Written and researched by Bob Murray, PhD
Latest News |
Back Issues | Get updates:
Children Sometimes Remember More Than Adults
Kids are smart, but curiously they are smart in different ways to adults. These findings run counter to what has been known for years from memory research -- namely, that memory develops from early childhood to young adulthood, with young adults having much better memory than children.
In one study, children were accurate 31 percent of the time in identifying pictures of animals they had seen earlier, while adults were accurate only 7 percent of the time. And the memory difference was not because adults already have their mind filled with appointments, to-do lists and other various grown-up issues.
The researchers found that memory accuracy of adults is hurt by the fact that they know more than children and tend to apply this knowledge when learning new information. “It's one case where knowledge can actually decrease memory accuracy,” said Vladimir Sloutsky, co-author of the study and professor and director of the Center for Cognitive Science at Ohio State University.
The findings appeared in the August 2004 edition of the journal Psychological Science.
The issue is how people perform a type of reasoning called induction, in which a person uses particular facts to reach general principles. One way of doing induction is by category. For example, if a person learns that a particular cat has a large brain, he can induce that other animals in the same category -- in this case “cats” -- also have large brains. This is the way most adults perform deduction.
But you can also do induction in other ways, such as by similarity. Using the same example, a person could induce that any animal that looks similar to the cat with a large brain, also must have a large brain. In this research, the findings showed that this is how children most often perform induction.
In one study, the researchers showed 77 young children (average age of 5 years) and 71 college students 30 pictures of cats, bears and birds. In some cases, the subjects were first shown a picture of a cat and informed that it had “beta cells inside its body.” They were then presented with the 30 pictures of animals, one at a time, and were asked whether each of the animals also had beta cells.
After this phase of the study was done, the participants were shown 28 pictures and asked whether each was “old” -- exactly the same picture shown previously -- or new. None of the participants knew they were going to be tested about their memory of the pictures. This is where the children were four times better than adults -- a 31 percent accuracy rate compared to only 7 percent for grown-ups.
The reason, Sloutsky said, was because children used similarity-based induction when they were examining the pictures the first time. When they were asked whether each pictured animal had “beta cells” like the first cat they were shown, they looked carefully to see if the animal looked similar to the original cat. On the other hand, the adults used category-based induction: once they determined whether the animal pictured was a cat or not, they paid no more attention to the details of the picture. So when they were tested later, the adults didn't know the pictures as well as the children.
“When people use category information, they will filter out unrelated information,” Sloutsky said. “The adults didn't care about a specific cat -- all they wanted to know was whether the animal was a cat or not. The children, though, were comparing similarity -- whether the animals looked like that first cat who had the beta cells. So they remembered specific items about each picture that helped them remember it later.“
In a second experiment, the researchers taught 5-year-old children to use category-based induction just like adults do. When they did that, the memory accuracy of the children dropped to the level of adults.
Read more in Psychological Science
Real Responses to False Memories
June 26, 2004
Over the years people have come to me and told me of highly stressful memories that, rationally, I know cannot possibly be real and so I read with great interest a story in the July 2004 issue of Psychological Science.
When people remember traumatic events, they'll show signs of their distress, like increased heart rate, sweating and muscle tension. These reactions are often seen as a testament to the authenticity of the memory--some have gone so far as to use physical reactions to memories to prove their validity, even when the memory is as far-fetched as ritual abuse by satanic cults. Yet this kind of stress reaction is the basis of the lie-detector tests.
Recently, though, a team from Harvard has challenged the significance of these reactions by looking into one of the most widely reported and least likely memories people claim: alien abductions.
The study was conducted by Richard McNally, Natasha Lasko, Susan Clancy, Michael Macklin, Roger Pitman and Scott Orr at Harvard University. The researchers recruited people who reported being abducted and had them describe the alien encounters as well as other stressful, happy, and neutral memories. The researchers converted these stories into 30-second audiotaped narratives and played them for the "abductees" while recording heart rate, sweat production, and facial muscle tension, three strong indicators of stress. The researchers also played the tapes for a control group of people who had no memories of alien encounters.
