Tag Archives: brain function

Sleep apnea, lack of deep sleep linked to worse brain health

People who have sleep apnea and spend less time in deep sleep may be more likely to have brain biomarkers that have been linked to an increased risk of stroke, Alzheimer’s disease and cognitive decline, according to new research published in the May 10, 2023, online issue of Neurology®, the medical journal of the American Academy of Neurology. The study does not prove that these sleep disturbances cause the changes in the brain, or vice versa. It only shows an association.

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The study looked at sleep factors and biomarkers of the health of the brain’s white matter. The biomarkers measure how well the brain’s white matter is preserved, which is important to connect different parts of the brain. One of the biomarkers, white matter hyperintensities, are tiny lesions visible on brain scans. White matter hyperintensities become more common with age or with uncontrolled high blood pressure. The other biomarker measures the integrity of the axons, which form the nerve fibers that connect nerve cells.

“These biomarkers are sensitive signs of early cerebrovascular disease,” said study author Diego Z. Carvalho, MD, MS, of the Mayo Clinic in Rochester, Minnesota, and a member of the American Academy of Neurology. “Finding that severe sleep apnea and a reduction in slow-wave sleep are associated with these biomarkers is important since there is no treatment for these changes in the brain, so we need to find ways to prevent them from happening or getting worse.”

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Fresh understanding of aging in the brain offers hope for treating neurological diseases

Scientists from the Trinity Biomedical Sciences Institute (TBSI) have shed new light on aging processes in the brain. By linking the increased presence of specialized immune cells to conditions such as Alzheimer’s disease and traumatic brain injury for the first time, they have unearthed a possible new target for therapies aimed at treating age-related neurological diseases.

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The research, which benefited from a collaboration with experts at the University of Maryland School of Medicine and focused on microglia in the brain and spinal cord, is published in leading international journal, Science Advances.

Microglia are a unique type of immune cell whose job it is to support nerve cells, defend against invading microbes, clear debris and remove dying nerve cells by engulfing and eating them. Emerging research indicates that microglia can have different functional responses depending on molecular and biochemical changes occurring within these specialized cells. 

In fact, various subtypes of microglia can be distinguished based on a property called autofluorescence. This is the tendency of cells to emit light of one color after they have absorbed light of another, and it occurs because specific substances inside the cells absorb light. The substances stored in specialized cellular compartments include fat molecules, cholesterol crystals, metals and other misfolded proteins. 

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Alcohol Consumption May be Linked to Acceleration of Alzheimer’s Disease

Alzheimer’s disease is the most common form of dementia, accounting for 60% to 80% of dementia cases, according to the Alzheimer’s Association. While current research suggests alcohol use disorder is a risk factor in Alzheimer’s disease, the impact alcohol use disorder has on Alzheimer’s disease pathology is an area of continued research.

In a new preclinical study, scientists at Wake Forest University School of Medicine showed that even modest amounts of alcohol can accelerate brain atrophy, which is the loss of brain cells, and increase the number of amyloid plaques, which are the accumulation of toxic proteins in Alzheimer’s disease.

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The study appears in the February issue of Neurobiology of Disease.

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The ‘tipping point’ toward Alzheimer’s

New electrical method triggers and analyzes dynamics of brain protein that underlie many neurodegenerative diseases

Scientists are not yet clear on how the tau protein changes from a benign protein essential for normal function in our brains into the toxic neurofibrillary tangles that are a signature of Alzheimer’s and other neurodegenerative diseases.

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But a new method developed by researchers at UC Santa Barbara gives the ability to control and follow in real time the process by which it happens. The technique employs a novel use of low voltage electricity as a surrogate for the natural signals that trigger the protein to fold and assemble, both for its normal function in the brain and in the runaway process leading to often fatal disease.

“This method provides scientists a new means to trigger and simultaneously observe the dynamic changes in the protein as it transitions from good to bad,” said Daniel E. Morse,  Distinguished Professor Emeritus of Biochemistry and Molecular Genetics, and senior author of a paper that appears in the Journal of Biological Chemistry.

“The method should be widely useful to identify molecules and conditions that direct different trajectories of assembly in a number of different but related amyloid diseases,” stated Eloise Masqulier, lead author of the interdisciplinary team of students, researchers and faculty from molecular biology, chemistry and engineering including Esther Taxon, Sheng-Ping Liang, Yahya Al Sabeh, Lior Sepunaru and Michael J. Gordon.

