Breaking News
May 28, 2018 - Antibody removes Alzheimer’s plaques, in mice
May 28, 2018 - Community paramedicine program for older adults reduced number of 911 calls, improved health
May 28, 2018 - AAP: Congress Urged to Act to Prevent Firearm Deaths
May 28, 2018 - Subjective memory may be marker for cognitive decline
May 28, 2018 - Illinois looks at medical marijuana use for opioid dependence
May 28, 2018 - Specific neurons may cause male aggressiveness
May 28, 2018 - New consensus statement outlines evidence-based medical opinion on abusive head trauma
May 28, 2018 - E-Cigarettes Don’t Help Smokers Quit, But Cash Might
May 28, 2018 - New screening tool developed to assess tanning addiction
May 28, 2018 - Unhappy combination of alcohol, anger, and aggressive behavior
May 28, 2018 - Loyola survey identifies significant group of burn patients with elevated PTSD symptoms
May 28, 2018 - Cancer cells co-opt pain-sensing ‘wasabi receptor’ to survive oxidative stress
May 27, 2018 - New way of grouping atoms could herald novel materials, drugs and computers
May 27, 2018 - Less is more? Gene switch for healthy aging found
May 27, 2018 - Breast cancer survivors do not receive recommended level of screening after surgery
May 27, 2018 - Recommendations Developed for Managing Postpartum Pain
May 27, 2018 - Rheumatoid Arthritis (RA) | Arthritis Basics | Arthritis Types | Arthritis
May 27, 2018 - ‘Life support’ for transplant livers better than freezing: study
May 27, 2018 - Tree nut consumption linked to improved type 2 diabetes health
May 27, 2018 - Income and education gap causes racial differences in health behaviors, study shows
May 27, 2018 - Even at ‘Safe’ Levels, Air Pollution Puts Seniors at Risk
May 27, 2018 - Obstructive sleep apnea linked to thinning of calvaria, skull base
May 27, 2018 - Epigem’s Managing Director sets the bar for life sciences industry at VentureFest
May 27, 2018 - CPAP may reduce resting heart rate in prediabetic patients
May 27, 2018 - Study reveals striking disparities in health care access and quality across most nations
May 27, 2018 - The Yogi masters were right—meditation and breathing exercises can sharpen your mind
May 27, 2018 - SLU researcher aims to find solutions for diabetes patients at risk of hypoglycemia
May 27, 2018 - Scientists uncover the cause of insulin resistance in obesity
May 27, 2018 - $2.3 million NIH grant to support new project on oxytocin neurons and social behavior
May 27, 2018 - Less Driving Tied to Lower Cardiovascular Disease Risk
May 27, 2018 - Genetics Home Reference: LMNA-related congenital muscular dystrophy
May 27, 2018 - Long-term psychological study confirms time is the best medicine against homesickness
May 27, 2018 - Study explores if CPAP treatment can improve sexual QOL for sleep apnea patients
May 27, 2018 - Study investigates role played by brain in prosocial behavior
May 27, 2018 - New Guidelines Mean 1 in 3 Adults May Need Blood Pressure Meds
May 27, 2018 - Cerebrospinal Fluid (CSF) Analysis: MedlinePlus Lab Test Information
May 27, 2018 - Kids in tough neighborhoods head to ER more often
May 27, 2018 - Exercise alters brain’s dopamine system to help treat addiction, study finds
May 27, 2018 - Sepsis patients treated and released from ED for outpatient follow-up experience good outcomes
May 27, 2018 - Initiative cuts overuse of tests, treatments for bronchiolitis
May 27, 2018 - Study links ‘sleep spindles’ to memory reactivation
May 27, 2018 - Scientists develop new method to speed up genome evolution of baker’s yeast
May 27, 2018 - Sunscreen pills are fake says FDA
May 27, 2018 - Study finds increasing wealth gap between households of seniors and families with children
May 27, 2018 - Link between tuberculosis and Parkinson’s disease discovered
May 27, 2018 - Doctors call on health authorities for permission to provide stroke patients with life-saving treatment
May 26, 2018 - Couples who eat seafood-rich diet tend to get pregnant faster
May 26, 2018 - NIH summit presents recommendations to accelerate treatment development for Alzheimer’s disease
May 26, 2018 - Medication-related harm found to be common among older adults, but preventable
May 26, 2018 - Lunaphore and Vitro announce partnership to develop ISH protocols for RNA, DNA targets
May 26, 2018 - Cryoablation Efficacious for Cancer Pain, Review Finds
May 26, 2018 - Link between IBD and Parkinson’s might allow doctors to slow down condition
May 26, 2018 - Study finds fewer than 5% of low-income, urban mothers use prenatal vitamins before pregnancy
May 26, 2018 - California hospitals urge moms to favor breast milk over formula
May 26, 2018 - Most concussion patients do not receive follow-up care after hospital discharge, says study
May 26, 2018 - Lifetime risks of developing Alzheimer’s dementia vary by age, gender
May 26, 2018 - Researchers find novel ways to improve participation in clinical research
May 26, 2018 - Researchers develop methods for measuring free-base nicotine levels in e-cigarettes
May 26, 2018 - AHA: Preterm Birth Could Warn of Mom’s Future Heart Risks
May 26, 2018 - Some calories more harmful than others
May 26, 2018 - Study links cell size with commitment to division
May 26, 2018 - Researchers develop new, rapid blood test to detect liver damage
May 26, 2018 - Researchers discover cascade of immune processes linked to poor outcomes in aggressive breast cancer
May 26, 2018 - New research will use mathematics to solve mysteries in cell biology
May 26, 2018 - Proposed National Resilience Strategy to reverse catastrophic increases in ‘deaths of despair’
May 26, 2018 - Mice remain slim on burger diet
May 26, 2018 - BMC receives $13.5 million award to test methods for delivering childhood anxiety treatment
May 26, 2018 - ‘Right to Try Act’ will not benefit terminally-ill patients
May 26, 2018 - Study reveals novel statistical algorithm to identify potential disease genes
May 26, 2018 - Two genes play vital roles in malignant brain cancer
May 26, 2018 - Study explores link between groundwater lithium and diagnoses of bipolar disorder, dementia
May 26, 2018 - Researchers reveal stimulatory effects of myelin on young neural cells
May 26, 2018 - Small part of cellular protein that helps form long-term memories also drives neurodegeneration
May 26, 2018 - Four-legged friends can have heart issues, too
May 26, 2018 - Scientists create small, self-contained spaces inside mammalian cells
May 26, 2018 - Better Social Support Network Protects Black Men Against HIV
May 26, 2018 - National Heart, Lung, and Blood Institute (NHLBI)
May 26, 2018 - Burnout, depression can affect ophthalmology residents, study finds
May 26, 2018 - Latinos and African Americans more likely to experience serious depression than Whites
May 26, 2018 - Data from past epidemic could help improve response to future Ebola outbreaks
Is Alzheimer’s caused by disruptions to the brain’s energy supply?

