteries, and visualize large arteries running along the brain surface.
“Our goal is to find more information about what causes arterial stiffness, and how regional arterial stiffness can lead to specific health problems. Our findings continue to bolster the idea that an important key to aging well is having good cerebrovascular health,” said Fabiani.
(Source: beckman.illinois.edu)
Part of the brain stays “youthful” into older age
At least one part of the human brain may be able to process information the same way in older age as it does in the prime of life, according to new research conducted at the University of Adelaide.
A study compared the ability of 60 older and younger people to respond to visual and non-visual stimuli in order to measure their “spatial attention” skills.
Spatial attention is critical for many aspects of life, from driving, to walking, to picking up and using objects.
"Our studies have found that older and younger adults perform in a similar way on a range of visual and non-visual tasks that measure spatial attention," says Dr Joanna Brooks, who conducted the study as a Visiting Research Fellow with the University of Adelaide’s School of Psychology and the School of Medicine.
"Both younger (aged 18-38 years) and older (55-95 years) adults had the same responses for spatial attention tasks involving touch, sight or sound.
"In one task, participants were asked to feel wooden objects whilst blindfolded and decide where the middle of the object was - participants’ judgements were significantly biased towards the left-hand side of the true object centre. This bias is subtle but highly consistent," Dr Brooks says.
"When we think of ageing, we think not just of the physical aspects but also the cognitive side of it, especially when it comes to issues such as reaction time, which is typically slower among older adults. However, our research suggests that certain types of cognitive systems in the right cerebral hemisphere - like spatial attention - are ‘encapsulated’ and may be protected from ageing," she says.
Dr Brooks, who is now a Research Fellow in Healthy Ageing based at the Australian National University, recently presented her results at the 12th International Cognitive Neuroscience Conference in Brisbane. Her project is part of an international collaboration with scientists at the University of Edinburgh and Queen Margaret University in Scotland to better understand spatial attention in the human brain.
"Our results challenge current models of cognitive ageing because they show that the right side of the brain remains dominant for spatial processing throughout the entire adult lifespan," Dr Brooks says. "We now need to better understand how and why some areas of the brain seem to be more affected by ageing than others."
Dr Brooks’s research could also be helpful in better understanding how diseases such as Alzheimer’s affect the brain.
(Source: adelaide.edu.au)
Older adults have morning brains! Study shows noticeable differences in brain function across the day
Older adults who are tested at their optimal time of day (the morning), not only perform better on demanding cognitive tasks but also activate the same brain networks responsible for paying attention and suppressing distraction as younger adults, according to Canadian researchers.
The study, published online July 7th in the journal Psychology and Aging (ahead of print publication), has yielded some of the strongest evidence yet that there are noticeable differences in brain function across the day for older adults.
“Time of day really does matter when testing older adults. This age group is more focused and better able to ignore distraction in the morning than in the afternoon,” said lead author John Anderson, a PhD candidate with the Rotman Research Institute at Baycrest Health Sciences and University of Toronto, Department of Psychology.
“Their improved cognitive performance in the morning correlated with greater activation of the brain’s attentional control regions – the rostral prefrontal and superior parietal cortex – similar to that of younger adults.”
Asked how his team’s findings may be useful to older adults in their daily activities, Anderson recommended that older adults try to schedule their most mentally-challenging tasks for the morning time. Those tasks could include doing taxes, taking a test (such as a driver’s license renewal), seeing a doctor about a new condition, or cooking an unfamiliar recipe.
In the study, 16 younger adults (aged 19 – 30) and 16 older adults (aged 60-82) participated in a series of memory tests during the afternoon from 1 – 5 p.m. The tests involved studying and recalling a series of picture and word combinations flashed on a computer screen. Irrelevant words linked to certain pictures and irrelevant pictures linked to certain words also flashed on the screen as a distraction. During the testing, participants’ brains were scanned with fMRI which allows researchers to detect with great precision which areas of the brain are activated. Older adults were 10 percent more likely to pay attention to the distracting information than younger adults who were able to successfully focus and block this information. The fMRI data confirmed that older adults showed substantially less engagement of the attentional control areas of the brain compared to younger adults. Indeed, older adults tested in the afternoon were “idling” – showing activations in the default mode (a set of regions that come online primarily when a person is resting or thinking about nothing in particular) indicating that perhaps they were having great difficulty focusing. When a person is fully engaged with focusing, resting state activations are suppressed.
When 18 older adults were morning tested (8:30 a.m. – 10:30 a.m.) they performed noticeably better, according to two separate behavioural measures of inhibitory control. They attended to fewer distracting items than their peers tested at off-peak times of day, closing the age difference gap in performance with younger adults. Importantly, older adults tested in the morning activated the same brain areas young adults did to successfully ignore the distracting information. This suggests that when older adults are tested is important for both how they perform and what brain activity one should expert to see.