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Three or more concussions linked with worse brain function in later life …

Experiencing three or more concussions is linked with worsened brain function in later life, according to major new research.

The study – the largest of its kind – also found having just one moderate-to-severe concussion, or traumatic brain injury (TBI), can have a long-term impact on brain function, including memory.

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Led by teams at the University of Oxford and the University of Exeter, the research included data from more than 15,000 participants of the online PROTECT study, who were aged between 50 and 90 and based in the UK. They reported the severity and frequency of concussions they had experienced throughout their lives, and completed annual, computerized tests for brain function.

Published in the Journal of Neurotrauma, the paper found that people who reported three or more concussions had significantly worse cognitive function, which got successively worse with each subsequent concussion after that. Attention and completion of complex tasks were particularly affected.

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New test could detect Alzheimer’s disease 3.5 years before clinical diagnosis

New research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London has established a blood-based test that could be used to predict the risk of Alzheimer’s disease up to 3.5 years before clinical diagnosis.

The study, published in the journal Brain, supports the idea that components in the human blood can modulate the formation of new brain cells, a process termed neurogenesis. Neurogenesis occurs in an important part of the brain called the hippocampus that is involved in learning and memory.

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While Alzheimer’s disease affects the formation of new brain cells in the hippocampus during the early stages of the disease, previous studies have only been able to study neurogenesis in its later stages through autopsies.

To understand the early changes, researchers collected blood samples over several years from 56 individuals with Mild Cognitive Impairment (MCI), a condition where someone will begin to experience a worsening of their memory or cognitive ability. While not everyone experiencing MCI goes on to develop Alzheimer’s disease, those with the condition progress to a diagnosis at a much higher rate than the wider population. Of the 56 participants in the study, 36 went on to receive a diagnosis of Alzheimer’s disease.

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Gut bacteria affect brain health- Study

A growing pile of evidence indicates that the tens of trillions of microbes that normally live in our intestines — the so-called gut microbiome — have far-reaching effects on how our bodies function. Members of this microbial community produce vitamins, help us digest food, prevent the overgrowth of harmful bacteria and regulate the immune system, among other benefits. Now, a new study suggests that the gut microbiome also plays a key role in the health of our brains, according to researchers from Washington University School of Medicine in St. Louis.

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The study, in mice, found that gut bacteria — partly by producing compounds such as short chain fatty acids — affect the behavior of immune cells throughout the body, including ones in the brain that can damage brain tissue and exacerbate neurodegeneration in conditions such as Alzheimer’s disease. The findings, published Jan. 13 in the journal Science, open up the possibility of reshaping the gut microbiome as a way to prevent or treat neurodegeneration.

“We gave young mice antibiotics for just a week, and we saw a permanent change in their gut microbiomes, their immune responses, and how much neurodegeneration related to a protein called tau they experienced with age,” said senior author David M. Holtzman, MD, the Barbara Burton and Reuben M. Morriss III Distinguished Professor of Neurology. “What’s exciting is that manipulating the gut microbiome could be a way to have an effect on the brain without putting anything directly into the brain.”

Evidence is accumulating that the gut microbiomes in people with Alzheimer’s disease can differ from those of healthy people. But it isn’t clear whether these differences are the cause or the result of the disease — or both — and what effect altering the microbiome might have on the course of the disease.

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Hearing loss linked with dementia in older adults – Study

A new study led by researchers at the Johns Hopkins Bloomberg School of Public Health found that older adults with greater severity of hearing loss were more likely to have dementia, but the likelihood of dementia was lower among hearing aid users compared to non-users.

The findings, from a nationally representative sample of more than 2,400 older adults, are consistent with prior studies showing that hearing loss might be a contributing factor to dementia risk over time, and that treating hearing loss may lower dementia risk.

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The findings are highlighted in a research letter published online January 10 in the Journal of the American Medical Association.

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Researchers reveal how trauma changes the brain

Exposure to trauma can be life-changing – and researchers are learning more about how traumatic events may physically change our brains. But these changes are not happening because of physical injury, rather our brain appears to rewire itself after these experiences. Understanding the mechanisms involved in these changes and how the brain learns about an environment and predicts threats and safety is a focus of the ZVR Lab at the Del Monte Institute for Neuroscience at the University of Rochester, which is led by assistant professor Benjamin Suarez- Jimenez, Ph.D.

