In a very interesting article published this month (march 2014) published in the prestigeous medical Journal of Craniofacial Surgery , with the title “Lateralized Differences in Olfactory Function and Olfactory Bulb Volume Relate to Nasal Septum Deviation” we can see that up to 72% of patients with left septal deviation have lateralized nasal obstruction on olfactory bulb that leads to HYPOSMIA (partial loss of olfactory function in the obstructed nostril).
In that common cases of LEFT septal deviation with lateralized nasal obstruction, using the so called ”smell test “ someone could be misdiagnosed as having AD or some dementia . while only havING a left septal deviation.

Abstract:

“ One of the most common reasons for partial nasal obstruction is nasal septal deviation .
The effect of a partial lateralized nasal obstruction on olfactory bulb volume remains unclear.
Thus, the aim of this study was to investigate the side differences in olfactory function and obstruction on olfactory bulb in patients with serious nasal septal deviation.
Sixty-five volunteers were included: 22 patients with serious RIGHT obstruction on olfactory bulb and 43 patients with LEFT OBSTRUCTION ON OLFACTORY BULB.
The patients’ mean AGE WAS 22 YEARS OLD.
All participants received volumetric magnetic resonance imaging scans (MRI) of the entire brain and detailed lateralized olfactory tests.
The majority of the patients exhibited an overall decreased olfactory function (as judged for the better nostril: functional ANOSMIA (total loss of olfactory function) in 3% of patients, HYPOSMIA (partial loss of olfactory function in 72% of the patients, NORMOSMIA (normal olfactory function) in 25% of the patients , which seems to be mostly due to the OVERALL SEVERE CHANGES in nasal anatomy.
As expected, olfactory function was significantly lower at the NARROWER SIDE as indicated for odor thresholds, odor discrimination, and odor identification (P ≤ 0.005).
When correlating relative scores and volumes (wider minus narrower side), a significantly positive correlation between the relative measures emerged for OBSTRUCTION ON OLFACTORY BULB volume and odor identification, odor discrimination, and odor thresholds.

OUR STUDY CLEARLY HIGHLIGHTS THAT SEPTAL DEVIATION RESULTS IN DECREASED OLFACTORY FUNCTION AT THE NARROWER SIDE.”
(abstract pasted from the Journal of Craniofacial Surgery-March 2014-Vol. 25 - Issue 2: p 359-362)

Could we please have the citation on this article: names of authors; where published and when? Thank you. I would like to read it for myself.

She is in error when she links the left nostril (left side of the nose) and the left side of the brain. In fact, the left hemisphere manages the right or contralateral side of the body. However, the sense of smell is mediated by one of the 12 cranial nerves, the Olfactory Nerve. The cranial nerves evolved long before the cerebral cortex, which is what pop psychology means when it natters on about an old model of the brain as being divided into "left brain" and "right brain." In fact, the olfactory nerve emerges from the Rhinencephalon or "nose brain", which is shared by snakes, lizards etc. WHY differentiating between responsiveness of left nostril vs. right nostril indicates anything about cognition I don't know. By the way, did they also test for whether their subjects were right handed or left handed? The brains of SOME left handed persons are wired differently than the brains of right handed people.

I had a nasal polyp for a while that made me unable to smell -- even peanut butter -- u WEIRD lack of senastion! ntil the surgeon removed it.

With senses being altered as part of the aging process for many seniors I find this study to be interesting to say the least. I would like to see further research to verify the initial findings. As another person pointed out, smell, hearing, taste all become altered as a person ages. Minimally, seniors would be getting the benefit of proteins but I do not think that the medical community is going to start performing the sniff test as part of their diagnostics for diagnosing Alzheimer's. Just my thoughts: James, RN

I've read that loss of the sense of smell is one of the early signs of Parkinson's Disease. My mom was recently diagnosed with PD at age 88. She hasn't been able to smell anything for at least 10 years.

Does it really matter whether it's peanut butter, or would any strong smell give the same information?

