Smoking kills. Everyone knows that. The message is reinforced by health warnings on packets, government campaigns and common sense. Smoking messes with your body in so many ways. However, when it comes to a smoker's mental health, numerous studies have shown tobacco smoke to actually have positive effects.¹

Smoking makes me feel good!

"Smoking helps me relax", "It helps me concentrate", "smoking feels good"... Statements like these by smokers are common, but are usually dismissed as tricks of nicotine addiction. It's not actually making you feel better, they say, it's the nicotine withdrawal symptoms that makes you feel worse. While there is some truth in this assertion, the evidence points overwhelmingly to the fact that in many cases, nicotine can improve mental state. These cases are usually where the smoker also suffers from mental health problems.

While anti-smoking campaigns have generally proven effective, with rates of smoking in developed countries dramatically lower than they were a generation ago, the exception to this trend is among sufferers of mental illness. Rates of smoking among these groups are significantly higher than in the population as a whole. Among patients with schizophrenia, studies have shown smoking rates between 74² and 88%³, compared to a figure in the population as a whole of around 20%. Among patients with depression, a 56% rate has been shown in one UK study⁴. There is also evidence that depressive smokers find it much harder to quit⁵. Of course, a correlation like this in no way shows the reasons behind these figures. Some have postulated that smoking causes depression, though little evidence has been found to support this. Some evidence has been found to show that a tendency towards nicotine addiction and to depression may have shared genetic factors. However, the bulk of the evidence seems towards the use of nicotine as a form of self-medication⁶, and a suprisingly effective one at that.

Why does smoking help?

When you smoke, nicotine is absorbed by the lungs, enters the bloodstream and makes its way towards the brain. There it binds to receptors for dopamine ⁷, the brain's reward chemical. This accounts for the feeling of well-being experienced when smoking and is the basis of most addictive substances' appeal⁸. Among people with depression, dopamine levels are often unusually low, so this is counteracted by the spike.

However, this short-lived effect is only part of smoking's appeal for the depressed or otherwise mentally ill person. Several studies have also shown that tobacco smoke acts as a monoamine oxidase inhibitor (MAOI). ^9,10,11 Monoamine oxidase is another brain chemical that is involved in the breakdown of dopamine. The studies found that levels of MAO were significantly lower in smokers than among non-smokers. This is interesting for several reasons. MAOIs are often used as anti-depressants, but have also been shown to help in the treatment of Parkinson's disease¹². This may explain findings showing increased depression among people trying to give up smoking¹³, but also, controversially, the lower rates of Parkinson's found among smokers. When someone stops smoking, MAO levels gradually return to normal. This is likely to cause a reduction in the anti-depressant effects felt, and so the depression returns. Some studies have even shown that starting smoking can have beneficial effects for depressed non-smokers¹⁴.

Furthermore, dopamine is known to play a significant but unclear role in schizophrenia⁸. This is an area where more study is needed, but it may eventually offer some explanation for the dramatically high levels of smoking among schizophrenic people.

So should I start smoking?

Of course not, and if you already smoke, you should quit. Smoking kills. However, mental illness also kills. In fact it is one of the developed world's biggest killers. So if smoking really does help sufferers, as these studies appear to show, maybe there can be a case made. This is a controversial subject and it is most likely that smoking's many negative effects outweigh these benefits, but it is interesting to note that smoking does have some health benefits. More research is needed, as many of the causes and effects are still barely understood, but in the meantime it is helpful to know some of the reasons why people smoke and why it is so hard to give up. I also plan to use it as an excuse for not quitting, because I am weak.

This writeup was inspired by an article¹ I read today, along with my own failure to give up smoking. Much of the material was found with the help of material¹⁵ on the website of ASH, a UK anti-smoking research group. Ironic.