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“We are learning more about how people exposed to trauma learn to distinguish between what is safe and what is not. Their brain is giving us insight into what might be going awry in specific mechanisms that are impacted by trauma exposure, especially when emotion is involved,” said Suarez-Jimenez, who began this work as a post-doctoral fellow in the lab of Yuval Neria, Ph.D., professor at Columbia University Irving Medical Center.

Their research, recently published in Communications Biology, identified changes in the salience network – a mechanism in the brain used for learning and survival – in people exposed to trauma (with and without psychopathologies, including PTSD, depression, and anxiety). Using fMRI, the researchers recorded activity in the brains of participants as they looked at different-sized circles – only one size was associated with a small shock (or threat). Along with the changes in the salience network, researchers found another difference – this one within the trauma-exposed resilient group. They found the brains of people exposed to trauma without psychopathologies were compensating for changes in their brain processes by engaging the executive control network – one of the dominate networks of the brain.

“Knowing what to look for in the brain when someone is exposed to trauma could significantly advance treatments,” said Suarez-Jimenez, a co-first author with Xi Zhu, PhD, Assistant Professor of Clinical Neurobiology at Columbia, of this paper. “In this case, we know where a change is happening in the brain and how some people can work around that change. It is a marker of resilience.”

Adding the element of emotion

The possibility of threat can change how someone exposed to trauma reacts – researchers found this is the case in people with post-traumatic stress disorder (PTSD), as described in a recent study in Depression & Anxiety. Suarez-Jimenez, his fellow co-authors, and senior author Neria found patients with PTSD can complete the same task as someone without exposure to trauma when no emotion is involved. However, when emotion invoked by a threat was added to a similar task, those with PTSD had more difficulty distinguishing between the differences.

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Brain Benefits of Exercise

I think of this as a variation on one-picture-is-worth-1000 words.

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Omega-3s linked to improved midlife brain structure, cognition

Holy mackerel! Could eating salmon, cod, tuna, herring or sardines keep our brains healthy and our thinking agile in middle age? New research makes this connection.

Eating cold-water fish and other sources of omega-3 fatty acids may preserve brain health and enhance cognition in middle age, new evidence indicates.

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Having at least some omega-3s in red blood cells was associated with better brain structure and cognitive function among healthy study volunteers in their 40s and 50s, according to research published online Oct. 5 in Neurology®, the medical journal of the American Academy of Neurology. Faculty of The University of Texas Health Science Center at San Antonio (UT Health San Antonio) and other investigators of the Framingham Heart Study conducted the analysis.

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Decreased proteins, not amyloid plaques, tied to Alzheimer’s disease – Study

New research from the University of Cincinnati bolsters a hypothesis that Alzheimer’s disease is caused by a decline in levels of a specific protein, contrary to a prevailing theory that has been recently called into question.

UC researchers led by Alberto Espay, MD, and Andrea Sturchio, MD, in collaboration with the Karolinska Institute in Sweden, published the research on Oct. 4 in the Journal of Alzheimer’s Disease.

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Questioning the dominant hypothesis

The research is focused on a protein called amyloid-beta. The protein normally carries out its functions in the brain in a form that is soluble, meaning dissolvable in water, but it sometimes hardens into clumps, known as amyloid plaques.

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SuperAger brains contain ‘super neurons’ – NW

·  SuperAger neurons are even larger than those in individuals 20 to 30 years younger
·  These neurons do not have tau tangles that are a hallmark of Alzheimer’s
·  Larger neurons in the brain’s memory region are a biological signature of SuperAging trajectory

Neurons in an area of the brain responsible for memory (known as the entorhinal cortex) were significantly larger in SuperAgers compared to cognitively average peers, individuals with early-stage Alzheimer’s disease and even individuals 20 to 30 years younger than SuperAgers — who are aged 80 years and older, reports a new Northwestern Medicine study.

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These neurons did not harbor tau tangles, a signature hallmark of Alzheimer’s disease.

“The remarkable observation that SuperAgers showed larger neurons than their younger peers may imply that large cells were present from birth and are maintained structurally throughout their lives,” said lead author Tamar Gefen, an assistant professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. “We conclude that larger neurons are a biological signature of the SuperAging trajectory.”  

