Quitting smoking is easy. I've done it a thousand times.

by Cristina Menchaca (2007-49018)

Smoking is one of those things people tell you not to get into because once you're in, it's hard to get out. And well, it's bad for your health. Smoking has been a huge public health problem all over the world, and it leads to many deaths- even if you're not the smoker (secondhand smoke). Everyone knows that smoking has negative consequences. We can all say it along with the advertisers: 'government warning, cigarette smoking is dangerous to your health'. Yet of the very few smokers who try to quit on their own, they can abstain only for so long. Why is it so hard to remain nicotine-free? There are two main factors for failing to abstain from smoking: one, people go back to smoking to relieve the withdrawal symptoms they experience from not having nicotine anymore, and two, people go back to smoking after they're exposed to smoking-related cues, which of course, elicit craving responses. This quote might looks at how strong the craving is: I read that smoking is bad for your health. This upset me so much that I decided never to read again.

One year ago, a group of researchers looked at how the brain looked when people abstaining from smoking saw pictures related to smoking. What did they find out? Something that goes like this: whenever I think about quitting smoking, I need a cigarette to think. In other words, the brain's reactivity to smoking-related cues could be a reason why it's hard to quit smoking, and, reactivity in the brain could change depending on how long it has been since a person has stopped smoking.

The technique used to look at brain reactivity in response to the stimuli was the fMRI (ferro-magnetic resonance imaging). Two types of stimuli were shown to the participants: either smoking-related images (people smoking, hands holding cigarettes, or just cigarettes) or neutral images (faces, hands, as long as they had no cues for smoking). The participants in the study were not just any kind of smoker but were smokers classified as nicotine-dependent, and this was based on the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders). There were 13 participants, all of whom were females (with a mean age of 43) and who happened to be taking part in a clinical trial on smoking cessation. Their consent and the consent of the hospital was taken, of course. Brain reactivity to the stimuli were measured twice: once before the attempt to stop smoking (prequit), and the second time after extended smoking abstinence (about 52 days). During the cessation period, participants were aided by nicotine replacement therapy, or NRT, to help them in their abstinence from smoking. Amount of NRT administered was also reduced in time.

The stimuli were shown to the participants as colored pictures. Aside from the smoking-related and neutral pictures, target images of animals were also used to ensure that participants were paying attention in the study (participants had to press a button upon seeing the picture of an animal). A total of 42 smoking, 40 neutral, and 8 target pictures were shown to each participant in a pseudo-random order. Each picture was shown for 4 seconds, and there was a break of 14 seconds between pictures. To avoid practice effect, different pictures were used the second time of testing (extended smoking abstinence of about 52 days). Not only were the reactivities between neutral stimuli and smoking-related stimuli used, but a within-subjects design was also used to compare reactivities before and during extended smoking abstinence.

It was found that there was more brain activity for cigarette-related stimuli than neutral stimuli. It was also found that during the period of extended smoking abstinence, reactivity of the brain was in specific areas of the precaudate nucleus, the prefrontal, primary somatosensory, temporal, parietal, anterior cingulate, and posterior cingulate cortexes. Too much neuro terms? Basically, the mentioned areas are those that have to do with attention, somatosensory processing, motor planning, and conditioned cue responding. The regions involved in the fMRI scans were those that have to do with reward, craving, emotional processing, memory, visual attention, and impulsivity. The fact that the previously mentioned parts of the brain show more activity after a long period of cessation (about 52 days) means that even after such time, reactivity to smoking-related stimuli still persists. Not only does reactivity persist, but in some parts of the brain, reactivity was shown to be even more intense during the extended cessation period. The caudate nucleus and other areas involved in learning, action planning, and motor behavior, are examples. This could probably be the reason on why people are vulnerable to persistent relapse even if it has been days since one's last cigarette. The insula, which has do do with maintenance of behaviors, craving, and exposure to cues, was also active during both scans (prequit and extended abstinence).

For more specific ares of the brain and what they correspond to, read this (if not, skip to the next paragraph!):

The first and second fMRI results (prequit and extended smoking abstinence) showed that there was a significantly greater activity in the brain for smoking-related images than for neutral ones. Areas of the brain that showed activity in both scans were the frontal, anterior cingulate, posterior cingulate, temporal, parietal, and occipital areas. Across time, the different areas of the brain that showed activity were the frontal, anterior cingulate, posterior cingulate, temporal, and parietal areas (cortically) and the cortical nucleus (subcortically). Such regions have been shown to be active with smoking-related and and drug-related cues. The first scan revealed an increase in regions involved in emotional processing (frontal and anterior cingulate cortexes), visiospatial processing areas, and temporal areas correlated to smoking cues. The second scan showed activity in the prefrontal, anterior cingulate, posterior cingulate, temporal, and parietal areas, and the caudate nucleus. Such areas have to do with action planning, habit learning, and craving. Specifically, the anterior cingulate cortex is an area that deals with cue-induced motor responses, the posterior cingulate cortex is an area that gives attention to reward-associated stimuli, and the prefrontal, parietal, and somatosensory cortexes are involved in imagined and executed movement, which can promote the reinitiating of smoking.

