Prolonged stress destroys memory, new study reveals

According to a new study from researchers at The Ohio State University, long-term stress destroys memory, and the immune system plays a vital role in the cognitive decline.

Long-term stress has been known to cause chronic muscle tension, heart problems, and fertility problems in both men and women. Now, the latest study performed in mice and published in the Journal of Neuroscience suggests chronic stress causes inflammation in the brain, which ultimately leads to memory loss.

The researchers said that the study in mice could one day bring about treatment for repeated, long-term mental attack such as the ones sustained by soldiers, bullying victims, and those who have to deal with beastly bosses. [Read more Small heat shock proteins act as a model for Alzheimer’s treatment]

Lead researcher Jonathan Godbout, Associate Professor of neuroscience at Ohio State said:

"This is chronic stress. It's not just the stress of giving a talk or meeting someone new.”

The first of its kind study was aimed to build the link between short-term memory and prolonged stress. Researchers stressed out several mice by periodically putting a much more aggressive mouse into their cage. [Read more Eating sweet food forms memory of the meal – findings could encourage novel treatment for obesity]

After six days of exposure, the stressed mice could no longer recall the location of a hole to escape a maze, which they remembered easily before the stressful period began.

"The stressed mice didn't recall it. The mice that weren't stressed, they really remembered it," said Godbout.

The stressed-out rodents had changes in their brains, including inflammation brought on by their own immune system. Short-term memory loss was caused by inflammation in the brain, itself the result of the appearance of immune cells called macrophages.

Thus, the researchers pinned the brief memory loss on inflammation, and on the immune system. [Read more How many carbs should you eat if you’re trying to lose weight?]

Godbout said that the effect on memory and evidence that the inflammation in the brain is caused by the immune system are crucial new discoveries.

"It's possible we could identify targets that we can treat pharmacologically or behaviorally," he said.
John Sheridan, co-author and Associate Director of Ohio State's Institute for Behavioral Medicine Research believes it could be that there are ways to interrupt the inflammation.

The mice in the study were exposed to what psychologists call 'repeated social defeat' – in other words they were bullied by a dominant alpha mouse. This was aimed to mimic humans who experience chronic psychosocial stress. [প্রতিদিন কফি পান আপনাকে দীর্ঘদিন বেঁচে থাকতে সাহায্য করবে]

Researchers want to bring to light the secrets behind stress and mood and cognitive problems with a long-term goal of discovering ways to help people who are depressed, anxious and suffer from conditions such as post-traumatic stress disorder (PTSD).

They found that the bullied mice had problem with spatial memory and avoided social contact for up to four weeks, indicating depressive-type behavior.

The stress, it seemed, was causing the mice’s immune systems to attack their own brains, causing inflammation. [প্রতিদিন ফ্রেঞ্চ ফ্রাই খাওয়ার অভ্যাস আপনার মৃত্যু ত্বরান্বিত করতে পারে]

The researchers dosed the mice a drug known to reduce inflammation to see how they would respond. They found that neither the problem in their brain-cell nor the symptoms of depression went away. However, there were no more memory loss and inflammatory macrophages.

The finding led to the conclusion that post-stress memory problem is directly connected to inflammation, and the immune system, rather than brain damage. The impact on memory and confirmation that brain inflammation is caused by the immune system are important new discoveries, said Professor Godbout, and could open new avenues for immune-based treatments. [Read more Changes in brain occur 20 years before Alzheimer’s onset]

Sheridan concluded:

“Stress releases immune cells from the bone marrow and those cells can traffic to brain areas associated with neuronal activation in response to stress.”

“They're being called to the brain, to the center of memory.”

While this isn’t the first time researchers tried to find the link between chronic stress and memory loss, or between inflammation and depression, it gives a new, encouraging connection between all four. The doctors could be benefited by it which may enable them to prescribe more treatments for conditions that are focused on the immune system such as, depression, and anxiety.

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Saliva gland test may provide early detection of Parkinson’s disease

A study by researchers from the Mayo Clinic in Phoenix, Arizona, and Banner Sun Health Research Institute in Sun City, Arizona suggests saliva gland test could become a new way to test for early Parkinson's disease.

Parkinson’s disease is a progressive degenerative disorder of the central nervous system mainly affecting the motor system. It may gradually develop with a barely noticeable tremor in just one hand. But while a tremor may be the most well-known sign of Parkinson's disease, the disorder also commonly causes stiffness or slowing of movement. It also affects sleep, balance, blood pressure and smell.

The motor symptoms of Parkinson's disease result from the death of dopamine-generating cells in the brain. Death of brain cells occur primarily in an area of the brain called the substantia nigra, a region in the midbrain. There is no cure for Parkinson’s, but medications can help control symptoms, often dramatically. In some later cases, surgery may be advised. The disease mostly affects older people, although around 4% of cases are diagnosed before the age of 50 years. Men are in one and a half times higher risk for the disease than women. [Read more Cancer drug may protect against Alzheimer’s, say scientists]

According to Parkinson’s disease Foundation (PDF), a million Americans may be living with the disease, and around 60,000 new cases are diagnosed each year, while thousands remain undetected.

In 2009, an estimated 126,893 cases of Parkinson’s disease were reported in the UK.

Currently there is no test available to diagnose Parkinson’s disease accurately. Doctors usually check medical history, signs and symptoms, perform neurological examination etc. to diagnose the disease.