The researchers found that those who claimed to have been abducted had similarly strong reactions to the stressful narrative and the alien abduction, and weaker reactions to the happy and neutral narratives. The control group barely reacted to any of the stories.
When people believe they've been abducted by aliens, recalling their abduction can evoke reactions not unlike those evoked by a genuine memory that is stressful. This suggests that a person's reaction to a memory doesn't indicate whether the event happened, but only whether the memory, real or not, is traumatic.
Read more in Psychological Science
Top of page
Can We Believe Our Memories?
April 3, 2004
Previous research has suggested that really accurate memories may only last a few hours or less. Now a new study suggests that we can easily "remember" things that never happened at all!
In particular the use of photographs by psychotherapists as memory cues for the "recovery" of patients' possible childhood sexual abuse has been called into question by a Canadian study. It found that a "staggering" two-out-of-three participants accepted a concocted false grade-school event as having really happened to them when suggestions regarding the event were supplemented with a class photo.
"I was flabbergasted to have attained such an exceptionally high rate of quite elaborate false memory reports," says University of Victoria psychology professor Dr Stephen Lindsay. His NSERC-sponsored research is published in the March 2004 issue of Psychological Science.
Forty-five first year psychology students were told three stories about their grade-school experiences and asked about their memories of them. Two of the accounts were of real grade three to six events recounted to the researchers by the participant's parents. The third event was fictitious, but also attributed to the parents. It related how, in grade one, the subject and a friend got into trouble for putting Slime (a colourful gelatinous goo-like toy made by Mattel that came in a garbage can) in their teacher's desk.
The participants were encouraged to recall the events through a mix of guided imagery and "mental context re-instatement"--the mental equivalent of putting themselves back in their grade-school shoes. Half of the participants were also given their real grade one class photo, supplied by their parents.
The photo had a dramatic impact on the rate at which participants thought they had some memory of the imaginary Slime event. About a quarter of the participants without a photo said they had some memory of the false event. But 67% of those with a photo claimed to have a memory of the non-event--a rate that is double that found in any other study of false memory of autobiographical pseudoevents.
"The false memories were richly detailed," says Dr Lindsay, whose research focuses on memory and who co-authored the paper with a team from the University of Victoria and the Victoria University of Wellington, New Zealand.
Of those who claimed to remember the Slime event, most did so with just as much confidence as for the two real events. When asked which of the events didn't really happen, all but three of the participants said it was the Slime event. Even so, the fact that it was concocted elicited surprised reactions, including the comment, "No way! I remembered it! That is so weird!"
Dr Lindsay attributes the remarkably high rate of false memory to several factors. These include the plausibility of the Slime scenario (including that a friend was involved), the confidence inspired by the skilled "therapist" and the role of the photo as both a memory prod and seemingly corroborating piece of evidence.
"The findings support the general theoretical perspective that memories aren't things that are stored somewhere in your head," says Dr Lindsay. "Memories are experiences that we can have that arise through an interaction between things that really have happened to us in the past and our current expectations and beliefs."
He acknowledges that the use of suggestive memory "recovery" techniques by psychotherapists has declined since the late-1980s when it hit fad status. At the time, efforts to "recover" repressed childhood trauma memories were encouraged by such popular books as The Courage to Heal.
"But there still are people who use trauma-oriented memory approaches to therapy. And our results argue for caution in the use of any of these suggestive techniques," says Dr Lindsay. "Results like these support the concern that these kinds of techniques increase the likelihood that people will experience false memories."
For these reasons we caution against therapies that focus on retrieving specific memories and releasing them. Encouraging people to replay the memory repeatedly simply retraumatizes them without any therapeutic benefit. More useful is to examine relationship and behavior patterns in the present which mirror experiences in childhood and to create safe and trustworthy relationships that specifically counteract the trauma of the past. AF
Read more in Psychological Science
Top of page
Use it or Lose it Applies to Memory
August 13, 2003
In his old age, American humorist Mark Twain once mused that his mental faculties had decayed such that he could remember only things that never happened.