Is Alzheimer’s caused by disruptions to the brain’s energy supply?

image_pdfDownload PDFimage_print
Credit: Raytron/Shutterstock.com

It is well known that Alzheimer’s disease, the most common form of dementia, involves the accumulation of sticky proteins (plaques and tangles) in the brain. But we still don’t know what the root cause of the disease is. Given that someone, somewhere in the world, is diagnosed with dementia every three seconds, there is an urgent race to discover the causes of the disease so that treatments can be developed.

Scientists know that changes to the brain’s blood flow happen before plaques and tangles appear and this has led to an interesting theory of the causes of the disease, known as the vascular hypothesis.

When brain cells become active, they need energy in the form of glucose and oxygen, which is delivered by an increase in blood supply to that part of the brain. But in Alzheimer’s disease the blood supply is often impaired, so the amount of energy supplied to the brain cells is compromised. One of the reasons for the breakdown in this energy supply may be explained by a breakdown in the blood-brain barrier.

Capillaries in the brain are lined with very tightly packed endothelial cells that form a semi-permeable barrier. They let oxygen, glucose and other necessary substances across the barrier, but stop larger molecules from crossing into the brain. Research has shown that in people with Alzheimer’s, the integrity of this barrier is compromised due to gaps forming in the usually tightly packed endothelial cells. This leads to a build-up of harmful molecules in the brain, which in turn results in swelling of the brain and reduced blood flow in it.

A lack of oxygen to the brain (a condition known as “hypoxia”) has been shown to lessen the ability of neurons to fire and to alter brain chemistry. This causes brain swelling, lesions and, importantly, helps the formation of beta-amyloid plaques and tau tangles – the hallmark features of Alzheimer’s. So the degeneration of these blood vessels in the brain may form a vicious cycle, eventually resulting in mass cell death.

The role of the APOE gene

Another hint that Alzheimer’s disease may be caused by poor blood flow to the brain comes from genetics.

Plaques (in yellow) clumping on a neuron. Credit: Juan Gaertner/Shutterstock.com

The gene associated with the highest risk of developing Alzheimer’s disease later in life is called APOE. Everyone inherits two copies of this gene, one from each parent, and APOE exists in three variants (alleles), called e2, e3 and e4. People with two copies of the e4 variant of the gene (“APOE4”) increase their risk of developing Alzheimer’s disease by about three to five times.

Researchers from John Hopkins University showed that people with the APOE4 gene had reduced brain blood flow, without any symptoms of Alzheimer’s disease. And a separate study, using genetically engineered mice with the human APOE genes, showed that APOE4 resulted in damage to the capillaries before any decline in brain-cell activity became evident. These findings support the idea that blood flow disruptions may be one of the earliest changes in Alzheimer’s disease.

A vascular theory of Alzheimer’s disease may also explain why people who have high blood pressure, or who have had a stroke, are more likely to develop the disease. High blood pressure can cause blood clots to form in the arteries leading to your brain, which reduces blood flow and oxygenation.

A stroke may occur as a result of such blood clots, meaning the blood supply to a part of the brain is suddenly cut off. Both of these conditions decrease the energy supply to the brain, which can damage brain cells significantly.

We need a different target

There are no cures for Alzheimer’s disease, only drugs to manage some of the symptoms. The new treatments that are being investigated tend to focus on removing plaques, which may or may not recover function. But perhaps a better target for drug developers would be medicines that treat changes to the blood vessels, before brain cells are affected.

In a 2012 study, published in Nature, researchers at the University of Rochester gave an immunosuppressant drug called cyclosporine to mice with the human APOE4 gene. They showed that, following this treatment, the early damage to capillaries and the blood-brain barrier were recovered. Clearly, genetically modified mice are not the same as humans, but the findings do lend further support to the vascular hypothesis.

And more than just shedding light on new drug treatment options, the vascular hypothesis also emphasises the importance of maintaining good cardiovascular health. Physical activity increases your heart rate and the blood flow to the brain, which increases oxygenation and improves the general health of your brain cells. As the saying goes, an ounce of prevention is worth a pound of cure.


Explore further:
Antibody removes Alzheimer’s plaques, in mice

Journal reference:
Nature

Provided by:
The Conversation

Tagged with:

About author

Related Articles