I have not tried the smell test on my Mom, but she use to eat peanut butter daily on a piece of bread and for nearly a year she says she does not like it. She has been diagnosed with Dementia. Just thought this was strange. She won't even eat peanut butter and use to love it.

My Mom saw this on the news and said " I don't have Alzheimer's because I like peanutbutter"! LOL

The point seems to be whether both nostrils function equally, or the left functions less well. This fits with what a neuroligist told me about my husband's recent brain scan. There was a slight shrinkage overall, normal for age 70 -- but it was evenly distributed, whereas in Altzheimer's some parts of the brain shrink more than others.

A note from author Marlis Powers:

"Several people have raised the point that functions on one side of the body are affected by the opposite side of the brain. Here is what I've read on the subject:

'...with Alzheimer's, the left part of the brain is usually affected first. Smell, unlike sight, is ipsilateral. The side of the body sensing the stimulus and the side of the brain processing the information are the same.' (Jennifer Stamps, University of Florida graduate student researcher)."

My husband, who is a medical professional, says that the "crossover" of brain control occurs at the neck. Although the right side of the brain controls the left arm and leg, and vice versa, the left side of the brain does indeed control the left nostril. Although I have my doubts about the validity of this study, the author is correct about which side of the brain controls the left nostril.

I did this with my known dementia 86 year old,
to shake it up a bit, I threw in molasses and maple syrup
and found out she could not smell any of them,
but thought peanut butter and maple syrup smelled sweet and molasses smelled like pepper.

I had her smell with her eyes closed as looking at it would have given her a cue.

I guess that someone have to worry if he/she knew what is a peanut and now it is asking what is that...

If they cant smell with their left nostril doesnt that mean the right side of their brain is affected?

Always interesting to see your remarks and know you too are leery of what those tests suggest as most of us are. May I suggest my favorite snack, Apples with peanut butter? Yum! And I agree right side of brain to the left and left to right.

Everything from the brain is turned around isn't it? Left side controls the right and right the left.

I think she should have written the article after she tested Charlie. Right now, it's of no value whatsoever.

Hmmmmmmmmmmm............well, I guess a lot of us must have dementia then, because I too used one of those cold products that you swab into your nose, and have noticed a real loss in sense of smell. Plus all the senses seem to dull with age in many people. Sense of taste for sure (is that because they can't smell the food as well?), as many people in the nursing home needed more seasonings, etc. or everything tasted bland to them.

Most seniors not only lose their sense of smell but often food doesn't taste as good either, so I kind of wonder about this test.

Psteigman is correct. Left brain, right nostril.

The left nostril is controlled by the right side of the brain.... so.... can you review this?

Interesting! My mother loves peanut butter! My brother(caregiver) does not give it to her often because she makes such a mess- licking fingers, or running them thru her hair, spillage, etc. I say if she likes it, let her have it! Simple pleasure in life that has been taken away by this awful disease.

I share your skepticism. A 2002 study came to this conclusion: "Patients with Lewy bodies were more likely to be anosmic than those with Alzheimer's disease or controls. Patients with Alzheimer's disease were not more likely to be anosmic than controls." http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1737382/

It is well established that many persons with Lewy Body Dementia experience loss of smell. My husband lost his sense of smell, and his LBD diagnosis was confirmed on autopsy. Lots of things can cause loss of the sense of smell.

I'm also skeptical because these were patients diagnosed to be in early stage Alzheimer's. But post-mortem statistics so far show a not-very-impressive accuracy rate of dementia diagnosis. In my small caregiver support group, many caregivers had loved ones who received a series of different diagnoses as they went from one doctor to another. My husband's diagnosis was confirmed post-mortem; another diagnosis in our group was found to be incorrect when the autopsy was done. So how many of the "patients with known Alzheimer's" really had Alzheimer's? Unless there is post-mortem confirmation of diagnosis, this study is merely interesting. I can't imagine it has much diagnostic validity.

I hace noticed quite a few older people no longer can smell and most do not have alzheimers. they also lose their sense of taste. my SIL also took that cold med several yrs ago(before they took it off the market) and she lost all sense of smell. her dr at the time said many used the product and lost their sense of smell.