Scientists have discovered that a protein that controls weight and appetite may also help prevent Alzheimer’s disease (AD).

Patients with higher leptin levels had a significantly lower risk of developing the debilitating disorder, according to a study found in the Journal of the American Medical Association.

Researchers from the Boston University School of Medicine indicated that there is growing evidence to suggest that leptin has beneficial effects on brain development and function, which is what inspired them to conduct their own study.

The scientists measured participants’ leptin levels over a 12-year period. They discovered that patients with higher levels of the protein had a significantly lower risk of developing the brain disease.

“Over a 12-year follow-up, this corresponds to an absolute AD risk of 25 percent for persons with the lowest levels of leptin compared to a six percent risk for persons with the highest levels,” said senior author Dr. Sudha Seshadri.

Some health officials recommend taking nutritional supplements such as fish oils or antioxidants to improve cell membranes that may curb Alzheimer’s symptoms.

Experiments on mice may help scientists understand the workings of the prion protein linked to brain disease vCJD.

Swiss researchers say there is evidence that prions play a vital role in the maintenance of the sheath surrounding our nerves.

They say it is possible that an absence of prions causes diseases of the peripheral nervous system.

One expert said there was growing evidence that the prion had a number of important roles in the body.

As well as the latest research in the journal Nature Neuroscience, other studies have indicated prions may protect us from Alzheimer’s disease or even play a role in our sense of smell.

The prion protein only came to the attention of scientists in recent years as they searched for the cause of vCJD – the human variant of BSE, or Mad Cow Disease.

This degenerative and incurable brain condition is now thought to be caused by a “mis-folded” version of the prion.

However, there is still little understanding of what the protein is supposed to do in its normal, healthy, form.

Healthy prions

The study, by scientists at the University Hospital in Zurich, looked at mice bred with fewer prion proteins.

While these mice are known to be resistant to prion diseases equivalent to vCJD in humans, they showed a number of abnormalities, including a degeneration, later in life, of the peripheral nerve cells, and the protective myelin sheath which surrounds them.

Peripheral nerves are those which link the limbs and organs to the central nervous system – the spinal cord and brain.

Looking more closely, researchers examined the effects of removing the prion protein in both the nerve cells themselves, and the Schwann cells surrounding them, which are responsible for making the myelin sheath.

While removing protein from the Schwann cells had no effect, taking it from the neurons led to a breakdown of the myelin and degeneration of the nerve cells.

They said that the knowledge that prion protein played some role in the healthy upkeep of nerve cells could offer a new avenue of research into diseases affecting humans.

However, scientists caution that it is too early to pick out a particular peripheral nerve condition which might correspond to the mouse experiments.

Recent work

Professor Nigel Hooper, from the University of Leeds, agreed that the role of the protein was not well understood.

His own work, published in 2007, suggested that it might offer some protection from the development of Alzheimer’s disease.

But he said this was unlikely to be the complete answer.

He said: “Most people started by focusing on prions in relation to a human disease, and have only recently started to examine what it normally does.

“There is some evidence that it could have a number of different roles, depending on its whereabouts in the body – a recent paper linked it to olfaction or the sense of smell.”

An ingredient found in the natural supplement green tea may help treat brain diseases such as Alzheimer’s, Huntington’s and Parkinson’s.

According to a study published in Natural Chemical Biology, mixing EGCG, a green tea ingredient, with the chemical DAPH-12 may help destroy amyloids—proteins that can lead to brain diseases.

Some feel this study is significant as no other research has found a chemical combination to destroy amyloids. Researchers found that while EGCG could destroy weaker amyloids on its own, it needed to be mixed with DAPH-12 to destroy the stronger proteins.

While the researchers said they were excited with the outcome of finding a potential way to treat the diseases, they are quick to point out there is still more research to be done to see if they could find other possible solutions.

“Our findings are certainly preliminary and we need further work to fully comprehend the effects of EGCG in combination with other chemicals on amyloids,” said co-author Dr. Martin Duennwald. “Yet, we see our study as a very exciting initial step toward combinatorial therapies for the treatment of amyloid-based diseases.”

US scientists believe they have uncovered one of the mechanisms that enables the brain to form memories.

Synapses – where brain cells connect with each other – have long been known to be the key site of information exchange and storage in the brain.

But researchers say they have now learnt how molecules at the site of the synapse behave to cement a memory.

It is hoped the research, published in Neuron, could aid the development of drugs for diseases like Alzheimer’s.

The deteriorating health of the synapses is increasingly thought to be a feature of Alzheimer’s, a disease in which short-term memory suffers before long-term recollections are affected.

A strong synapse is needed for cementing a memory, and this process involves making new proteins. But how exactly the body controls this process has not been clear.

