Posts tagged ‘memory’
A clue to why memory deteriorates with age has been found by US researchers.
Experiments on mice suggested low levels of a protein in the brain may be responsible for memory loss.
It is hoped the discovery could lead to treatments to reverse forgetfulness, but it is a big leap from the mouse to a human brain.
The study, published in the journal Science Translational Medicine, said age-related memory loss was a separate condition to Alzheimer’s disease.
The team at Columbia University Medical Centre started by analysing the brains of eight dead people, aged between 22 and 88, who had donated their organ for medical research.
They found 17 genes whose activity level differed with age. One contained instructions for making a protein called RbAp48, which became less active with time.
Young mice genetically engineered to have low RbAp48 levels performed as poorly as much older mice in memory tests.
Using a virus to boost RbAp48 in older mice appeared to reverse the decline and boosted their memory.
One of the researchers, Prof Eric Kandel, said: “The fact that we were able to reverse age-related memory loss in mice is very encouraging.
“At the very least, it shows that this protein is a major factor, and it speaks to the fact that age-related memory loss is due to a functional change in neurons of some sort. Unlike with Alzheimer’s, there is no significant loss of neurons.”
It is still not know what impacted adjusting levels of RbAp48 in the far more complex human brain or even it if is possible to manipulate levels safely.
Dr Simon Ridley, from Alzheimer’s Research UK, said: “While the findings may seem clear cut from these studies, in reality people reaching older age may well have a combination of changes happening in the brain – both age-related and those involved in the early stages of Alzheimer’s.
“Separating early changes in Alzheimer’s from age-related memory decline in the clinic still presents a challenge, but understanding more about the mechanisms of each process will drive progress in this area.”
Researchers looked at how proteins powered brain function and memory
A lack of a protein in Down’s syndrome brains could be the cause of learning and memory problems, says a US study.
Writing in Nature Medicine, Californian researchers found that the extra copy of chromosome 21 in people with the condition triggered the protein loss.
Their study found restoring the protein in Down’s syndrome mice improved cognitive function and behaviour.
The Down’s Syndrome Association said the study was interesting but the causes of Down’s were very complex.
Prof Huaxi Xu, senior author of the study from the Sanford-Burnham Medical Research Institute, said that in experiments on mice they discovered that the SNX27 protein was important for brain function and memory formation.
In Down’s syndrome, we believe lack of SNX27 is at least partly to blame for developmental and cognitive defects.”
Prof Huaxi XuSanford-Burnham Medical Research Institute
Mice with less SNX27 had fewer active glutamate receptors and therefore had impaired learning and memory.
The SNX27-deficient mice shared some characteristics with Down’s syndrome, so the researchers looked at human brains with the condition.
This confirmed their findings in the lab – that people with Down’s syndrome also have significantly lower levels of SNX27.
Neurons from a normal mouse (left) are longer and fuller than neurons from a mouse lacking SNX27 (right)
“So, in Down’s syndrome, we believe lack of SNX27 is at least partly to blame for developmental and cognitive defects,” Prof Xu said.
In the lab, the research team increased the levels of the protein in mice brains to see if the problem could be resolved.
“Everything goes back to normal after SNX27 treatment,” said Xin Wang, a graduate member of the research team.
“First we see the glutamate receptors come back, then memory deficit is repaired in our Down’s syndrome mice.”
But Prof Xu cautioned that science still had work to do to develop a safe technique of delivering genes into the human brain.
The researchers are now screening small molecules to look for those that might increase SNX27 production or function in the brain.
Carol Boys, chief executive of the Down’s Syndrome Association, said they were following the development of many biomedical research studies into Down’s syndrome with interest.
“This particular study is of interest; however, the genetic causes of Down’s syndrome are very complex and we are still a long way away from the development of therapeutic treatments that might lead to improvement to cognition in people with Down’s syndrome.”
She also said they were mindful of the ethical issues that such treatments might raise for people with Down’s syndrome and their families.
Nicotine ‘may aid memory for in early dementia’
By Michelle Roberts Health reporter, BBC News
The patches appear to give a cognitive boost to people with mild memory impairment.
The findings, published in the journal Neurology, come from a small study of 67 people over a period of six months.
Experts say the results are not conclusive, merely hinting of a benefit and do not mean people should smoke.
The health risks of smoking massively outweigh any potential nicotine benefits. And nicotine is known to be addictive.
Longer and larger studies are now needed to fully assess nicotine’s effect on memory and whether it might point the way to new treatments for Alzheimer’s disease and other forms of dementia, they say.
There are some 820,000 people in the UK living with dementia. Although some drugs are already available that can lessen some of the symptoms of the disease, there is no cure for this progressive disorder.
Memory and cognition are some of the first functions that begin to fail in a person with dementia.
We do not know whether benefits persist over long periods of time and provide meaningful improvement”
Lead researcher Dr Paul Newhouse
They may find it difficult to recall recent events or facts or become increasingly confused, even when in familiar surroundings, for example.
Scientists have known for some time that the brain contains receptors that respond to nicotine and that a number of these are lost in Alzheimer’s.
The latest work found that six months of treatment with nicotine patches appeared to improve how well individuals with “pre-dementia” or mild cognitive impairment (MCI) performed on tests designed to assess memory, attention and response times.
After six months of treatment, the nicotine-treated group regained 46% of normal performance for age on long-term memory, whereas the placebo group worsened by 26% over the same time period.
However, the findings were not statistically significant – a measure investigators need results to meet in order to rule out any chance findings.
The scientists say more studies are now needed to confirm their preliminary findings.
Lead author Dr Paul Newhouse, of Vanderbilt University School of Medicine in Nashville, said: “This study provides strong justification for further research into the use of nicotine for people with early signs of memory loss.
“We do not know whether benefits persist over long periods of time and provide meaningful improvement.”
Derek Hill, professor of medical imaging science at University College London, said the study gave some exciting evidence that mild memory problems might be treatable before they develop into full blown dementia.
But he added: “Nicotine is just one of the existing or experimental drugs that could prove beneficial for this patient group. It should encourage more investment into research into possible treatments.
“It is quite likely that no treatment will help everyone – and so new diagnostic tests to match patients to treatments may be also needed to tackle dementia.”