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An actress portraying a zombie poses for a picture to promote "The Walking Dead."

A figure, mouth agape, staggers across a barren landscape, moaning incoherently. Add some jerky movements and a dazed expression, and we recognize it as a zombie.

Or is it someone infected with rabies? If Brandon Brown has his way, our current national obsession with zombies will help us learn more about public health issues like rabies and other little understood conditions.

“You can almost see zombies as a link or metaphor,” explains Brown, author of the paper “Zombies—A Pop Culture Resource for Public Health,” which was published online in the journal Emerging Infectious Diseases.

It’s not the first time zombies have been used as metaphor for public health issues. Back in 2011, Dave Daigle and colleagues wrote a wildly popular blog post about preparing for the coming zombie apocalypse as a way to encourage the public to think about disaster preparedness. So many people clicked, the CDC website crashed. “Zombies are a lot sexier than our typical health topic,” explains Maggie Silver, one of the brains behind that zombie campaign.

Brown stumbled across that post, which got him thinking about other ways zombies could educate people about public health.  

“I had previous interest in zombies because of ‘The Walking Dead’ and ‘Night of the Living Dead,’” Brown says. “I thought I could build upon it and look at other public health related issues.”

He examined the history of zombies and soon realized the walking dead share similarities with rabies. “With both of them, there is a stage where you are trying to bite people,” deadpans Daigle.

While rabies accounts for few, if any deaths, in the United States due to prophylaxis and vaccinations, it remains a scourge in developing countries. While Brown writes that what we know about how the zombie virus moves through the body is, sadly, fictional, we know that rabies proliferates after an infected creature bites someone and the virulent saliva spreads through the blood stream. Both zombies and rabid people tend to be slack-jawed and rabid people salivate a lot, making it easier to spread the disease. And both can become violent and aggressive. Rabies makes it difficult to swallow, meaning victims’ voice boxes spasm and they cannot talk. Most zombies typically groan (though some have been known to wail “braaaaains”).     

Brown also recognized that zombies could help explain often misunderstood neurological conditions such as Alzheimer’s and Parkinson’s diseases. Using the zombie example to explain the neurodegenerative disorders could help people better understand these complex and frightening diseases. Both zombies and Parkinson’s patients experience muscle rigidity, tremors and slowness, for example, and the changes someone undergoes with such a disease can seem as terrifying as fictional monsters.

“I think one of the major issues with understanding Alzheimer’s and Parkinson’s is that there is a real lack of interest unless people have it in their own lives … I think it’s the same with rabies,” he says. 

Of course, Brown adds that with this tactic, public health administrators must take great caution not to stigmatize those with Alzheimer’s or Parkinson’s. “I think we can stigmatize zombies all we want, but have to be careful with others,” he says.  

Related:

How to prepare for the zombie apocalypse? CDC has you covered

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While most of us have trouble remembering the details of even the most important days of our lives, college student Aurelien Hayman can recall every moment of his life, no matter how mundane.

Give him a year and a date and he can tell you what day of the week it was, what the weather was like -  even what he ate for breakfast.

“I can just remember these sorts of things without even trying – and without them having any importance,” Hayman told TODAY. “I just remember them.”

Hayman is one of a small group of people who have extraordinary ability to recall specific details of events, even ordinary days, that happened years ago. TODAY has interviewed several of them over the years, including actress Marilu Henner, who stunned Meredith Vieira in an interview with the vivid recall of the last time they’d brushed past one another.

Though the phenomenon has only recently been identified, scientists have given this special kind of memory a name: Highly Superior Autobiographical Memory, or HSAM.

Because it’s so new, there’s been little research on the topic. But in July of this year a study of 11 people with HSAM was published in the journal Neurobiology of Learning and Memory.

Researchers from the University of California, Irvine, interviewed  11 people with HSAM and scanned their brains. And while the researchers did identify nine brain areas that seemed to be different in size and shape from those of volunteers with typical memories, what really caught the researchers’ attention were the differences in behavior.  

People with HSAM tend to obsess over events (even mundane ones) more than the average person. They ruminate over what happened during the day and organize everything in their minds over and over again.

In fact, they often report “habitually recalling their memories, a seemingly compulsive tendency,” noted Aurora K.R. LePort and her colleagues. “Every night before bed one participant recalls what occurred on that day X number of years ago. Another recalls, while stuck in traffic, as many days as possible from a certain year.”

Memory expert Dr. Gary Small believes we should study people like Hayman and Henner to help people who are losing their memory due to disease or old age.

“We are involved in memory training techniques to teach people to try to improve their memories – and of things that individuals with extraordinary biographical memory seem to do instinctively,” said Small, director of the Longevity Center at the University of California, Los Angeles, and author of “The Alzheimer’s Prevention Program: Keep Your Brain Healthy for the Rest of Your Life.”

“I think that probably their brains are wired so that they can naturally do what we teach others to do to improve their memories: focusing attention, creating associations and giving those associations meaning.”

