DESLEY BLANCH : What is it about the scent of freshly cut grass that makes you feel good? Why does that distinct smell seem to leave so many people with a sense of calmness? After more than six years of investigation, Queensland neuroscientist, Dr Nick Lavidis believes he has found the answer. His research indicates that the chemicals and odours released by plants when they are crushed, directly affect how our brain manages stress, as he explains.
DR NICK LAVIDIS : It's actually relieving the stress by acting directly on an area of the brain which is involved with emotions, that is the limbic system. The limbic system is involved when you're stressed--activating what is the flight-or-fight response through what is referred to as the sympathetic nervous system. It increases your heart rate, raises your blood pressure and gets you ready to survive a threatening situation. And so these cut grass smells seem to regulate that free-flight kind of response and moderate it so that you are not so stressed.
DESLEY BLANCH : Let's talk a little bit about what prolonged stress does induce in our bodies. What happens, what are the harmful impacts?
DR NICK LAVIDIS : Well, acute stress itself is not a bad thing. It improves your performance and increases memory and so on so it stimulates the brain and causes changes to happen so that you can survive a threatening situation. However, in our daily lives, we are faced with continuous stress and these stress hormones start to build up in our body and they start to over-stimulate, for example, the brain.
This is what we found in our latest work that over-stimulation of the brain results in a number of things. One of the most important things is that it causes a part of the brain which is called the hippocampus involved with memory--laying down of memory--to be over activated and to be eventually damaged by this over-excitation, resulting in memory loss.
DESLEY BLANCH : Okay, well it seems that your interest in the subject was peaked more than 20 years ago, and this was after an unforgettable trip to Yosemite National Park in the United States when your three days in the park felt more like a three month holiday. That sounds rather blissful, but couldn't that be just that you were away from the daily grind of things?
DR NICK LAVIDIS : Certainly, association in humans is a very important factor. An association between a relaxing holiday and a particular smell; when you smell that particular smell again when you are at work and so on can cause relaxation. This is why we conducted most of our experiments to begin with, with animals, which are not linked to easily associate a particular smell with a holiday.
And what we found is that these animals under stress were showing these recovery signs when they were smelling these green aromas that were coming from the plants that we were testing and so on. So yes, association plays an important role in humans and that's why sometimes it's important to do the animal experiments and then to conduct very careful experiments which we are doing at the moment, with humans, so we're doing some psychological trials with these chemicals to now carefully analyse how effective they are on humans. The first signs are that they are very effective.
DESLEY BLANCH : When you were studying the long term effect of intermittent chronic stress in rats and in mice, you learned that the hippocampus became smaller. Why was that happening? What results when the hippocampus becomes smaller?
DR NICK LAVIDIS : What I think is happening is the nerve cells within the hippocampus are pulling back their connections or reducing their connections so that they can reduce the amount of stimulation that is going on and survive this onslaught of excitation.
While that happens, the nerve connections are reducing in number and so you are decreasing the effectiveness of transmission from one nerve to another and therefore memory loss. With young people, these sorts of changes can be easily fixed up with time if you remove the stressor. The older you get though, if you remove the stressor of some of these changes become more permanent and therefore you're stuck with memory loss.
DESLEY BLANCH : And Nick, by smelling freshly cut grass, you believe that can prevent that loss of cells, why?
DR NICK LAVIDIS : We've seen it in the experiments that we have done. It's basically the act of reducing the stress, which is preventing the over-excitation of the hippocampus and allowing the neurons to survive. One interesting thing that we checked is - what happens to the acute stress. That is the immediate stress that we feel when we are threatened, that is not affected at all by the plants.
What they seem to do is allow you to recover after that initial excitation that's caused by the stressor for you survive. You recover from that fairly quickly, much faster than you would if you weren't smelling the plants. So you feel the stress, you respond to the stress, the threatening situation, but you recover after the threatening situation much faster.
DESLEY BLANCH : So do you yet understand why stress is dampened by smelling certain odours and it is not just a case of recognising an odour and the fond memories attached to it?