"When I was younger, I could remember anything, whether it happened or not," Twain wrote. "But my faculties are decaying now and soon I shall be so I cannot remember any but the things that never happened. It is sad to go to pieces like this, but we all have to do it."
Modern science has confirmed Twain's conjecture--research shows that memory skills tend to decline dramatically in old age, with decreasing levels of accuracy and increasing errors. However, new research from Washington University in St. Louis suggests age-related cognitive decay may not be as inevitable as Twain contended.
"Our study suggests that the failing memories of older adults, including their tendency to remember things that never happened, are not an inevitable consequence of aging," said Henry L "Roddy" Roediger III, study co-author and James S McDonnell Distinguished University Professor at Washington University.
In research presented at the American Psychological Association meeting in Toronto, Roediger provides evidence that false memories and other cognitive declines often associated with normal aging can be more directly linked to measurable declines in executive control functions in frontal brain lobes.
"We tested a group of adults with an average age of 75 years and found that about one out of four had managed to avoid the memory declines so common in older adults," said Roediger. "Older adults who maintain high frontal lobe function were shown to have memory skills every bit as sharp as a group of college students in their early 20s."
Roediger, a leading expert on human memory, has focused recent research on understanding cognitive processes behind the creation of false memories, also known as memory illusions. Human memory, he explains, is not a storehouse of crystal clear, video images available for immediate and 100 percent accurate recall. Instead, memories are recalled through a constructive process that retrieves sights, sounds, words and other seemingly pertinent information, weighs their relevance to the memory task at hand, and then weaves them into a "best available" representation of a past experience.
Veridical memories are those that generally conform to reality--memories that provide a relatively true and accurate representation of a past experience. False memories occur when we remember events differently from the way they occurred, or in the most dramatic cases, when we remember events that never happened. False memories often result when we mistakenly merge elements of various past experiences or when imagination is used to fill holes in a sketchy recollection.
This explains why many instances of "sexual abuse" or "alien abduction" can be traced to early invasive hospital experiences. This is not to deny, of course, that child sexual abuse is common and real.
"There has been a lot of research in recent years that suggests deterioration in the prefrontal cortex is linked to age-related declines in veridical memory, but this is the first study to firmly establish a similar link to increases in false memories," Roediger said. "The idea that frontal lobe decline is associated with susceptibility to false memories is relatively new."
Several theories exist for why false memories increase with age. One suggests that older adults fail to properly encode information as an event is experienced or have problems retrieving and sorting such details during recall--a problem known as source monitoring. A related theory suggest frontal lobe problems make it difficult for older adults to focus attention on the memory task at hand and to effectively place retrieved information in context. That is, frontal lobe functioning underlies the ability to monitor accurately the source of information, and when frontal
lobe declines, so does memory for the source of the events.
"If the frontal lobes are responsible for controlling attention or source monitoring, such that false memories can be distinguished from true memories, then we thought it possible that older adults with high frontal lobe function scores would not show greater false recall," Roediger said. "The idea here is that the increased susceptibility for memory illusions with older adults is carried by older adults with relatively low frontal lobe function. Our findings support this theory."
In other words, those who use their brain actively are less likely to be subject to false memories.
This story is based on a Washington University press release. The study has not yet been published.
Top of page
“I Remember It Well...”
May 25, 2003
Forget everything you’ve heard about forgetfulness. Researchers
at North Carolina State University believe that age-related declines in
memory and cognitive functioning may not be as pronounced as once believed.
Dr Thomas Hess, professor of psychology at NC State, says pessimistic
notions of changes in mental abilities associated with growing older may
in part be attributed to how early studies into cognition and aging were
conducted. His findings were outlined in a recent edition of Science
Hess’ research is part of a three-year study into stereotype threat,
aging and memory.