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Machine learning gives glimpse of how a dog’s brain represents what it sees

Okay, this doesn’t have any obvious connection to living a long and healthy life, but I am a dog-lover and believe that there are more connections between our two species than meets the eye.

Scientists have decoded visual images from a dog’s brain, offering a first look at how the canine mind reconstructs what it sees. The Journal of Visualized Experiments published the research done at Emory University. 

Credit: Emory Canine Cognitive Neuroscience Lab

The results suggest that dogs are more attuned to actions in their environment rather than to who or what is doing the action.

The researchers recorded the fMRI neural data for two awake, unrestrained dogs as they watched videos in three 30-minute sessions, for a total of 90 minutes. They then used a machine-learning algorithm to analyze the patterns in the neural data.

“We showed that we can monitor the activity in a dog’s brain while it is watching a video and, to at least a limited degree, reconstruct what it is looking at,” says Gregory Berns, Emory professor of psychology and corresponding author of the paper. “The fact that we are able to do that is remarkable.”

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A brain mechanism underlying the evolution of anxiety

Monoamine neurotransmitters such as serotonin and dopamine play important roles in our cognitive and emotional functions. Their evolutionary origins date back to metazoans, and while the function of related genes is strongly evolutionarily conserved, genetic variation within and between species has been reported to have a significant impact on animal mental characteristics such as sociality, aggression, anxiety, and depression.

A research group led by Dr Daiki Sato and Professor Masakado Kawata has previously reported that the vesicular monoamine transporter 1 (VMAT1) gene, which transports neurotransmitters to secretory vesicles in neurons and secretory cells, has evolved through natural selection during human evolution. In particular, the 136th amino acid locus of this gene has evolved in the human lineage from asparagine (Asn) to threonine (Thr), and moreover, a new allele (isoleucine, Ile) has emerged and increased in its frequencies around the world. Previous reports suggested that people with the Ile genotype are less prone to depression and anxiety than those with the Thr genotype, but it was unclear how these human-specific mutations function in the brain and lead to changes in neuropsychiatric behavior.

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Social isolation impacts brain function in significant ways

Social isolation rewires the brain in myriad ways, potentially leading to anxiety, depression, addiction, and other behavioral changes. The findings were presented at Neuroscience 2021, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health. 

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Humans are a highly social species who crave social contact for their well-being. Loneliness induced by social isolation can cause significant neurological and behavioral changes that may lead to health issues. Given the widespread experience of loneliness during the COVID-19 pandemic, there is a need to better understand and prevent the long-term effects of social isolation. Scientists are just beginning to understand these changes and hope to find ways to curb their negative effects. 

Today’s new findings show:

  • Young mice exposed to chronic social isolation demonstrated a long-term deficit in social recognition and an altered circuit between the prefrontal cortex and nucleus accumbens (Yong-Seok Lee, Seoul National University College of Medicine).
  • Social isolation in adolescent mice led to increased cocaine use and relapse rates, as well as sex-dependent structural changes in the prefrontal cortex and nucleus accumbens (Lisa A. Briand, Temple University).
  • Social isolation in young rats led to an increase in weight, anxiety, and dopamine release in the nucleus accumbens, but exercise mitigated anxiety and weight gain (Enrique U. Pérez-Cardona, University of Puerto Rico at Carolina).
  • Lower social rank in mice is predictive of greater alcohol intake, but social isolation increases intake for all mice — regardless of rank — and increases the excitability of the basolateral amygdala (Reesha R. Patel, Salk Institute for Biological Studies).
  • A socially monogamous prairie vole model mimicked human responses after the loss of a partner; these behavioral changes may be linked to disturbances in the brain’s oxytocin system (Adam S. Smith, University of Kansas).

“This research shows that social isolation impacts many brain regions and affects many different behaviors, resulting in increased risk for disease,” said Alexa H. Veenema, the director of the Neurobiology of Social Behavior Laboratory and an associate professor at Michigan State University. “The pandemic has had a tremendous effect on our mental health. This research will provide us with insights about which specific neural circuits mediate the behavioral effects induced by social isolation. We can then find ways to restore these neural circuits, counteracting the consequences of social isolation”

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