Sniffing Out Alzheimer’s

peanut-butter-memory-400x400A dollop of peanut butter and a ruler might be a way to confirm a diagnosis of early-stage Alzheimer’s disease.

Jennifer Stamps, a graduate student in the McKnight Brain Institute Center for Smell and Taste, came up with the idea of using peanut butter to test for smell sensitivity.  when she was working with Kenneth Heilman MD, a professor of neurology at the University of Florida.

One of the first places in the brain to degenerate in people with Alzheimer’s disease is the front part of the temporal lobe that evolved from the smell system. This portion of the brain is also involved in forming new memories. The ability to smell is associated with the first cranial nerve – the olfactory nerve.

Because peanut butter is a “pure odorant,” it is only detected by the olfactory nerve.

In a small pilot studypatients sat down with a clinician, a tablespoon of peanut butter and a metric ruler.

peanut butter testThe patient closed his or her eyes and mouth and blocked one nostril. The clinician opened the peanut butter container and held the ruler next to the open nostril while the patient breathed normally. The clinician then moved the peanut butter up the ruler one centimeter at a time during the patient’s exhale until the person could detect an odor.

The distance was recorded and the procedure repeated on the other nostril after a 90-second delay.

The clinicians running the test did not know the patients’ diagnoses, which were not usually confirmed until weeks after the initial clinical testing.

Patients in the early stages of Alzheimer’s disease had a dramatic difference in detecting odor between the left and right nostril – their left nostril did not detect the smell until it was an average of 10 centimeters (almost 4 inches) closer to the nose than the right nostril.

This was not the case in patients with other kinds of dementia. These patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one.

Of the 24 patients tested who had mild cognitive impairment, which sometimes signals Alzheimer’s disease and sometimes turns out to be something else, about 10 patients showed a left nostril impairment and 14 patients did not. The researchers said more studies must be conducted to fully understand the implications.

At the moment, we can use this test to confirm diagnosis,” Stamps says. “But we plan to study patients with mild cognitive impairment to see if this test might be used to predict which patients are going to get Alzheimer’s disease.”

Many of the tests used to confirm a diagnosis of Alzheimer’s disease or other dementias can be time-consuming, costly, or invasive.  In contrast, according to the researchers their peanut butter and ruler test could be used by clinics that don’t have access to the personnel or equipment to run other, more elaborate tests required for a specific diagnosis.

peanut-butter-and-jelly-sandwich_0And of course there’s the benefit that you can eat the test afterwards!

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Like this post?  Check back on Monday for more ground breaking Alzheimer’s news.

Sleeping Your Way to Success

As the fall semester winds down at colleges and universities, countless students will doubtless be pulling all-night study sessions to prepare for upcoming exams. Fueled by Red Bull, Monster energy drinks, or sheer fear of failure, last minute cramming will be going on in dorm rooms, libraries around the world.

Ironically, as it turns out, the loss of sleep during these all-nighters could actually work against students performing well.

Dr. Philip Alapat, medical director of the Harris Health Sleep Disorders Center, and assistant professor at Baylor College of Medicine, recommends that students study throughout the semester instead, and get at least 8 hours of sleep the night before exams.

Memory recall and ability to maintain concentration are much improved when an individual is rested,” he says. “By preparing early and being able to better recall what you have studied, your ability to perform well on exams is increased.”

College-aged students ideally should get 8-9 hours of sleep a night. Truth is, most students get much less.

Any prolonged sleep deprivation will affect your mood, energy level and ability to focus, concentrate and learn, which directly affects your academic performance,” Alapat adds.

All-nighters, especially when coupled with caffeinated beverages lead to a risk for developing insomnia and sleep disorders, including apnea, restless legs syndrome, narcolepsy and chronic fatigue syndrome.

Alapat’s recommendations:

  • Get 8-9 hours of sleep nightly (especially before final exams)
  • Try to study during periods of optimal brain function (usually around 6-8 p.m.)
  • Avoid studying in early afternoons, usually the time of least alertness
  •  Don’t overuse caffeinated drinks
  • Recognize that chronic sleep deprivation may contribute to development of long-term diseases like diabetes, high blood pressure and heart disease

Good advice!  Excuse me while I go to bed – I have an Advanced Cardiac Life Support (ACLS) exam in the morning!

He who felt it, probably smelt it

On the other hand, people who can’t feel pain, due to a rare genetic defect, also lack the sense of smell.  At least this seems to be the case according to a new small scale study just published in Nature. The unexpected discovery shows that nerves that detect pain and odors rely on the same protein to transmit information to the brain.

Researchers examined three people with mutations in the SCN9A gene which means they can’t feel pain.  All those studied had suffered multiple broken bones without feeling any pain, and two had gone through childbirth birth painlessly. However they weren’t aware that they also couldn’t smell a thing.

None of the study participants could distinguish balsamic vinegar, orange, mint, coffee or perfume from plain water, even when researchers poured on so much perfume and vinegar that the scents were unbearable to people with a normal sense of smell.

It may not be so strange that none of the people realized that they lacked a sense of smell. “If this was a genetic defect from birth they wouldn’t even know what they were missing,” says Graeme Lowe, a neurophysiologist at the Monell Chemical Senses Center in Philadelphia who was not involved in the study.

As oblivious as the patients were to their smell deficit, the scientists had been equally clueless that smell and pain shared a common communication gateway.

Researchers had previously shown that SCN9A controls pain sensitivity in people. The gene makes a sodium channel that lets sodium pass in through a nerve cell’s membrane when the nerve detects something painful. That flood of sodium sends an electrical signal racing toward the brain.

In the new study, the team discovered that odor-detecting nerve cells have the same sodium channel.

Because the sodium channel is missing in people with SCN9A mutations, the messages sent by pain and odor-sensing nerves never actually make it to the brain.

It was completely surprising that these two sensory systems would use the same sodium channel,” says Frank Zufall, a neurophysiologist at the University of Saarland School of Medicine in Homburg, Germany. “But it’s clearly not needed for all senses.” None of the people with the faulty gene had hearing or vision problems. The researchers next plan to test whether those people have a sense of taste, and whether taste cells also use the sodium channel to communicate.

These findings are particularly interesting given that some drug companies are working on painkilling drugs that block the sodium channel’s activity.  The results of this study suggest that such drugs could have the side effect of eliminating smell, and could also compromise people’s ability to taste.

Imagine going though life never knowing the smell of newly baked bread, or the delights of freshly ground coffee?  Now that would be painful!