While a perfect memory might seem like a gift, some people find it a real burden.

Jill Price, 46,  wishes she couldn’t remember everything quite so well. She is plagued by her inability to escape unhappy memories that are so detailed that they feel like they just happened.

“Thinking about something from 20 years ago that means absolutely nothing to me today, but still bothers me or still upsets me,” Jill said.  It’s like yesterday. It really is.”

But for Hayman and most of the people in the new study, HSAM is a gift.            

“As a group they view their autobiographical memory ability as a positive attribute,” LePort and her colleagues concluded.

Hayman himself only recently realized that his memory was out of the ordinary.

“Now that I know it’s something special, I think I’ll sort of value it more,” he told TODAY.

Related stories:

Where are my keys? Expert tips for remembering

Joy Bauer's memory-boosting smoothie

Marilu Henner talks about her steel-trap memory

Scientists have long assumed that fading memories are just a normal part of aging. But a new study suggests that certain 80-somethings can remember every bit as well as people much younger.

Researchers from Northwestern University found that these mentally sharp octogenarians, dubbed SuperAgers, also have brains that look very much like those of people in middle-age, according to the study published in the Journal of International Neuropsychological Society.

For the new study, researchers used MRIs to look at the thickness of the outer layer of the brain, a region called the cortex, in SuperAgers, normally aging 80-somethings, and healthy 50- to 65-year-olds.

What they found was intriguing – the SuperAgers had brains that looked very much like those of the younger people in the study and in some ways looked even healthier. 

"We were very surprised at that," says study co-author Emily Rogalski, an assistant research professor at the cognitive neurology and Alzheimer's disease center at the Northwestern University Feinberg School of Medicine

"When we looked at cortical thickness, we were very shocked to see that even with a 20- to 30-year age gap, there was seemingly no difference in the cortical thickness," she says. "In normally aging 80-year-olds, you see quite a bit of cortical thinning, even among those who are still performing normally for their age."

The cortex is key since it's involved in memory, attention, and complex thinking, also known as executive function.

Rogalski and her colleagues tested the memories and cognitive skills of 12 Chicago-area SuperAgers and 14 middle-aged volunteers. They then scanned all 26 with a 3D MRI machine and compared both groups of scans to images from normally aging 80-somethings that came from a national data bank.

Finding a group of SuperAgers was no easy task, however.

While plenty of 80-somethings showed up at the lab saying their memories were great, most didn’t remember as well as healthy middle-aged people do.

"We weren't even sure if we would be able to find any SuperAgers since we set the bar so high," says Rogalski. "They had to be as good as 50- to 65-year olds. We screened 300 people who thought they had good memories and found 30 SuperAgers."

And the MRIs showed why the 30 SuperAgers were so mentally sharp.

Rogalski found the SuperAgers' cortexes were as thick as those in people 20 to 30 years younger.

Experts believe that shrinking cortexes are a sign that cells are shriveling and dying with age - sometimes killed off by the same abnormal proteins as you see in Alzheimer's brains. One finding that really surprised Rogalski and her colleagues: a region deep in the brain, called the anterior cingulate was actually larger in SuperAgers than it was in middle-aged folks.

The anterior cingulate is very important for attention. Studies have shown that one of the reasons memory fails as we age is that we can't focus as well as we did when we were younger.

"If I were to tell you ten things you need to pick up at the grocery store and then the phone rang and you got distracted talking to your best friend you'd probably find it hard to remember those ten things when you got to the store," Rogalski explains. "That wouldn't mean your memory was bad, but rather, that you weren't able to focus on the task."

Rogalski hopes the new research on SuperAgers may help scientists unlock the secrets of these "youthful brains" and find ways to protect us against from age-related damage.

"This is the first step in a new way of looking at this - a road less traveled in aging research," she says. "Instead of looking at what is going wrong with the brain, we want to know what is going right."

As for why some people are SuperAgers and some aren't, the research team can't provide any answers at this point. It could be all related to genetics or a combination of genes and the environment: no clues popped up during the SuperAger's interviews that set them apart from people who had aged normally.

But the question of whether there's something we can do to keep mentally sharp is something Rogalski is hoping she'll be able to answer as she continues to study the SuperAger phenomenon.

Related: 

• Seniors say they sleep better than young adults
• Real 'Benjamin Button'? Stem cells reverse aging in mice

By Andrew Winner 

There are those who say there’s a use for every little thing in this world, no matter how vile or off-putting. An enterprising dentist is doing his part to prove that's true. Japanese dental researchers have found that halitosis -- that is, bad breath -- is an ideal incubator for cultivating hepatic (liver) cells.

In a finding that could have far-reaching impacts on diseases such as Alzheimer’s and Parkinson’s, stem cells harvested from human dental pulp became liver cells at an astonishing rate when incubated with hydrogen sulphide, the chemical compound responsible for bad breath.