1. James "Why I'm still dying for a cigarette" The Observer 29/12/2002 http://www.observer.co.uk/focus/story/0,6903,866130,00.html
2. Meltzer H, Gill B, Petticrew M et al. "Economic activity and social functioning of residents with psychiatric disorders" (OPCS Surveys of Psychiatric Morbidity in Great Britain Report 6). 1996 http://www.doh.gov.uk/pub/docs/doh/newsurvey4.pdf
3. Lohr & Flynn, "Smoking and Schizophrenia" Schizophrenia Res; 8:93-102; 1992
4. Meltzer H, Gill B. Petticrew M et al. "Economic activity and social functioning of adults with psychiatric disorders" (OPCS Surveys of Psychiatric Morbidity in Great Britain Report 3). 1995 http://www.doh.gov.uk/pub/docs/doh/newsurvey4.pdf
5. Glassman AH, Stetner F, Walsh BT et al. "Heavy smokers, smoking cessation, and clonidine. Results of a double-blind randomized trial." JAMA; 1988; 259: 2363-6 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3367452&dopt=Abstract
6. Lerman C, Caporaso N, Main D, Audrain J, Boyd NR "Depression and Self-Medication with Nicotine: The Modifying Influence of the Dopamine D4 Receptor Gene" Health Psychology; 17: 56-62.
7. Voryxnyx "Nicotine" everything2 writeup; 2002
8. enth "dopamine" everything2 writeup; 2002
9. Fowler JS, Volkow ND, Wang GJ, Pappas N, Logan J, MacGregor R, Alexoff D, Shea C, Schlyer D, Wolf AP, Warner D, Zezulkova I, Cilento R "Inhibition of monoamine oxidase B in the brains of smokers" Brookhaven National Laboratory, Upton, New York 11973, USA. Nature 1996 Feb 22; 379(6567):733-6 http://www.biopsychiatry.com/smokemao.htm
10. Berlin I, Spreux-Varoquaux O, Said S, Launay JM "Effects of past history of major depression on smoking characteristics, monoamine oxidase-A and -B activities and withdrawal symptoms in dependent smoker" Department of Clinical Pharmacology, Hopital Pitie-Salpetriere, Paris, France. Drug Alcohol Depend 1997 Apr 14; 45(1-2):31-7 http://www.biopsychiatry.com/smoking.htm
11. Fowler JS, Volkow ND, Wang GJ, Pappas N, Logan J, MacGregor R, Alexoff D, Wolf AP, Warner D, Cilento R, Zezulkova I "Neuropharmacological actions of cigarette smoke: brain monoamine oxidase B (MAO B) inhibition" Department of Chemistry and Medicine, Brookhaven National Laboratory, Upton, NY 11973, USA. J Addict Dis 1998; 17(1):23-34 http://www.biopsychiatry.com/smokmaob.htm
12. Gorell JM, Rybicki BA, Johnson CC, et al., "Smoking and Parkinson's disease. A dose-response relationship." Neurology, 38, pp. 1558-1561, 1988
13. Niaura R, Britt DM, Shadel WG et al. "Symptoms of depression and survival experience among three samples of smokers trying to quit." Psychology of Addictive Behaviours; 2001; 15: 13-17. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11255933&dopt=Abstract
14. Malpass D. "Smoking and mental health seminar." November, 2001. Presentation.
15. McNeill "Smoking and mental health - a review of the literature" St George's Hospital Medical School London, Action on Smoking and Health. http://www.ash.org.uk/html/policy/menlitrev.html

When you inhale the smoke from a tobacco product, such as a cigarette, you are self-medicating your body with a large number of chemicals, the most well known of which is nicotine. Manufacturers also tend to 'bulk out' their products with a variety of additives to maintain the taste and consistency of their cigarettes. Looking at this list of additives is an exercise similar to watching cheap sausages being made. So while the title of this write up is 'smoking is good for your health', a more accurate one might also be 'nicotine gum is good for your health'. Or not. It may well not be the nicotine that is exerting the beneficial effect in some of what I am about to say; unsurprisingly, not much research has been directed specifically into the benefits of smoking. However, I'll be very surprised if turns out it's the formaldehyde that's causing the decreased rates of Parkinson's disease amongst smokers.

We all know (or should know anyway) that smoking cigarettes and other tobacco products is exceedingly bad for your health. I have seen people die from diseases that are directly attributable to their having smoked twenty a day for forty years. Most of them weren't, as deaths go, that nice. I didn't enjoy watching them, and I know sure as hell that their families didn't either. Don't smoke kids; it's not cool and it won't get you laid.

