12 January 2014
Sleep 'cleans' the brain of toxins
Memory 'more consistent with age'
Coffee 'may reverse Alzheimer's'
A US study has raised the possibility that we may one day rely on caffeine to boost memory as well as to wake up.
The research, published in Nature Neuroscience, tested the memories of 160 people over 24 hours.
It found those who took caffeine tablets, rather than dummy pills, fared better on the memory tests.
But experts warned people to remember caffeine could cause negative effects, such as jitteriness and anxiety.
The Johns Hopkins University study involved people who did not regularly eat or drink caffeinated products.
Saliva samples were taken, to check base levels of caffeine, then participants were asked to look at a series of images.
Five minutes later they were given either a 200-milligram caffeine tablet - equivalent to the caffeine in a large cup of coffee, according to the researchers - or a dummy pill.
Saliva samples were taken again one, three and 24 hours later.
The next day, both groups were also tested on their ability to recognise the previous day's images.
Twenty-four hours may not sound like a long time, but it is in terms of memory studies. Most "forgetting" happens in the first few hours after learning something.
People were purposely shown a mixture of some of the initial tranche of images, some new - and some that were subtly different.
Being able to distinguish between similar, but not identical items, is called pattern separation and indicates a deeper level of memory retention.
More members of the caffeine group were able to correctly identify "similar" images, rather than wrongly saying they were the same.
"Our study suggests that 200mg of coffee is beneficial to those who do not regularly ingest caffeine”
Prof Michael Yassa Johns Hopkins University
Prof Michael Yassa, who led the study, said: "If we used a standard recognition memory task without these tricky similar items, we would have found no effect of caffeine.
"However, using these items requires the brain to make a more difficult discrimination - what we call pattern separation, which seems to be the process that is enhanced by caffeine in our case."
Only a few previous studies have been carried out into caffeine's effect on long-term memory, and those that have been done generally found little effect.
This study was different because people took the caffeine after, rather than before, they had seen and attempted to memorise the images.
The team now want to look at what happens in the hippocampus, the "memory centre" of the brain, so they can understand caffeine's effect.
Moderation But Prof Yassa said their findings do not mean people should rush out and drink lots of coffee, eat lots of chocolate - or take lots of caffeine pills.
"Everything in moderation. Our study suggests that 200mg of coffee is beneficial to those who do not regularly ingest caffeine.
"But we also show an inverted U-shape dose response suggesting that higher doses may not be as beneficial.
If you take too much caffeine there could be negative consequences for the body”
Dr Ashok Jansari University of East London
"Keep in mind that if you're a regular caffeine drinker this amount may change."
He added: "There are of course health risks to be aware of.
"Caffeine can have side effects like jitteriness and anxiety in some people. The benefits have to be weighed against the risks."
Dr Anders Sandberg from the Future of Humanity Institute at the University of Oxford, said: "The paper demonstrates that giving caffeine after seeing images does improve recognition of them 24 hours later, supporting the idea that it helps the brain consolidate the learning.
"However, there was no straight improvement in recognition memory thanks to caffeine. Rather, the effect was a small improvement in the ability to distinguish new images that looked like old, from the real old images."
He added: "Caffeine may still be helpful for paying attention to what you are studying and hence help your encoding, but the best way of boosting consolidation is sleep - which might be a problem in this case, if you take the caffeine too close to bedtime.
Dr Ashok Jansari, from the University of East London's school of psychology, said caffeine appeared to "sharpen" memory, rather than actually making it better.
He said: "I would definitely not advise that people start taking in as much caffeine as possible since in terms of memory anything above 200mg may not help much and if you take too much caffeine there could be negative consequences for the body."
Coffee 'may reverse Alzheimer's'
5 July 2009
A possible treatment for dementia?
Drinking five cups of coffee a day could reverse memory problems seen in Alzheimer's disease, US scientists say.
The Florida research, carried out on mice, also suggested caffeine hampered the production of the protein plaques which are the hallmark of the disease. Previous research has also suggested a protective effect from caffeine. But British experts said the Journal of Alzheimer's disease study did not mean that dementia patients should start using caffeine supplements. The results are particularly exciting in that a reversal of pre-existing memory impairment is more difficult to achieve Dr Gary Arendash University of South Florida The 55 mice used in the University of South Florida study had been bred to develop symptoms of Alzheimer's disease. First the researchers used behavioural tests to confirm the mice were exhibiting signs of memory impairment when they were aged 18 to 19 months, the equivalent to humans being about 70. Then they gave half the mice caffeine in their drinking water. The rest were given plain water. The mice were given the equivalent of five 8 oz (227 grams) cups of coffee a day - about 500 milligrams of caffeine. The researchers say this is the same as is found in two cups of "specialty" coffees such as lattes or cappuccinos from coffee shops, 14 cups of tea, or 20 soft drinks. When the mice were tested again after two months, those who were given the caffeine performed much better on tests measuring their memory and thinking skills and performed as well as mice of the same age without dementia. Those drinking plain water continued to do poorly on the tests. In addition, the brains of the mice given caffeine showed nearly a 50% reduction in levels of the beta amyloid protein, which forms destructive clumps in the brains of dementia patients. Further tests suggested caffeine affects the production of both the enzymes needed to produce beta amyloid. The researchers also suggest that caffeine suppresses inflammatory changes in the brain that lead to an overabundance of the protein. Earlier research by the same team had shown younger mice, who had also been bred to develop Alzheimer's but who were given caffeine in their early adulthood, were protected against the onset of memory problems. 'Safe drug' Dr Gary Arendash, who led the latest study, told the BBC: "The results are particularly exciting in that a reversal of pre-existing memory impairment is more difficult to achieve. "They provide evidence that caffeine could be a viable 'treatment' for established Alzheimer's disease and not simply a protective strategy. "That's important because caffeine is a safe drug for most people, it easily enters the brain, and it appears to directly affect the disease process." The team now hope to begin human trials of caffeine to see if the mouse findings are replicated in people. They do not know if a lower amount of caffeine would be as effective, but said most people could safely consume the 500 milligrams per day. However they said people with high blood pressure, and pregnant women, should limit their daily caffeine intake. Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: "In this study on mice with symptoms of Alzheimer's, researchers found that caffeine boosted their memory. We need to do more research to find out whether this effect will be seen in people. "It is too early to say whether drinking coffee or taking caffeine supplements will help people with Alzheimer's. Neil Hunt, chief executive of the Alzheimer's Society, said previous research into caffeine had suggested it could delay Alzheimer's disease and even protect against vascular dementia. "This research in mice suggests that coffee may actually reverse some element of memory impairment. "However much more research is needed to determine whether drinking coffee has the same impact in people. "It is too soon to say whether a cup of coffee is anything more than a pleasant pick me up."