Showing posts with label Alzheimer's. Show all posts
Showing posts with label Alzheimer's. Show all posts

Friday, March 15, 2019

Researchers find clues that depression may speed brain aging

In continuation of my updates on depression and its causes
Memory and thinking skills naturally slow with age but now scientists are peeking inside living brains to tell if depression might worsen that decline—and finding some worrisome clues. Depression has long been linked to certain cognitive problems, and depression late in life even may be a risk factor for the development of Alzheimer's. Yet how depression might harm cognition isn't clear.
One possibility: Brain cells communicate by firing messages across connections called synapses. Generally, good cognition is linked to more and stronger synapses. With cognitive impairment, those junctions gradually shrink and die off. But until recently, scientists could count synapses only in brain tissue collected after death.
Yale University scientists used a new technique to scan the brains of living people—and discovered that patients with depression had a lower density of synapses than healthy people the same age.
The lower the density, the more severe the depression symptoms, particularly problems with attention and loss of interest in previously pleasurable activities, Yale neuroscientist Irina Esterlis said Thursday at a meeting of the American Association for the Advancement of Science. She wasn't studying just seniors but a range of ages including people too young for any cognitive changes to be obvious outside of a brain scan—on the theory that early damage can build up.
"We think depression might be accelerating the normal aging," she said.
Her studies so far are small. To prove if depression really worsens that decline would require tracking synaptic density in larger numbers of people as they get older, to see if and how it fluctuates over time in those with and without depression, cautioned Jovier Evans, a staff scientist at the National Institute on Mental Health.
Esterlis is planning a larger study to do that. It's delicate research. Volunteers are injected with a radioactive substance that binds to a protein in the vesicles, or storage bins, used by synapses. Then during a PET scan, areas with synapses light up, allowing researchers to see how many are in different regions of the brain.
Esterlis said there are no medications that specifically target the underlying synapse damage.
But other brain experts said the preliminary findings are a reminder of how important it is to treat depression promptly, so people don't spend years suffering.
"If your mood isn't enough to make you go and get treated, then hopefully your cognition is," said Dr. Mary Sano, who directs the Mount Sinai Alzheimer's Disease Research Center in New York and wasn't involved in the new research.
Still, she cautioned that normal cognitive aging is a complicated process that involves other health problems, such as heart disease that slows blood flow in the brain. It might be that depression, rather than worsening synaptic decline, just makes it more obvious, Sano noted.
With depression "at any age, there's a hit on the brain. At an older age the hit may be more visible because there may already be some loss," she explained.
Indeed, another way the brain ages: The blood-brain barrier, which normally protects against infiltration of damaging substances, gradually breaks down, Daniela Kaufer of the University of California, Berkeley, told the AAAS meeting. That triggers inflammation, setting off a cascade that can cause cognitive impairment. Her lab found a specific molecular culprit and is developing, in studies with mice, a way to block the inflammatory damage.
The University of Toronto's Etienne Sibille is developing a compound to target yet another piece of the puzzle, brain receptors that are impaired with both aging and depression. Mouse studies showed it could reverse stress-induced memory loss, he said. Any human testing is at least several years away.

Wednesday, October 14, 2015

TUM scientists develop molecules that could pave way for new treatments to fight Alzheimer's, diabetes

When proteins change their structure and clump together, formation of amyloid fibrils and plaques may occur. Such 'misfolding' and 'protein aggregation' processes damage cells and cause diseases such as Alzheimer's and type 2 diabetes. A team of scientists from the Technical University of Munich (TUM) headed by Professor Aphrodite Kapurniotu have now developed molecules that suppress protein aggregation and could pave the way for new treatments to combat Alzheimer's, type 2 diabetes and other cell-degenerative diseases.

The scientists designed and studied 16 different peptide molecules in order to find out which of them are able to impede the 'clumping' of the proteins amyloid beta (Aß) and islet amyloid polypeptide (IAPP), which are associated with Alzheimer's and type 2 diabetes.

The molecules were designed on the basis of scientific work that shows that the Aß and IAPP proteins interact with each other, and that this 'cross-amyloid interaction' suppresses their clumping. The researchers selected short sequences of the IAPP protein that correspond to the key regions involved in the interaction with the Alzheimer's protein. These "hot segments" were then chemically linked to each other by using specific peptide segments as 'linkers' in order to mimic and optimize the IAPP cross-amyloid interaction surface.

Ref :

Wednesday, April 15, 2015

Researchers uncover mechanism by which anti-inflammatory processes may cause Alzheimer's

Inflammation has long been studied in Alzheimer's, but in a counterintuitive finding reported in a new paper, University of Florida researchers have uncovered the mechanism by which anti-inflammatory processes may trigger the disease.

This anti-inflammatory process might actually trigger the build-up of sticky clumps of protein that form plaques in the brain. These plaques block brain cells' ability to communicate and are a well-known characteristic of the illness.

The finding suggests that Alzheimer's treatments might need to be tailored to patients depending on which forms of Apolipoprotein E, a major risk factor for Alzheimer's disease, these patients carry in their genes.

The researchers have shown that the anti-inflammatory protein interleukin 10, or IL-10, can actually increase the amount of apolipoprotein E, or APOE, protein -- and thereby plaque -- that accumulates in the brain of a mouse model of Alzheimer's, according to the study, published online today (Jan. 22) in the journal Neuron.

Tuesday, August 20, 2013

Scientists ID compounds that target amyloid fibrils in Alzheimer's, other brain diseases

The UCLA researchers, led by David Eisenberg, director of the UCLA-Department of Energy Institute of Genomics and Proteomics and a Howard Hughes Medical Institute investigator, report the first application of this technique in the search for molecular compounds that bind to and inhibit the activity of the amyloid-beta protein responsible for forming dangerous plaques in the brain of patients with Alzheimer's and other degenerative diseases.

o identify natural and synthetic compounds that might prevent the aggregation and toxicity of amyloid fibrils. Such studies have revealed that polyphenols, naturally occurring compounds found in green tea and in the spice turmeric, can inhibit the formation of amyloid fibrils. In addition, several dyes have been found to reduce amyloid's toxic effects, although significant side effects prevent them from being used as drugs. 

Armed with a precise knowledge of the atomic structure of the amyloid-beta protein, Jiang, Eisenberg and colleagues conducted a computational screening of 18,000 compounds in search of those most likely to bind tightly and effectively to the protein.
Those compounds that showed the strongest potential for binding were then tested for their efficacy in blocking the aggregation of amyloid-beta and for their ability to protect mammalian cells grown in culture from the protein's toxic effects, which in the past has proved very difficult. Ultimately, the researchers identified eight compounds and three compound derivatives that had a significant effect.
While these compounds did not reduce the amount of protein aggregates, they were found to reduce the protein's toxicity and to increase the stability of amyloid fibrils  a finding that lends further evidence to the theory that smaller assemblies of amyloid-beta known as oligomers, and not the fibrils themselves, are the toxic agents responsible for Alzheimer's symptoms.
The researchers hypothesize that by binding snugly to the protein, the compounds they identified may be preventing these smaller oligomers from breaking free of the amyloid-beta fibrils, thus keeping toxicity in check...