Professor Leslie Jacobsen, Yale University School of Medicine
One of the most common addictions on Earth is the addiction to cigarettes, so tobacco and nicotine addiction. A very interesting study has been done by Professor Leslie Jacobsen, she's at Yale University School of Medicine, looking at how smoking affects the brains of teenagers.
Chris - Hello Leslie...
Leslie - Hello!
Chris - Thank you for joining us on the Naked Scientists, what have you found?
Leslie - Well we studied 67 teenagers in this group and found that the children or the teenagers who smoked, relative to those who didn't smoke actually had a decline in attention, in particular auditory attention, and at the same time had abnormalities in the structure of their brain that looked like premature developmental changes. The reason why this intrigued us is that, in fact nicotine in tobacco smoke binds to a receptor called the nicotinic acetylcholine receptor that's very important in modulating development in both prenatal and adolescent life.
Chris - So you can actually place the receptor for nicotine, the part of the brain it affects, at the part of the brain you're seeing changes in at this phase in a teenagers development?
Leslie - Right. The receptor is actually very widely present in the brain, it's all over, but we do know from research in rats, in particular by Dr Metherate at the University of California in Irvine, that nicotine can alter the normal development of parts of the brain that support auditory attention. This is very intriguing to us because nicotine exposure during prenatal development leads to a greater risk of impairment in auditory attention and attention deficit hyperactivity disorder. So we actually feel that these findings may show us how this may be happening at least in some children.
Chris - How did you actually make the discovery in the first place?
Leslie - We first recruited teenagers who smoked and those who didn't, and interviewed the mothers of the teenagers as to whether they smoked during the pregnancy and we also obtained birth records to verify the mother's reports. Then we tested them in a special test that looked at auditory and visual attention, and then obtained some MRI scans, which is basically taking a picture, with a very strong magnet, of the brain. We can measure both structure and the maturation of white matter as well as blood flow linked to cognitive work, like paying attention to a task or listening carefully in the presence of distractors.
Chris - And this showed that the children who had either been prenatally, so when their mother was pregnant, exposed to smoking or as teenagers were exposed to smoking, had a greater degree of distractability. It was easier for them to be put off from a task that they were doing when you had some sort of auditory stimulus, some noise or something?
Leslie - Exactly, and the effects were most pronounced when the kids were exposed both prenatally and during adolescence.
Chris - And what about in adults, Leslie?
Leslie - Are you asking whether it reverses during adulthood?
Chris - Well I guess yes, because what we want to know is, a lot of people take up smoking when they're in their teenage years, do they still continue to suffer from these problems into adulthood, or do they get better, or do you not yet know that?
Leslie - We don't specifically know that. It's likely that stopping smoking would improve attention, I think it's worth a try. However what we do know is that acutely when you stop you go through nicotine withdrawal, and that's very hard on attention. So if you already have a deficit in attention and it gets worse during the first few days or weeks of stopping smoking, then I think there's even more pressure to relapse to smoking, if you follow what I'm saying. In other words, this deficit may make it actually harder to quit.
Chris - And you don't think that the people in your study, when they're in the brain scanner, were feeling a bit nicotine deprived and this was putting them off from doing the trial properly, because normally they would have been smoking?
Leslie - We actually studied the smokers, we didn't ask them to stop smoking for this study and they often took a smoke break right before they took a scan. We measured their nicotine plasma concentrations and they were very much in a stable area that was consistent with smoking. They were not in nicotine withdrawal.
Chris - So where are you going to take this next?
Leslie - Well the next question I think we have here is whether we can measure changes early after pre-natal exposure. We're working to develop a study that will recruit infants with and without exposure, look at brain structure using the MRI scanner, which is very safe, and then follow them prospectively. The idea here is to identify what infants are affected and then of course whether we can develop therapies that will improve their attention and reduce their risk of smoking and other problems that come from inattention, like school failure.
Chris - Well let's hope that it isn't permanent, Leslie, thank you very much.
Leslie - My pleasure.
Chris - That's Professor Leslie Jacobsen, she's from Yale University School of Medicine and has found that people who are exposed to nicotine, as their mother smoking for instance when they're in the womb, or as a teenager, can have consequences for the structure of their brain as they get older.
Kat - Scary stuff. And if your New Years resolution was to give up smoking, and it's not too late - it's never too late to give up smoking! If you do want help with that the best thing to do is to go to your GP and they can put you in touch with the NHS stop smoking services - best way to give up.