“Age differences that we’ve seen in previous memory studies
may not be entirely due to the biological changes associated with aging,”
Hess said. “They may also reflect older adults’ reactions
to the context in which we’ve tested people. When you look at older
adults in the everyday context in which they function, you get a very
different picture of their performance than when you look at them outside
of this context.”
Hess and his colleagues have argued that some of the age differences
that have been found in standard laboratory studies may be due to a situation
called “stereotype threat.”
Stereotype threat refers to an individual’s fear that his or her
behavior will reinforce a negative stereotype that exists about a group
to which one belongs. Researchers contend that individuals perform at
lower levels when they are placed in situations where they are aware that
their actions could confirm a negative stereotype.
Hess theorizes that since older adults are aware of the negative connotations
related to aging and memory, they experience heightened anxiety and evaluation
concerns that could negatively affect their performance on memory tests.
He examined the impact of stereotype threat on memory performance in
older adults in an experiment in which he manipulated the expectations
seniors had about their memories. Hess had older adults read mock newspaper
articles on recent findings related to aging and memory. Half of the articles
presented actual negative findings that suggested mental declines were
inevitable. The other half outlined more positive findings that implied
some memory skills were preserved with age and that mental declines could
After reading the articles, the subjects were given a basic memory test
in which they had to recall a list of words. Hess found that individuals
who read the positive article performed about 30 percent better on the
memory test than those who read the negative article.
To get a more realistic picture of cognitive functioning in older adults,
Hess and his researchers have emphasized social contexts and the real-life
settings in which seniors engage their minds in their memory studies.
In other experiments, Hess has discovered that older adults perform as
well or better than younger adults in tasks that involve making objective
decisions and assessing people’s character.
In one study, Hess found that older adults were just as adept as younger
adults at distinguishing between essential and extraneous information
when making decisions on issues that could impact their lifestyle.
In his experiment, adults ranging in age from 20 to 83 were asked to
evaluate a number of fictitious tax-increase proposals that were under
consideration by the state government. Before reading about the proposals,
subjects were presented with information about the legislator who supposedly
proposed the new tax programs. In half the cases, the legislator was presented
in a positive light, while in the other half the legislator was presented
in negative terms
The results showed that older adults performed on par with younger adults
in making decisions based on the merits of the tax program instead of
their perceptions of the legislator when the information was perceived
as relevant to their lives. In those situations that were perceived as
less relevant, however, older adults were more likely to be influenced
by extraneous information.
This suggests that the degree to which aging deficits in cognition are
observed is in part related to seniors’ perceptions of the task.
“We found that if the information was relevant to older adults,
they could focus their cognitive resources, tune out the irrelevant information
and make an informed decision,” Hess said. “They performed
almost exactly like younger adults. Older adults tended to focus on the
argument that was made rather than on who made it, which is the way we
would think an informed decision-maker would go about making a decision.”
In another study, Hess presented groups of older and younger adults with
positive and negative descriptions of fictitious individuals and asked
the subjects to evaluate the honesty and intelligence of those individuals.
Hess discovered that older adults were better than younger adults at judging
a person’s character and competence.
“Middle-aged and older adults make more complex judgments because
they focus on the most meaningful factors that could impact an individual’s
behavior,” Hess said. “Older people know what is important
in assessing character because of their years of experience and social
expertise. Young people haven’t had as much experience in the social
world, and they haven’t had as much time to learn about the many
factors that relate to behavior, so they tend to focus on qualities that
are somewhat superficial.”