Nevertheless, despite what the anti-smoking lobby would have us believe, it isn't all bad. Smoking has been shown to have a positive health benefit for several disease processes. While I would never advise anyone to start up smoking for these reasons, or in fact put off quitting either, I am a stickler for knowing all the sides of the story before making a decision on a matter. I would like to stress that for all the disorders that I am about to go through, smoking has been proved to have a beneficial effect that is not due to the fact that smoking kills people at a younger age before many of these disease processes develop, meaning there are less smokers around to die of anything else. I have used reputable studies that have compared smoking and non-smoking populations. Trust me, smoking being good for you is not something that anyone apart from the tobacco barons would want you to think, and the papers that I have referenced went through a rigorous vetting procedure before they were allowed to be published. Knowing about these positive benefits opens up interesting avenues of research in our fight against disease, and it is important that these are not ignored. Unfortunately, people can be so polarised with the issue of smoking that they will deny that smoking is anything but an evil habit that should be stamped out. I'm not arguing with them, but I do believe that if it offers us an advantage, any advantage, we should use it.

Parkinson's disease

Parkinson's disease is a progressive neurodegenerative disease affecting the dopaminergic neurones found in the basal ganglia of the brain. It leads to tremor, muscle rigidity and slowness of movement. Several studies, prospective and case-controlled, have concluded that there is a lower incidence of Parkinson's in smokers compared to non-smokers (Elan et al, 2003, Gorell et al, 1999, Grandinetti et al, 1994). In 2003, Elan et al completed a study of an elderly population that concluded that 45.1% of the non-smoking population exhibited parkinsonian-like symptoms in comparison to 32.5% of smokers. These finding have been replicated many times.

There are currently several theories as to why this might be. The first may be behavioural. It is hypothesised, though unlikely, that those with a genetic predisposition to developing Parkinson's are more likely to shun cigarette smoking. Another is that nicotine increases the expression of neurotrophic factors that are known to promote survival of dopaminergic neurons. This has been backed up with evidence from animal studies into Parkinson's (Maggio et al, 1998). A third is that it is not just nicotine that is exerting an effect. As previously mentioned, there are numerous chemicals in tobacco smoke, and these may be, for example, causing a reduction in the activity of monoamine oxidase A and B. This might in turn protect against neuronal damage by inhibiting the enzymatic oxidation of dopamine (Castagnoli, 2001). There is currently a large amount of research being done in this field, as Parkinson's is a disease that affects many in old age. As yet there is no satisfactory treatment, and this can be especially disheartening for those who may be affected at a young age.

But I don't smoke! How can I help myself?

Caffeine has also been shown to have a protective effect against Parkinson's. Whilst this protective effect has not been shown to be as strong as with smoking, it might still be an idea to start knocking back a bit more tea and coffee in the day.

Endometrial Carcinoma (and other *ahem* female troubles)

Adenocarcinoma of the endometrium is the most commonly occurring female genital tract cancer in developed countries. It occurs mainly in the reproductive and menopausal age groups, and has a high mortality rate. Again, there have been many studies that have linked smoking with a lower incidence of endometrial carcinoma (Levi et al, 1987). It is assumed that this effect is due to smoking having an antioestrogen effect. This effect is mediated in several ways, including the induction of liver enzymes, which lowers the amount of circulating oestrogens in the body. Female smokers also tend to experience menopause earlier than non-smokers, and are less likely to be obese (Parazzini, 1995).

This induced antioestrogen effect also means that rates of uterine fibroids and endometriosis are lower amongst smokers. It also explains why women who smoke during their pregnancy have a lower incidence of pregnancy-induced nausea; morning sickness is attributed to the high levels of circulating oestrogen that occurs in pregnancy. I'd like to stress though that it is very important that you DO NOT SMOKE DURING PREGNANCY. Sorry to shout.

But I don't smoke! How can I help myself?