DR NICK LAVIDIS : There's been a few studies that have shown that there is a direct connection between the olfactory system--the smell part, the sense and a structure called the amygdala which is the structure that activates the fear or flight response. So there is a direct connection into that free-flight kind of response.
So there is that olfactory connection which exists in all warm blooded animals. Most likely it is there as an incentive for animals to move towards in the case of these green smells, towards an area where there is plenty of rain, lots of food in terms of grasses and so on and a sense of comfort when you move into that area. So there is an incentive to activate the emotional part of the brain so that you instinctively move towards this comfort zone.
DESLEY BLANCH : Well, you and your team have identified a number of chemicals found in freshly cut grass and you've bottled them and you've turned them into a fragrance. So how is your fragrance to be used?
DR NICK LAVIDIS : There's many different ways that it can be used initially. A company is marketing it now in the form of a spray that you spray into a room, an average size room--two or three sprays would probably last about six hours easily.
Another way is by massage oil, a massage with that fragrance is fairly relaxing. Other ways that have been thought of is to put it in for example, paints to put it in household products like cleaning products and so on so that the house smells of this cut grass aroma or forest like aroma, personal care products like soaps and shampoos.
DESLEY BLANCH : But it's also well established that physical exercise improves your mood by stimulating various brain chemicals and physical exercise combats chronic diseases and it boosts your energy levels and promotes better sleep. So why not just go for a run, rather than turn to a can for a dose of happiness and well-being?
DR NICK LAVIDIS : Well, the simple answer to that is yes, you should go especially on the weekend, go for a run, go out there and mow your lawn, and go for a bushwalk or walk through the forest and receive all these natural products from nature.
The only reason that this product has been made is because I found that when I am sitting in my office and everyone else that sits in an office or a workplace or are home doing chores and various other things, that time when you are certainly stressed, it's at that time when you actually need these smells and you cannot go out into the forest and do your work and so on, and so spraying your office as I do quite often and my students do with their lab--with that spray makes them feel relaxed and also they feel like they are working in the forest.
DESLEY BLANCH : And have you sprayed it today as your in our studio in Brisbane?
DR NICK LAVIDIS : Yes, I sprayed it on my shirt as I was walking to catch the taxi, to get rid of some of the anxiety that one feels when they are going to speak in public.
DESLEY BLANCH : And I have to ask you, is it working?
DR NICK LAVIDIS : Yes it is. I feel a little bit more comfortable than I was before I sprayed it.
DESLEY BLANCH : So have you done official human trials with your fragrance?
DR NICK LAVIDIS : We're doing at the moment official human trials with the psychology department. They should be coming out in the next one to one and a half years. We'll have preliminary data within a few months.
DESLEY BLANCH : And what's next for this research then?
DR NICK LAVIDIS : The amygdala which is the free-flight type response area of the brain is showing very interesting indications, that is it is well known that when you are chronically stressed, what happens is that instead of those nerve cells shrivelling up, that happens in the hippocampus.
What happens there is that they increase in size and the affecting lines of communication with nerve cells in that free flight type of structure increases, so your fear response is heightened and you suffer things like post traumatic stress disorder and flashbacks. So what we're doing is we're looking at whether these plant chemicals that we've isolated can inhibit this increase in transmission that occurs across these nerve cells and therefore reduce the flashbacks and post traumatic stress disorder. That's an area that is very fresh and we're still working on them.
And very importantly, another area that we're looking at is whether by reducing stress we can reduce the suppression that occurs in the immune system. When you are stressed, your immune system is suppressed, when you're under stress, you can more easily catch colds, flu and various other infections. We're checking to see whether these chemicals that we've derived can prevent that from happening and therefore improve your immune system.
DESLEY BLANCH : Nick Lavidis and his team from the University of Queensland's School of Biomedical Sciences are also checking out possible medicinal benefits of lavender and the American bay leaf.
Dr Nick Lavidis, Senior Lecturer
School of Biomedical Sciences
The University of Queensland
St Lucia Campus, Brisbane, QLD 4072