“Negative stereotypes that exist about aging have negative effects
on people’s sense of wellbeing and the extent to which people fear
getting older. It’s quite evident that most people over the age
of 65 are functioning on their own, living on their own and doing quite
well. Although some basic aspects of cognitive ability decline as we age,
functioning is preserved in many contexts, and there are some areas that
actually improve as you get older.” These findings give us a more realistic
view of how people adapt to the aging process, and what their functioning
is like in everyday life
That older people are better at making some sorts of decisions was recognized
by our hunter-gatherer ancestors who looked for guidance and wisdom from
a council of elders. The study also reinforces an old theory of mine that
any study done on any creature--rabbit, rat or human--out of the context
of its normal life is inherently meaningless. BM
Read more in Science
Top of page
Emotions Influence Memory, Learning
November 12, 2002
Emotion, the basis for much of human expression, while yet still poorly understood, exerts definite influences on parts of the brain that control attention, perception and learning, a new report released recently suggests.
The report, which appears in the journal Science, traces the biological bases of emotions in findings that could have implications for treating mood and psychiatric disorders. It also could open windows to better understanding of neurological diseases such as Alzheimer's and dementia.
Researcher R J Dolan of the Institute of Neurology in London reviewed current medical literature about the brain and emotion and drew some key conclusions. For example, the "emotional machinery," as Dolan describes it, appears to connect directly to parts of the brain responsible for attention and absorbing new information. The same machinery also appears to be involved in forming memories and making decisions.
According to Dr Dolan, "The best studied examples of emotion influencing other brain regions are its effects on memory. This is mediated by influences on the hippocampus and early sensory processing regions. I suspect that there are few, if any, regions of the brain where the influence of emotion is not evident."
Another critical region of the brain, Dolan explains in his report, is the amygdala, an almond-shaped structure located within the limbic system. The amygdala is involved in registering emotion, particularly in response to danger. However, its connections to the visual cortex, which is found towards the back of the brain, and the hippocampus, which is behind and below the frontal lobes, permit the amygdala to process perception and memory.
"Emotion cannot easily be divorced from the concept of motivation and in this sense one can argue that emotion at some level is the engine of most forms of learning," Dolan said. For years, Dolan said, psychologists and psychiatrists and other physicians who study mental =llness have been apprehensive about delving into the understanding of emotion. "I think this has to do with the fact that for many years psychologists were uncomfortable with their (emotions') apparent subjective nature and the fact that emotions have bodily manifestations, as for example in a blush, that did not fit easily with a dominant information processing model of the mind," Dolan said.
Read more in Science
Top of page
Group Living is Better
February 25, 2002
If you are a loner, you'd better get yourself some close friends or else risk losing precious brain cells. That's the suggestion from a study into the brains of songbirds, which found that birds living in large groups have more new neurons and probably a better memory than those living alone.
How the brain stores long-term memory is a mystery, but some researchers think it involves permanent changes in the gene expression of brain cells. So animals like songbirds that have small brains and relatively long life spans would run out of neural "space" to store new memories if they didn't grow a constant supply of new cells. Songbirds do grow new neurons, though most of these die within three to five weeks and so can't store memories for long. But those that survive may provide space for new long-term memories.
Fernando Nottebohm of Rockefeller University in New York and his colleagues decided to study adult zebra finches to see whether their social conditions affect the survival rate of these new neurons. They injected the birds with a radioactive form of thymidine -- a marker to track new neurons -- and placed the birds in three different settings: alone, with another bird of the opposite sex, or in a large group of about 45 other birds. After 40 days the researchers examined three specific regions of the birds' brains to check development.
The researchers found that compared with the other birds, those living in large groups had about 30 per cent more new neurons in a region of the brain involved in sound processing. Even more impressively, the male zebra finches, who do all the singing, had twice as many new neurons in areas of the brain involved in communication when living in large groups. That could be simply because the birds are trying to remember every other bird's distinctive song, say the researchers in a paper to be published in the journal Behavioural Brain Research.
Researchers have noticed before that social animals such as elephants (and primates such as us) tend to have better memories than loners. But no one had actually seen a change in the survival of neurons caused solely by the number of companions.
"This is exciting stuff," says Arturo Alvarez-Buylla, an expert on neuronal growth from the University of California, San Francisco. "There is evidence that adult humans also produce new neurons in their brains, so these results raise the possibility that social interaction could help our neurons survive too," he says. And perhaps that would even boost our memories.