For the study, the researchers wanted to see if a procedure termed "transcutaneous submandibular gland biopsy" could provide an answer. The procedure extracts a core of gland tissue by inserting a needle into a salivary gland under the jaw. [Read more Top 5 Health Benefits of Omega-3 Fatty Acids]

They were looking for a protein in the cells that could indicate early Parkinson's disease. They took the biopsies from one salivary gland to test for it. In their earlier tests, the same biopsy could detect abnormal protein in 9 out of 12 patients with advanced Parkinson's.

They recruited 25 patients for the new test. These people had the disease for less than 5 years. They also recruited 10 healthy individuals as the control group. [Read more The power of music: It relieves pain during and after surgery]

Of the 25 patients, 19 had sufficient tissue for the study. The researchers tested the biopsied tissues to see if they contained the Parkinson's protein. The results were then compared with those of the healthy control group. [ওজন কমাতে প্রতিদিন আপনার কতটুকু কার্বোহাইড্রেট খাওয়া উচিৎ?]

The protein was found to be present in 14 out of 19 patients.

Study co-author Dr. Thomas Beach, PhD, a neuropathologist with Banner Sun Health Research Institute, said:

"This procedure will provide a much more accurate diagnosis of Parkinson's disease than what is now available. One of the greatest potential impacts of this finding is on clinical trials, as at the present time some patients entered into Parkinson's clinical trials do not necessarily have Parkinson's disease and this is a big impediment to testing new therapies."

Study author Dr. Charles Adler, PhD, neurologist and professor of neurology at the Mayo Clinic, said that using submandibular gland biopsies to test for early Parkinson's disease may help many people because, currently, testing after 10 years gives a far more reliable diagnosis than early testing.

The researchers hope that further studies will increase understanding of the disease and help develop better treatments. [Read more High levels of harmful chemical phthalates detected in people who eat fast food]

The study was published in the journal Movement Disorders.

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Blocking brain inflammation stops Alzheimer’s

Researchers from the University of Southampton have discovered that blocking the production of new immune cells in the brain can help prevent the progression of Alzheimer’s disease. Experts described the findings as “exciting” and said it could lead to new treatments for the disease.

Researchers said their discovery added weight to evidence that inflammation in the brain is what propels the disease. [Read more Drug slows Alzheimer’s by boosting brain’s ‘garbage disposal’ system]

Until now most drugs used to treat dementia have targeted amyloid plaques in the brain which are the hallmarks of Alzheimer's disease.

However, the new study, published in the journal Brain, suggests that progression of the disease could be halted by targeting inflammation in the brain, caused by a build-up of immune cells called microglia.

Alzheimer's is a progressive neurodegenerative disease that slowly destroys memory and cognitive skills, and eventually the ability to carry out the simplest tasks. It is the most common cause of dementia, accounting for about 60-70% of all dementia cases. Together with other forms of dementia, Alzheimer’s affects 47.5 million people worldwide. The disease gives rise to 7.7 million new cases each year.

Alzheimer’s has been recently ranked as the 6^th leading cause of death in the United States. An estimated 5.7 million Americans of all ages have Alzheimer’s, and by 2050 this number is projected to rise to closely 14 million.

Around 800,000 people in the UK are affected by the disease.

Age is one of the risk factors of Alzheimer’s. People over the age of 70 are at a higher risk of developing Alzheimer’s. [স্বল্প শর্করাযুক্ত খাদ্য তালিকায় আপনি কি খেতে পারেন?]

For their study, the researchers compared post-mortem brain tissue samples from healthy people with the brains of people of the same age with Alzheimer's disease. They found increased numbers of microglia in the tissue samples of people with Alzheimer's disease compared with the tissue samples of healthy people. Microglia is a type of cell that, among other things, helps regulate immune responses like inflammation. Previous studies have also suggested that these cells could play an important role.

Next, the scientists wanted to study microglia in mice. They found that mice that were given an oral dose of inhibitor to block a receptor - called CSF1R - responsible for the rise in microglia in their brains, had fewer memory and behavioral problems, compared with untreated mice.

The drug also prevented the loss of communication points between nerve cells in the brain which is commonly seen in people with Alzheimer's. [Read more Research shows narcolepsy medication modafinil will actually make you smart]

The scientists also discovered that the inhibitor did not reduce microglia levels below the number needed for healthy immune function, suggesting blocking CSF1R only eliminates excessive numbers of cells.

However, the treatment did not stop another well-known feature of Alzheimer's disease - build-up of toxic amyloid protein clumps in the animals’ brain.

"These findings are as close to evidence as we can get to show that this particular pathway is active in the development of Alzheimer's disease," said Dr. Diego Gomez-Nicola, lead author and neuroscientist and researcher in biological sciences at Southampton.

Mark Dallas, a neuroscientist at Reading University, said the discovery could explain why drugs designed to treat Alzheimer’s have so far been unsuccessful. [Read more Is ghee healthier than butter?]

“Excitingly, it does however highlight new avenues for researchers to exploit and strengthens the case for targeting other cell types within the brain in the fight against Alzheimer’s,” he added.

For the next step, scientists are planning to build on these findings and work to find a safe drug to test in humans and see if blocking the action of CSF1R has the same effect.

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