Well, if you're male, you have nothing to worry about. Females can benefit by having a large number of babies, maintaining a healthy weight, experiencing an early menopause, taking the oral contraceptive pill and keeping their cholesterol down. I know that having a large number of babies and taking the oral contraceptive pill are quite hard to do at the same time, but there's nothing to stop you trying.

Obesity

Obesity is the accumulation of body fat such that the patient starts to experience negative health issues because of this accumulation. It is medically defined as a BMI greater than 30, and is now the biggest medical problem faced by the developed world. There are a few who can claim genetics or medication to be the cause of this, but for the most part, it is a simple result of too many calories consumed and not enough expended.

However, it has long been known that those who smoke tend to be slimmer. This is probably a result of several mechanisms. One is that smoking has been found to increase circulating levels of leptin, a hormone that regulates the body's fat stores (Nicklas et al, 1999). Smoking also causes an increase in the levels of circulating catecholamines via the sympathetic nervous system, which causes the body to burn off up to 10% more energy than if the person didn't smoke (Hofstetter, 1986). Another study has found that nicotine acts to increase dopamine and serotonin levels in parts of the hypothalamus, which results in reduced appetite (Miyata, 1999).

But I don't smoke! How can I help myself?

Sorry to be the bearer of bad news on this one, but eat less and exercise more. One piece of advice that I will give is that commercial diets don't work that well. It's true. There's published papers backing me up on this one (Hill, 2004, Anderson et al 1999). Think about it logically; if there were a commercial diet that worked and was easy to stick to, no one would be fat. So don't diet. Just think about what you are eating, and eat less of the bad things and more of the good. Oh, and get in half an hour of moderate exercise five times a week. The more desperate of you may choose to consider surgical procedures such as gastric bypass or liposuction, or there are a few (not very nice) drug treatments available.

Alternatively (and this is a motto to live by), just learn to love the skin you're in.

Mouth Ulcers

These are also known as aphthous (taken from the Greek 'aphthi', to set on fire or to burn) ulcers, aphthous stomatitis, and canker sores. These have a large number of different causes, including stress, trauma and food allergy. Despite the fact that smoking is chemically traumatic for your mouth's mucosal layer, it has been found that smokers experience less mouth ulcers than non-smokers. It is thought that this beneficial effect is caused by smokers having increased amounts of keratin in their mucosa that acts as a line of defence against the causes of mouth ulcers (Shapiro, 1970). Interestingly enough, many people actually complain of an onset of mouth ulcers at the same time as giving up smoking. This of course may in part be due to the stressful nature of 'giving up the fags'.

But I don't smoke! How can I help myself?

See a dentist regularly, surround yourself with a calm and relaxed environment and invest in a tube of Bonjela.

Ulcerative Colitis

Ulcerative colitis is a type of inflammatory bowel disease that typically affects the large intestine. It can be a very painful condition, and is thought to autoimmune mediated. In 1982, it was noted by Harris et al that it was a disease of non-smokers, with only 8% of a group of ulcerative colitis patients being regular smokers in comparison to 44% of a control group. This fuelled research into why this should be. It is currently thought that it is nicotine that is producing the beneficial effect. However, trials where patients are treated with nicotine patches have shown there is no advantage in preventing relapses of the condition. The current hypothesis is that smoking and nicotine somehow cause a functional change in nicotinic acetylcholine receptors in the gut (Richardson et al, 2003).

But I don't smoke! How can I help myself?

Look after yourself and eat a nutritionally balanced diet. Take your medication regulary in order to prevent relpases. Consult a doctor if you suspect a relapse and trust in the advice that your gastroenterologist gives you. These guys (usually) know what they're talking about, and they have your best interests at heart.

Mental Health

The prevalence of smoking in the normal population is around 23%. Amongst those diagnosed with psychiatric disorders such a schizophrenia, affective disorders and attention deficit hyperactivity disorder, the prevalence is typically two to four times this number (Sacco et al, 2004). It has been found that heavy smokers with depression and schizophrenia are more likely to rate smoking as a pleasurable activity than heavy smokers in a control group (Spring, 2003). The rates of smoking is particularly high in those diagnosed with schizophrenia. It is thought that this may be because the mesolimbic reward system doesn't function as well in those with schizophrenia, leading to the negative symptoms that many schizophrenics experience. Therefore, self-medication with nicotine allows them to stimulate this area and relieve these symptoms (Chambers et al, 2001).