Human beings evolved in a hunter-gatherer band. It's no wonder that group living is better for us. BM
Read more in theNew Scientist
Top of page
Post Traumatic Stress Disorder (PTSD) and Depression Affect Memory
February 10, 2002
A study reported in the British Medical Journal suggests that those given the task of sorting out genuine asylum seekers from mere economic refugees may have their work cut out for them.
The authors highlight evidence that shows that people who have been through terrifying, life-threatening, experiences may develop faulty memories. What's more these memories become even less reliable with repeated interviews.
Yet it is discrepancies between accounts of an event that are often used to judge the credibility of asylum seekers.
The study found that the variations in the stories of those suffering from PTSD increased with length of time between interviews. More discrepancies occurred in details peripheral to the account than in details that were central to the account.
Under the terms of the 1951 United Nations convention on the status of refugees, a refugee is someone with a well founded fear of persecution on arbitrary grounds such as ethnicity or political opinion who cannot achieve protection in their home country. When they escape to a new country, their application for asylum is considered in the light of the information they can supply and any facts known about their country. There will often be little documentary evidence about the asylum seeker, and a legal decision on status by the authorities in the country of reception may rest on their credibility as a witness. Asylum seekers sometimes give accounts of persecution that differ with each telling.
Generally, the more detail a memory has, the more believable and convincing the account is. The gist of an autobiographical memory (central details) can be reconstructed from general (historical or schematic) knowledge, whereas details of a specific event (peripheral details) cannot. Recall of peripheral details is thus seen as a good way of distinguishing between "accurate recollection and plausible reconstruction." This is presumably the principle that, in part, guides state authorities' reliance on consistent details as an indication of credibility.
However, this view has been challenged in research on witnesses' evidence. Laboratory and field studies have shown that people recall more details that are central when an event has a high level of emotional impact, such as armed robbery, than when an event is emotionally neutral. Their recall of central details is, however, at the expense of their recall of peripheral.
Depression and anxiety, two sides of the same coin, are often associated with PTSD. Refugees often suffer from these states and both affect attention and memory. Clinically anxious people tend to focus on aspects of their environment that seem threatening rather than those that don't. Depressed people are biassed towards recalling negative personal memories in favor of positive ones. Patients with depression and with Post Traumatic Stress Disorder can have difficulties in retrieving specific autobiographical memories.
The researchers, who studied the effect of questioning on a group of Bosnians who had already been granted refugee status in the UK. They found that PTSD has a significant effect on the recall of peripheral events. Discrepancies (including the provision of new information) exist between autobiographical accounts of refugees given by the same individual on two occasions up to seven months apart. These findings cannot be explained on the grounds of intent to deceive. For refugees with high post-traumatic stress disorder, more discrepancies were found with longer times between interviews. (In the asylum process, there may be months or years between the original interview and an appeal hearing.) In addition, more discrepancies are found in details rated by participants as peripheral, compared with recollection of the central gist of the event. Discrepancies therefore cannot be taken as automatically implying fabrication.
Read more in the British Medical Journal
Top of page
Most Memory Aid Supplements Worthless
January 23, 2002
More and more people are rushing to buy memory-enhancing supplements, according to an article by Jane Brody in The New York Times. Most of the pills and potions they purchase are untried at best and otherwise worthless.
According to Brody, the Center for Science in the Public Interest, a Washington-based consumer organization, recently reviewed the research, or lack thereof, supporting claims for various "memory pills" and concluded for all but one product: "Don't waste your money."
The one exception, phosphatidylserine (sold as Brain Gum, CerebroPlex and Mind-Max) now being made from soybeans, looks promising in preliminary studies but costs about $90 a month, the center said in its newsletter, Nutrition Action.
Despite the attention given to Alzheimer's and other forms of dementia, these disorders, though devastating to individual sufferers and their families, afflict a minority of older people -- about 5% of people over 65. The incidence of some form of dementia rises to 40% of those over 80.