“Our research is consistent with previous science reports showing that at a time of day that matches circadian arousal patterns, older adults are able to resist distraction,” said Dr. Lynn Hasher, senior author on the paper and a leading authority in attention and inhibitory functioning in younger and older adults.
The Baycrest findings offer a cautionary flag to those who study cognitive function in older adults. “Since older adults tend to be morning-type people, ignoring time of day when testing them on some tasks may create an inaccurate picture of age differences in brain function,” said Dr. Hasher, senior scientist at Baycrest’s Rotman Research Institute and Professor of Psychology at University of Toronto.
(Source: baycrest.org)
Declining intelligence in old age linked to visual processing
Researchers have uncovered one of the basic processes that may help to explain why some people’s thinking skills decline in old age. Age-related declines in intelligence are strongly related to declines on a very simple task of visual perception speed, the researchers report in the Cell Press journal Current Biology on August 4.
The evidence comes from experiments in which researchers showed 600 healthy older people very brief flashes of one of two shapes on a screen and measured the time it took each of them to reliably tell one from the other. Participants repeated the test at ages 70, 73, and 76. The longitudinal study is among the first to test the hypothesis that the changes they observed in the measure known as “inspection time” might be related to changes in intelligence in old age.
"The results suggest that the brain’s ability to make correct decisions based on brief visual impressions limits the efficiency of more complex mental functions," says Stuart Ritchie of the University of Edinburgh. "As this basic ability declines with age, so too does intelligence. The typical person who has better-preserved complex thinking skills in older age tends to be someone who can accumulate information quickly from a fleeting glance."
Previous studies had shown that smarter people, as measured by standard IQ tests, tend to be better at discerning the difference between two briefly presented shapes, the researchers explain. But before now no one had looked to see how those two measures might change over time as people grow older. The findings were rather unexpected.
"What surprised us was the strength of the relation between the declines," Ritchie says. "Because inspection time and the intelligence tests are so very different from one another, we wouldn’t have expected their declines to be so strongly connected."
The results provide evidence that the slowing of simple, visual decision-making processes might be part of what underlies declines in the complex decision making that we recognize as general intelligence. The results might also find practical use given the simplicity of the inspection time measure, Ritchie says, noting that the test can be taken very simply on a computer and has been used with children, adults, and even patients with dementia or other medical disorders.
"Since the declines are so strongly related, it might be easier under some circumstances to use inspection time to chart a participant’s cognitive decline than it would be to sit them down and give them a full, complicated battery of IQ tests," he says.
(Source: eurekalert.org)
Rigid connections: Molecular basis of age-related memory loss explained
From telephone numbers to foreign vocabulary, our brains hold a seemingly endless supply of information. However, as we are getting older, our ability to learn and remember new things declines. A team of scientists around Associate Prof Dr Antonio Del Sol Mesa from the Luxembourg Centre for Systems Biomedicine of the University of Luxembourg and Dr Ronald van Kesteren of the VU University Amsterdam have identified the molecular mechanisms of this cognitive decline using latest high-throughput proteomics and statistical methods.
The results were published this week in the prestigious scientific journal “Molecular and Cellular Proteomics”.
Brain cells undergo chemical and structural changes, when information is written into our memory or recalled afterwards. Particularly, the number and the strength of connections between nerve cells, the so-called synapses, changes. To investigate why learning becomes more difficult even during healthy ageing, the scientists looked at the molecular composition of brain connections in healthy mice of 20 to 100 weeks of age. This corresponds to a period from puberty until retirement in humans. “Amazingly, there was only one group of four proteins of the so-called extracellular matrix which increased strongly with age. The rest stayed more or less the same,” says Prof Dr Antonio del Sol Mesa from the Luxembourg Centre for Systems Biomedicine.
The extracellular matrix is a mesh right at the connections between brain cells. A healthy amount of these proteins ensures a balance between stability and flexibility of synapses and is vital for learning and memory. “An increase of these proteins with age makes the connections between brain cells more rigid which lowers their ability to adapt to new situations. Learning gets difficult, memory slows down,” Dr Ronald van Kesteren of the VU University Amsterdam elaborates.
In addition, the researchers not only looked at the individual molecules but also analysed the whole picture using a systems biology approach. Here they described the interplay between molecules as networks that together tightly control the amount of individual molecules and their interactions. “A healthy network keeps all molecules in the right level for proper functioning. In older mice we found, however, that the overall molecular composition is more variable compared to younger animals. This shows that the network is losing its control and can be more easily disturbed when we age,” Prof Dr Antonio del Sol Mesa explains. According to the researchers this makes the brain more susceptible to diseases.
Hence, this insight into the normal aging process could also help in the future to better understand complex neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Chemical compounds that modulate the extracellular matrix might be promising new treatments for learning disorders and memory loss.