Now scientists at the University of California Santa Barbara say their laboratory work on rats shows the production of proteins needed to cement memories can only happen when the RNA – the collection of molecules that take genetic messages from the nucleus to the rest of the cell – is switched on.

Until it is required, the RNA is paralysed by a “silencing” molecule – which itself contains proteins.

When an external signal comes in – for example when one sees something interesting or has an unusual experience – the silencing molecule fragments and the RNA is released.

Kenneth Kosik of the university’s neuroscience research institute said: “One reason why this is interesting is that scientists have been perplexed for some time as to why, when synapses are strengthened, you have the degradation of proteins going on side by side with the synthesis of new proteins.

“So we have now resolved this paradox. We show that protein degradation and synthesis go hand in hand. The degradation permits the synthesis.”

Identifying the proteins the brain needs in order to cement the memory could ultimately have benefits for those suffering from memory disorders.

Rebecca Wood, head of the Alzheimer’s Research Trust, said: “Scientists say they have studied nerve cells in the laboratory and learnt more about how specific proteins may have a role in areas of the brain that transmit messages and help us store memories.

“This interesting development could give a greater understanding of the memory loss experienced by people with Alzheimer’s and other forms of dementia and lead to new treatments.”

The most recent projections suggest 115 million people across the globe will suffer from dementia by 2050.

Julie Williams, professor of psychological medicine at Cardiff University, said: “Our increasing understanding of genetic risk factors in Alzheimer’s is pointing to the synapses so any new study in this area is welcome.

“Alzheimer’s is a complicated disease and it is early days, but the health of synapses and their activity levels is becoming an important and interesting focus of research.”

According to a study published in Natural Chemical Biology, when EGCG, a green tea ingredient mixed with chemical DAPH-12, it may help destroy amyloids, which are proteins that bring on the brain diseases.

Some feel this study is significant as no other research has found a chemical combination to destroy amyloids. Researchers found that while EGCG could destroy weaker amyloids on their own, it needed to be mixed with DAPH-12 to destroy the stronger proteins.

While the researchers said they were excited with the outcome of finding a potential way to treat the diseases, they are quick to point out there is still more research to be done to see if they could find other possible solutions.

“Our findings are certainly preliminary and we need further work to fully comprehend the effects of EGCG in combination with other chemicals on amyloids,” said co-author Dr. Martin Duennwald. “Yet, we see our study as a very exciting initial step towards combinatorial therapies for the treatment of amyloid-based diseases.”

While homocysteine is needed for the metabolism, too much of it can lead to a higher risk of heart disease, stroke and peripheral vascular disease.

Previous studies have looked at the link between homocysteine levels and dementia but have only had a follow-up of eight years. The newest study has a 35-year follow-up that may offer more definitive answers.

“Alzheimer’s disease was more than twice as common among the women with the highest levels of homocysteine than among those with the lowest, and the risk for any kind of dementia was 70 percent higher,” said study author Dr. Dimitri Zylberstein.

Originally, it was believed that homocysteine levels were affected by vitamin deficiency, leading some to turn to nutritional supplements in order to get their levels on track. It has since been discovered that even individuals with normal vitamin levels may still have high amounts of homocysteine, negating the previous theory.

A study in the Journal of Agricultural and Food Chemistry is looking into nano-sized capsule made with curcumin, an ingredient that makes curry yellow, that could potentially help in fighting colon cancer, psoriasis and Alzheimer’s disease.

It’s been found that curcumin prevents melanoma cell growth by forcing the cells to destroy themselves. In addition to this, curcumin also works as a nutritional supplement for antioxidant effects.

One problem the researchers are facing is that the digestive system quickly destroys curcumin, making it nearly impossible to reach the bloodstream.

The scientists are working to find a way for curcumin to get past the digestive system by incorporating insulin and other drugs that can help with absorption.

The ultimate goal of this study is to find a potential in this natural ingredient that may help prevent some of the most common killers in humans today.

Assistant Professor Hiro Furukawa, Ph.D., and colleagues at CSHL, in cooperation with the National Synchrotron Light Source at Brookhaven National Laboratory, obtained crystal structures for one of several “subunits” of the NMDA receptor. This receptor, formally called the N-methyl-D-aspartate receptor, belongs to a family of cellular receptors that mediate excitatory nerve transmission in the brain. Excitatory signals represent the majority of nerve signals in most regions of the human brain.

One theory of causation in Alzheimer’s, Parkinson’s and multiple sclerosis posits that excessive amounts of the excitatory neurotransmitter, glutamate, can cause an overstimulation of glutamate receptors, including the NMDA receptor. Such excitotoxicity, the theory holds, can cause nerve-cell death and subsequent neurological dysfunction. A class of inhibitors of the NMDA receptor under the generic name Memantine has been approved by the U.S. Food and Drug Administration for use in moderate and severe cases of Alzheimer’s.