The good news, Brody says, is that scientists have recently demonstrated that while brain activity typically slows with age, normal healthy older people don't lose large numbers of nerve cells. (Neurologists used to think that after 30 you lost 20,000 neurons -- brain cells -- per day). In fact, at any age, with the right stimuli, new nerve cells and connections between them can form to enhance brain function.
The trick, as we should have learned from Winston Churchill and Grandma Moses -- who maintained their cognitive abilities to their dying days -- is to avoid or control the preventable diseases and behaviors that are known to impair brain function. These include high blood pressure and its attendant strokes (including mini-strokes that you may not even be aware of), heart disease, atherosclerosis and diabetes, all of which can impede circulation to the brain.
Also important is refraining from substances known to harm the brain. Top offenders are cigarette smoking and alcohol consumption beyond a daily or occasional drink. Excessive caffeine consumption may also be a problem. Tobacco smoke constricts blood vessels; caffeine slows blood flow to the brain and alcohol kills brain cells (although a little alcohol seems to be better at preserving brain function than none at all).
Recently the Institute for the Study of Aging and the International Longevity Center released a report recommending seven ways to keep one's mind functioning as effectively as possible, even into the 90's and beyond.
- Lifelong learning and training
Intellectual stimulation promotes brain growth -- use it or lose it. Take courses, read challenging books, take up a hobby, do crossword puzzles and memory exercises and play intellectually stimulating games (though as we recently reported, bingo works as well).
- Regular exercise
Several studies have now demonstrated the cognitive benefits of regular physical activity, even for those who may have physical limitations or emotional impairments. Activity promotes blood flow to the brain, and physically active older people have higher cognitive test scores and better reaction time.
- Daily activities
Especially helpful are activities that keep you involved with other people. You may choose to continue working or, if you retire, consider doing volunteer work, travelling to new places, gardening, knitting or crocheting and group activities like senior clubs and day trips. Clients and friends of ours in their eighties and beyond have joined choirs, become tour guides in museums, zoos etc. and even joined the staff at MacDonald's.
- Stress reduction
Animal studies have shown that chronic stress alters the structure of the brain and interferes with normal physiological functions that in turn can hurt cognitive function. Popular stress reduction techniques include physical activity, meditation and prayer.
Many older people are plagued by sleep disturbances. Failing to get enough sleep and especially enough REM (dream) sleep can impair cognitive function.
- Emotional stability
Studies indicate a distinct connection between emotional health and cognitive ability. Depression is common in older people and may actually result in injury to the brain. Especially at risk are those who have been widowed or who fail to pursue engaging activities after they retire.
- Good nutrition
Inadequate intake of a number of nutrients can impair brain function. Older people with higher intake of the antioxidant nutrients vitamins E and C and beta carotene (found in richly colored vegetables and fruits) have been shown to have better memories. Only about 15 percent of Americans over 65 consume what nutrition experts say is a good diet for older people.
Separately, one Canadian researcher, Dr David Wikenheiser, says that by following certain life-style changes you can take up to 15 years off your age in just three months. His advice: eat the right food, cut down on alcohol, drink enough water and get a good night's sleep.
Read more in The New York Times
For the Wikenheiser research
read more in BBC News
Top of page
Does the Brain Create New Cells?
December 8, 2001
A few years ago the world of neuroscience was rocked when researchers discovered that the brains of primates -- including humans -- could create new cells in parts of the brain, including the hippocampus (which plays a vital part in memory) and the neocortex (which is responsible for all the higher functions of the brain).
Now an intensive study by another group of scientists has disputed some of those findings. In particular they have not found any evidence that adult primates are able to create new neurons in the neocortex, according to the results of a study published in the journal Science.
The new findings, in a study funded by the National Institutes of Health, come from David Kornack, assistant professor of neurobiology and anatomy at the University of Rochester, and his former adviser, neuroscience pioneer Pasko Rakic of Yale.
