Vaping inflames the brain

Rates of eCigarette and vaping product consumption have risen dramatically in recent years. In the UK over just the 5 year period from 2012 to 2017 it climbed by several hundred percent. Many users are former smokers who regard vaping as a healthier option and have switched for that reason. But there’s also a - for the moment small but - growing cohort of “never smokers” who vape because it’s perceived to be low risk. Could it be though that, in the same way that it took decades of following up smoking doctors before Richard Doll could categorically say that smoking causes health harms, vaping - being a relatively new phenomenon - just doesn’t have the data yet for us to know what the health risks are? This is very much the view of UCSD’s Laura Crotty-Alexander…

Laura - In terms of whether the e-cigarette aerosol mixture is safer than conventional tobacco smoke, it looks like it is going to have fewer health effects, but it will have its own set of health effects.

Chris - Which could be different and remote and, in fact, manifest in a different part of the body, presumably, if they're different chemicals than what's in cigarettes?

Laura - Absolutely. Cigarette smoke contains about 7,000 chemicals, and that use of cigarettes leads to damage across the body - everywhere from your lips, where it first makes contact, all the way down to the GI tract and out to the skin and to the brain. And what we sought to find was whether e-cigarette aerosols could also impact all these different organs across the body.

Chris - How did you do it?

Laura - We used a mouse model. So we have this special setup where we take the mice and we put them in a little pie-shaped wedge container where they can move around. And then we use e-cigarettes that we have bought on regular websites and we give them a puff of e-cigarette aerosol and then regular air. And we have them breathe that in for 30 minutes, three times a day.

Chris - And is the mouse dose equivalent to what a human consuming these products would get? Or are the mice getting a much bigger impact and a bigger dose? Because obviously a human breath would be massive for a mouse...

Laura - We do try our best to design these mouse models to mimic human use, which is why we expose the mice multiple times a day, because a lot of humans use e-cigarettes throughout the day. And when we take one puff that's more human-sized, we actually put it into a large chamber where it diffuses. So 16 mice are breathing in that aerosol.

Chris - And how do you then marry up what that intake is doing in different parts of the body?

Laura - We actually harvest the mice and then we take all the different body parts. And we look at them using special tools that look at gene expression or levels of protein. And we actually even look at organ function. And so we use these different measures to try and determine whether inhaling these e-cigarette aerosols over months leads to changes in these organs.

Chris - And what crops up when you do this? Do you see systemic effects?

Laura - Yes. So I was very surprised that we found profound changes in the brain in particular of these mice that inhaled JUUL mint and JUUL mango, which are two flavours that were very popular at the time we started this study. And both of those aerosols led to inflammation in the brain, which is shocking because the brain is a protected compartment. So it was very worrisome that inhaling the e-cigarette aerosols for just a month led to very impressive levels of inflammation in a part of the brain that controls mood and behaviour and memory.

Chris - Are you saying that it's specifically the flavours that are doing that? So this is an effect beyond the addictive qualities of the nicotine and so on?

Laura - In the brain, the fact that we saw similar changes in both flavours indicated more that it was the nicotine and the other substances at the core of these e-liquids that were driving the changes. But, for example, in the heart, we found that the mint flavour really changed and drove inflammation, whereas the mango flavour did not. And so that comparison helped us to understand that maybe the heart effects are maybe particularly driven by the mint flavour and not the nicotine and other components.

Chris - We'll come on in a second to what the impact of that might be, but just considering for a minute the fact you've got this effect, how does it compare in scale with if the mice were just (if mice could) smoking normal cigarettes?

Laura - If I were to look back at the historic data, I would say that the neurologic effects are of a scale that appears to be either equal to, or greater than, what is seen in conventional tobacco, and that the effects are different.

Chris - We believe that chronic inflammation might be linked to at least the progression, if not in some cases the cause, of certain neurodegenerative conditions and probably also degeneration in other organs. So do you think then that this is indicative of the fact that people doing this could be speeding up the ageing process of their brain? They're effectively bringing forward the age at which they may well succumb to degenerative conditions of the nervous system?

Laura - I absolutely agree that that is a concern. And, in addition, the changes in these parts of the brain suggest that people who are using e-cigarettes may have more anxiety and depression and might have sort of permanent changes to their behaviour patterns.