Memantine is a non-specific inhibitor of the NMDA receptor and is neither a cure nor an agent that can halt progression of the disease. The search is well under way for molecules that can shut down the NMDA receptor with much greater specificity. The CSHL team’s work pertains directly to that effort. The NMDA receptor is modular, composed of multiple domains with distinct functional roles. Part of the receptor is lodged in the membrane of nerve cells and part juts out from the membrane. Furukawa’s CSHL team focused on a portion of the so-called extracellular domain of the receptor, a subunit called NR2B, which includes a domain of particular interest called the ATD (the amino terminal domain).

“This part is of great interest to us because it has very little in common with ATDs in other kinds of glutamate receptors involved in nerve transmission,” says Furukawa. Its uniqueness makes it a potentially interesting target for future drugs. “Our interest is even keener because we already know there are a rich spectrum of small molecules that can bind the ATD of NMDA receptors.” Without a highly detailed molecular picture of the ATD, however, efforts to rationally design inhibitors cannot proceed.

Hence the importance of Furukawa’s achievement: a crystal structure revealed by the powerful light source at Brookhaven National Laboratory, that shows the ATD to have a “clamshell”-like appearance that is important for its function. The results are published in a paper appearing online Thursday ahead of print in The EMBO Journal, the publication of the European Molecular Biology Organization. The team obtained structures of the ATD domain with and without zinc binding to it.

Zinc is a natural ligand that docks at a spot within the “clamshell” in routine functioning of the NMDA receptor. Of much greater interest is the location and nature of a suspected binding site of a small molecule type that is known to bind the ATD and inhibit the action of the NMDA receptor.

These inhibitor molecules are members of a class of compounds called phenylethanolamines which “have high efficacy and specificity and show some promise as neuroprotective agents without side effects seen in compounds that bind at the extracellular domain of other receptors,” Furukawa explains.

Now that his team has solved the structure of the ATD domain of the NR2B subunit, it becomes possible to proceed with rational design of a phenylethanolamine-like compound that can precisely bind the ATD within what Furukawa and colleagues call its “clamshell cleft,” based on the crystal structure they have obtained.

Additionally, many high protein diets are high in saturated fat and low in fiber, a combination that can increase cholesterol levels and raise the risk of heart disease and stroke.

High protein diets have also been shown to cause higher than normal calcium excretion through the urine, which over a prolonged period of time can increase the risk of osteoporosis and kidney stones. And a recent study suggests that a high protein diet may actually cause brain shrinkage and an increased “susceptibility to or progression of Alzheimer’s disease.”

The discovery was an unexpected one, found while studying the effects of different diets on mice bred to develop Alzheimer’s disease (AD). The mice were fed either a regular diet, high fat/low carb custom diet, high protein/low carb version or a high carb/low fat option. When the researchers looked at the brain and body weight of the mice, as well as plaque build-up and differences in the structure of several brain regions involved in the memory defect underlying AD, they were surprised to find that the brains of the mice fed a high protein/low carb diet were 5 percent lighter than all the others and the regions of their hippocampus were less developed.

The researchers theorize that the high protein diet may leave neurons more vulnerable to AD plaque. “High protein diets are used for weight control, and those diets sometimes combine high fat and high protein, which may be doubly damaging, if the high fat increases the accumulation of plaques and the high protein sensitizes nerve cells to the poison released by plaques,” said lead author Sam Gandy, a professor at The Mount Sinai School of Medicine and a neurologist at the James J. Peters Veterans Affairs Medical Center in New York. “Given the previously reported association of high-protein diet with aging-related neurotoxicity, one wonders whether particular diets, if ingested at particular ages, might increase susceptibility to incidence or progression of Alzheimer’s disease.”

Gandy believes the only way to know for sure if these findings have implications for the human brain is to perform prospective randomized double blind clinical diet trials. “This would be a challenging undertaking but potentially worthwhile. If there is a real chance that the ravages of Alzheimer’s disease might be slowed or avoided through healthy eating,” he said. “Such trials will be required if scientists are ever to make specific recommendations about dietary risks for Alzheimer’s disease.” Previous research has shown a Mediterranean-style low-calorie, low-fat diet rich in vegetables, fruits, and fish might delay the onset or slow the progression of AD.

AD is the most common type of dementia, affecting as many as 5.3 million Americans. Brain lesions, called amyloid plaques and tangles, accumulate, destroying brain cells, causing memory loss and problems with thinking and behavior severe enough to affect work, social life and even the ability to cope with everyday life. Over time, AD gets worse and is fatal. Currently, there is no cure for AD, but researchers around the world continue to search for better ways to treat the disease, delay its onset, or prevent it from developing.