"As a neuroscientist, oftentimes the first question I'm asked when I meet someone is, 'How can I get more brain cells?' I'm as interested in the question as everyone else," says Kornack. "It's now apparent that although some parts of the primate brain do acquire new neurons in adulthood, the neocortex is not among these regions."
For decades, scientists believed that adult humans and other primates such as monkeys are born pretty much with all the nerve cells, or neurons, in the brain that they'll ever have. However, in the last few years, several scientists equipped with new imaging techniques have reported growth of new neurons in adult primates including monkeys and humans in certain older parts of the brain, such as the hippocampus, which is key to memory, and the olfactory bulb, which is important for smell.
Two years ago, the idea took a giant step forward when researchers reported new neurons growing in the neocortex of adult monkeys. The neocortex -- the wrinkled outer layer of the brain -- is the most evolved part of the brain, controlling our most sophisticated behaviors such as language and planning.
The birth of new neurons in that part of the brain could have vast implications for human health and for understanding how the neocortex performs its duties.
However, in the new study Rakic and Kornack used the most sophisticated cell analysis techniques available and found no new neurons in the neocortex of adult monkeys despite painstaking analysis of thousands of new cells in the neocortex. The pair did find new neurons in the hippocampus and the olfactory bulb.
One upshot of the new findings, Kornack says, is that scientists should look to mechanisms besides neurogenesis (natural cell creation) to understand the workings of the neocortex, such as how we learn and store memories over a lifetime. The work could also affect the development of therapies that use adult stem cells to replace neurons lost to brain injury or neurodegenerative diseases such as Parkinson's or Alzheimer's.
"If we can find out what allows stem cells in those few restricted brain regions to continue producing neurons into adulthood, perhaps we can mimic that magic in other areas of the brain -- such as the neocortex -- that can suffer neuronal loss but don't normally make neurons," says Kornack.
New Memories for Old
Separately, the journal Neuron reports that scientists have found existing memories may be erased in our brain by a process involving the generation of new neurons. This clearance might be important to make room for the acquisition of new memories.
The research team, led by Joe Tsien of the Department of Molecular Biology at Princeton University, generated mice that lack a protein called presenilin-1 throughout much of the brain. Mutations in presenilin-1 are responsible for the majority of cases of early-onset Alzheimer's disease, but the function of the protein in the context of the normal CNS is poorly understood.
These mice were viable and grew normally, but the researchers observed that after spending time in a rich, stimulating environment filled with diversions and mouse toys, the brains of presenilin-1 mutant mice generated fewer new neurons than the brains of normal mice.
Tsien and his colleagues initially thought that this reduced neurogenesis might cause learning deficits, but, after months of testing, none could be detected. The researchers did observe, however, that time spent in an enriched environment generally enhanced the retention of recent learning.
To their surprise, they also found that some newly formed memories were harder to erase in the mice lacking presenilin-1 than in the control mice. This suggested to the authors that generation of new neurons is important for the memory-clearance process.
Memory retention ordinarily seems like a good thing. However, as Tsien points out, adding new neurons to existing networks may potentially disrupt, rather than improve, the function of these networks.
These findings raise a possibility that chronic abnormalities in this clearance process may contribute to the devastating memory disorder associated with Alzheimer's disease. In addition, they raise a potential cautionary note about the therapeutic use of neural stem cell transplantation for neurodegenerative disorders.
We shall follow the debate over the neurology and ethics of neurogenesis and stem cell research with interest and keep you up to date. BM
Read more in Uniscience online
Top of page
Check our event schedule for workshops and seminars.
About the Author
Dr Bob Murray is a widely published psychologist and expert on emotional health and optimal relationships. Together with his wife and long-term collaborator Alicia Fortinberry, he is founder of the highly successful Uplift Program, and author of Raising an Optimistic Child (McGraw-Hill, 2006) and Creating Optimism (McGraw-Hill, 2004).
Do you like our site? Recommend this page to a friend!