What if applying perfume or cologne just before going to bed was all it took to prevent dementia, Alzheimer’s or other neurodegenerative diseases?
There is no denying that it sounds promising, and it sounds even better when you realise that, with a few nuances, it’s not so far from being a real possibility.
It has been known for some time that there is a close relationship between smell and memory—just ask Marcel Proust about that—and science has confirmed this. A connection whereby odours facilitate the retrieval of memories. Or, in other words, smells stimulate memory. It also means that loss of olfactory sensitivity and cognitive decline go hand in hand. The former may therefore act as a predictor of the latter, allowing the early detection or diagnosis of neurodegenerative diseases such as dementia or Alzheimer’s disease.
On the other hand, there is a growing body of research showing that environmental enrichment or sensory stimulation, i.e. exposure to different and varied sensory stimuli such as music, sounds, images, tastes, etc., helps to prevent, delay and even reverse this decline. This effect is due to the fact that this type of stimulation promotes neuroplasticity.
The importance of smell
To achieve the best results, olfactory stimulation is particularly important. The explanation of neuroscientists is that odours reach the brain more directly—through the olfactory bulb—than other sensory stimuli, which are first collected in the periphery and then relayed to the brain for processing. This difference that can be likened—with obvious differences—to seeing a live performance versus watching it on television. The experience is always more vivid, intense and memorable in the former case than in the latter, regardless of the definition and capabilities of the screen.
Experimental studies have shown that exposure to a variety of aromas over time increases olfactory sensitivity and, in parallel, improves memory and related cognitive functions, such as verbal fluency, which is highly dependent on the ability to retrieve vocabulary stored in memory. One consequence of this type of stimulation is an increase in the volume and density of the brain’s grey matter: the number of neurons and the connections between them in areas associated with memory and learning. At the same time, it increases the activity of the uncinate fasciculus: a tract or conduit of nerve fibres—a kind of wiring—that connects different regions of the brain with an important role in memory. This occurs in people with dementia or Alzheimer’s disease as well as in healthy adults.
This brings us back to the original question, as a recent study conducted by researchers at the University of California Irvine has found that the diffusion of different fragrances for two hours a night over six months exponentially improved the memory of healthy elderly people. Scores on memory tests improved by up to 226%—and this improvement was also detected through magnetic resonance imaging, which showed an increase in the activity of the uncinate fasciculus. If this conclusion is confirmed, as the research authors suggest, it could become a simple non-invasive technique to strengthen memory and help prevent dementia.
Testing the senses
These encouraging and surprising results suggest a number of experiments to explore the potential of this technique:
The first, of course, would be to replicate the original experiment, albeit for a shorter period of time, taking advantage of the dramatic increase in memory capacity experienced by the study volunteers. This suggests that it is plausible that the effects, although more modest, could manifest themselves in a significantly shorter period of time. So the steps would be:
- First, carry out a test of basic memory and verbal capacity.
- Then try applying a perfume or cologne* every night just before going to bed for 1-2 weeks (preferably with a different scent every night of the week, or at least alternating them).
- Finally, at the end of the treatment, check whether this small effort has been worthwhile by taking the memory and verbal ability test again and comparing the before and after results.
*An alternative to spraying yourself with perfume or cologne is to leave a very fragrant substance on your bedside table, such as herbs or aromatic spices like rosemary, mint, peppermint, parsley, thyme, coriander, etc. (the fragrances used in the experiment were rose, orange, eucalyptus, lemon, mint, rosemary and lavender).
A basic test
To test the effect on memory, the researchers in the above-mentioned study used the Rey Auditory Verbal Learning Test, which in its most basic version consists of the examiner reading a list of 15 words to the subject, who has to try to remember as many of them as possible after 30 minutes (the words are: Drum, Curtain, Bell, Coffee, School, Father, Moon, Garden, Hat, Farmer, Nose, Turkey, Colour, House, River).
For the verbal ability test, the volunteers were given a test similar to a crossword puzzle.
To explore the potential of this technique, a further series of thought experiments are proposed:
- Try watching a film, reading a book or studying a subject (if you are a student or studying for public examinations) after perfuming yourself or lighting a scented candle and try to remember as many details as you can a week later. Do you notice any difference? Do you remember it better than when you do the same exercise under normal conditions?
- Without perfume, do the memory test (ask someone to draw up a list of 15 words and read them to you, or read them to yourself and try to remember as many as you can after half an hour) and do a crossword puzzle. Afterwards (e.g. the next day) repeat the exercise after applying cologne/perfume or after lighting a scented candle in the room. Repeat the exercise again with the scent and also with the scented candle to see if a greater number and variety of simultaneous olfactory stimuli improves performance.
Finally, and following another recently published study confirming that olfactory stimulation with familiar fragrances and odours stimulates the recall of memories and events associated with that smell—again, Proust’s freshly baked madeleines—it is tempting to ask: what if applying a particular perfume while studying and then spraying the same perfume just before taking the exam could improve our ability to remember the subject studied?
If you are studying for an exam, you can try this experiment in the privacy of your own home before going to the exam. And if you’re one of the lucky ones who no longer has to worry about hitting the books, you can do an analogous experiment, but again by watching a film or reading a book:
Comments on this publication