I'm honestly very impressed with this study and I'm not saying that just because I'm writing about it. I liked that the researchers thought about almost every single detail in their study to make sure that they get results as accurate as they can. They chose participants who all wanted to stop smoking, and they did not include women with an unstable mental illness, a lifetime diagnosis of an organic mental disorder (schizophrenic, bipolar, etc.), a history of alcohol abuse, and women who were unresponsive to an adequate course of NRT, depressed (the Hamilton Rating Scale for Depression, administered again after the first scan), or pregnant (urine test). Vital signs were also checked for normality, and even recent smoking and alcohol use were tested, especially before scans. Also, aside from using the DSM-IV to get nicotine-dependent participants, another test was used (the Fagerstrom test for nicotine dependence). Even hormone levels were taken into consideration: the second scans were taken at around the same point in the participant's menstrual cycle for the first scan. I also liked that NRT was very individualistic so that abstinence could be maximized: each participant was given a specific dose depending on her highest and lowest tolerable doses that effectively blunt withdrawal symptoms. I liked that the use of target images were to ensure that the participants were taking the study seriously, and that the use of neutral images was to ensure that change of brain activity was not an effect of time (or the state of smoking) only. And as a whole, I liked that this study was a spin-off of a previous study that examined fMRI activity but only after 24 hours of cessation. The results were the same as this study (showing support for the incentive-sensitization theory, where the perceived reward value of a drug-associated cue increases during abstinence). It is important to look at brain activity more than 24 hours after cessation if one wants to know whether enhanced reactivity contributes to relapse, which occurs after one has abstained after quite some time. I also liked that the researchers had a defense as to why they had no placebo (in place of NRT), and that it is because the increased brain activity could not have been a result of NRT. If it was, it would have shown clinically, based on NRT users. They also explained that although they did not get participants' subjective ratings on cravings, suggestions are that such answers will minimally inform fMRI data anyway. Very well-thought out indeed!

How does this study...

relate to my current topic in the course of perception? Well, we've been talking about the physiology of perception. Although this study did not mention steps from a stimulus to the brain and from the brain outwards, we know that the stimuli used (neutral images and cigarette-related images) are attendedto by sensory receptors (our eyes), and the sensation is transduced through neural communications into electrical energy. The message is sent to the brain, which in this study, are the different parts that react to the stimuli, that in turn, helps us experience the stimulus, give it meaning, and act on it. From the various parts of the brain, messages are sent to different parts of the body. This is what makes quitting smoking hard. The parts of the brain that are 'activated' are those that have to do with craving, impulsivity, reward, etc. The fact that the different parts of the brain and different parts of the body are stimulated means that the stimulus was strong enough for action potential to occur and send the messages from neuron to neuron, from the optic nerve, to various parts of the brain, to various parts of the body. This whole study shows how the perception of a visual stimulus, such as pictures, causes abstaining smokers to be more likely to relapse. It's because of the signals being sent from neuron to neuron, first hitting the eyes, then getting passed on to the brain, then from there, to different parts of the body as a result of the brainareas that were activated.

So after praising the study, how else could it be improved? One way would be to increase the sample size. Although it's good that the participants were carefully chosen, the researchers were left with 13 participants, not a big enough number to make firm establishments and generalize results. At the same time, participants were all females, and the researchers themselves said that men should also be considered, to see if sex has different implications. It would also be recommendable to make use of participants who are from different areas of the world (or of different cultures), if, as in the case of sex, culture would have different implications. According to the study, brain reactivity to such stimuli for people during smoking is not known, neither after extended periods using NRT (longer than the time in this particular study). Having such information would be good so that parts of the brain involved in relapse vulnerability can be known, and perhaps from such data, medicines for abstinence could be made. Additionally, NRT is known to be only effective for short-term withdrawal symptoms, which suggests that reactivity persists and results in craving or relapse. An extended scan to the point of very reduced (or even none of) NRT would be highly useful in figuring out the physiology behind cravings or relapse during abstinence. Finally, it might be interesting to make use of actual stimuli, not just pictures. If the stimuli used were only images and they already created such activity in the brain, what more real and tangible stimuli? It is no wonder then that people addicted to smoking have a hard time stopping. In fact, some of the participants had slips (smoking part of a cigarette once during the period of cessation), yet they were not excluded from the data because slipping is considered part of going through the NRT experience. And if researchers are interested, they may want to look into how depression comes into the picture. After the second scan, participants showed a higher level of depression, even if they were still in the normal range. Was this a withdrawal symptom? Was it because the body could not satisfy the crave its brain was acknowledging?

So many questions that spring from this study, but it still gave answers on what really is happening behind the scenes, physiologically speaking. What's my moral of the story? Well I'm not going to be naive and tell people not to smoke, because it's really not in my hands. Practically speaking, I'd say to make sure you don't get into the habit of it, or else sooner or later, you'll have the hardest time quitting. The brain can attest to that. And if you do get to that point, you'll probably end up saying, 'I'd stop smoking but nobody likes a quitter'.

Source:

James, A., Frederick, B., Merlo-Pich, E., Renshaw, P., Evins, A. E., Fava, M., et al. (2009). Brain fMRI Reactivity to Smoking-Related Images Before and During Extended Smoking Abstinence.Experimental and Clinical Psychopharmacology, 17(6), 365-373.