Talk about the ultimate silver lining. The study was published Monday in IOP Publishing's Journal of Breath Research.

Stem cell therapy treats damaged tissue by introducing new cells, but it can sometimes be difficult to safely and effectively produce these new cells. Study author Dr. Ken Yagaeki and his team at Nippon Dental University believe the use of stem cells from dental pulp could eventually replace existing methods of stem cell production, two of which use human bone marrow and fetal bovine serum as source material. In fact, Yagaeki went out on a limb to show that dental pulp is a viable source of stem cells.

For Yagaeki, observing the resilience of teeth plagued by cavities made him wonder if there weren’t more stem cells in dental pulp than previously thought. Despite some skepticism from colleagues, he reports that 60-80 percent of human dental pulp cells are stem cells, up markedly from the previous estimate of 1 percent.

“Although nobody reported regeneration of those tissues from dental pulp, I had a hypothesis that dental pulp would be a good source of somatic stem cells,” Dr. Yagaeki wrote in an e-mail. “Of course all people denied my hypothesis. In the meeting of International Association for Dental Research, a chairman of my session called us as stupid.”

After this vindicating discovery, Yagaeki looked to test the impact of halitosis on the development of stem cells into hepatic cells.

After stem cells were harvested from the center of human teeth (don’t worry – the teeth extractions were part of normal dental treatments), the samples were then split into test and control groups. Using a battery of tests, researchers were able to show that a very high percentage of the stem cells incubated in an environment with hydrogen sulphide successfully became hepatic cells.

It was a lucky discovery. Initially, Yagaeki had attempted to learn about negative effects of hydrogen sulphide on the samples before noticing that in small concentrations, the compound had the opposite effect.

Finally, the testing showed high purity in the end result -- fewer cells differentiated into different kinds of cells or remained as stem cells. Pure stem cells greatly reduce the chance of teratomas or cancers in the patient as compared to stem cells originating from bone marrow, making this a promising area for further research.  

“After transplantation into animals or human, those contaminated stem cells or cells differentiating to other tissues may produce teratoma or cancer,” Yagaeki said. “Bone marrow stem cell transplantation is frequently carried out, but the incidence of cancer increases dramatically.”

As it happens, even bad breath might have a therapeutic use. Easy on the Listerine next time. 

More from The Body Odd: 

• Why do we drool in our sleep? 
• Now that really stinks! Scientists blame bug for bad breath
• When your foul smell is all in your head

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Your coffee habit may be helping to protect your brain.

For years we’ve been told that caffeinated coffee was bad for us. It’s unhealthy and addictive, doctors warned. But as vindication for all who stuck by their energizing elixir, a new study shows that guzzling caffeinated coffee may actually be good for our brains. In fact, it may help keep Alzheimer’s at bay.

The study, which was published early online in the Journal of Alzheimer’s Disease, was in mice whose DNA had been tweaked to contain a human Alzheimer’s gene. Just like humans with familial Alzheimer’s, these mice become increasingly forgetful as they age.

Amazingly, the equivalent of four to five cups of caffeinated coffee every few days led to much improved memories in the Alzheimer’s mice, says study co-author Gary Arendash, a scientist at the Florida Alzheimer’s Disease Research Center in Tampa.

Earlier research by Arendash and his colleagues showed that caffeine could at least partially block the production of beta amyloid, the sticky protein that clogs the brains of Alzheimer’s patients. They also found that a substance called granulocyte-colony stimulating factor, or GCSF, sparked the production of new axons, the communication cables that link nerve cells together, as well as new nerve cells themselves.

What’s really interesting is that caffeinated coffee -- but not decaf -- boosted the production of GCSF. 

For the new study, Arendash and his colleagues “treated” healthy mice and Alzheimer’s mice with either caffeinated or decaffeinated coffee. Then the researchers ran a test to see if either beverage led to better memories.

The test they used mimics one that is given to humans to diagnose Alzheimer’s. In that test, people are given a bag of objects to look through (we’ll call that Bag A). And then they’re shown another bag of objects (Bag B). Later on, they’re asked to remember what was in Bag A.

Studies have shown that people with Alzheimer’s have a tough time remembering what was in Bag A because the distraction of looking through the objects from Bag B gets in the way of storing the contents of A in their long term memories. That’s generally not a problem for people with healthy brains.

The two part mouse test involved water mazes. The mice has to find -- and remember -- the location of a submerged platform in a tub of water that is deep enough that they need to swim till they find the platform.

After they find the platform in one tub, they’re moved to another tub where they have to find yet another platform. Mice with Alzheimer’s generally have a tough time remembering the location of the first platform when they’re placed in the original tub. But in Arendash’s study, Alzheimer’s mice that got caffeinated coffee had memories that were just as good as those of normal mice.

Lest you dismiss this study because it’s just in rodents, Arendash says he’s got new data in humans. That data is still being analyzed, he says, but so far it looks like caffeinated coffee has the same impact in people as it does in mice.

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