Also, smoking may act as a temporary relief of the anhedonia (diminished ability to feel pleasure) that is an inherent part of schizophrenia and affective disorders such as depression. The ability of nicotine to activate dopamine release in the mesolimbic reward system is possibly one of the few reinforcers that patients are able to experience as being pleasurable (Fawcett, 1983). Another aspect may be that smoking causes an interaction between the nicotinic acetylcholinergic system and other neurotransmitter systems (e.g. serotonin, glutamate, GABA) that are imbalanced by the two conditions. By self-administering nicotine, patients help to medicate the behavioural, cognitive and mood problems that arise from these disorders (Balfour, Ridley, 2000).

But I don't smoke! How can I help myself?

Exercise. Eat well. Look after yourself. And at the risk of receiving a smack in the face from the next psychiatric patient that I encounter, take the meds. (This has to be the most ineffectual advice I've ever given in my life).

And in anticipation of messages pointing out my failure to include...

Alzheimer's disease

Alzheimer's disease is one of the commonest of the many forms of dementia. It results in cognitive and behavioural impairment, which subsequently leads to problems with social and occupational functioning. Previous case-control studies (Riggs, 1996) have suggested that smoking may have had a preventative benefit with regard to this disease, and so prospective trials were planned.

However, these actually found that the opposite was true; your risk of developing Alzheimer's was actually increased by smoking. In fact, your risk of developing Alzheimer's was doubled. Interestingly, only those who carry APOEε4, an apolipoprotein E genotype, saw no increased risk despite their smoking (Ott, 1998). Research is now being directed into why it is this gene is protective against Alzheimer's in smokers, and how we can manipulate this to society's advantage.

Thank-god I don't smoke! What else can I do?

Numerous studies have shown that those who regularly challenge their brain have decreased rates of Alzheimer's. So keep doing those crosswords, reading those books and arguing with all those who make the mistake of giving you the time of day.

References

• Anderson J W, Vichitbandra S, Qian W, Kryscio R J, 1999, Long-Term Weight Maintenance after an Intensive Weight-Loss Program, J. Amer. Coll. Nutrit., 1999; 18(6):620-627
• Balfour D J K, Ridley D L, 2000, The effects of nicotine on neural pathways implicated in depression: a factor in nicotine addiction? Pharmacol Biochem Behav 2000; 66:79-85
• Castagnoli K P, Steyn S J, Petzer J P, Van der Schyf C J, Castagnoli Jr N, 2001, Neuroprotection in the MPTP Parkinsonian C57BL/6 mouse model by a compound isolated from tobacco. Chem Res 2001; 14: 523-527
• Chambers R A, Krystal J H, Self D W, 2001, A neurobiological basis for substance abuse comorbidity in schizophrenia. Biol Psychiatry 2001; 50:71-83
• Elan L, Luchsinger J A, Tang M X, Richard M D, 2003, Parkinsonian signs in older people: Prevalence and associations with smoking and coffee, Neurology 2003; 61(1): 24-28
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• Grandinetti A, Morens D M, Reed D, et al, 1994, Prospective study of cigarette smoking and the risk of developing idiopathic Parkinson's disease, Am J Epidemiol 1994; 139: 1129-1138
• Harries A D, Baird A, Rhodes J, 1982, Non-smoking: a feature of ulcerative colitis. BMJ 1982; 284:706-706
• Hill A J, 2004, Does dieting make you fat? , Br J Nutr. 2004; 92 Suppl 1:S15-18
• Hofstetter A, Schutz Y, Jequier E, Wahren J, 1986, Increased 24-hour energy expenditure in cigarette smokers, N Engl J Med, 1986; 314:79-82
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• Maggio R, Riva M, Vaglini F, Fornai F, Molteni R, Armogida M, et al., 1998 Nicotine prevents experimental parkinsonism in rodents and induces striatal increase of neurotrophic factors. J Neurochem 1998; 71: 2439-2446
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• Nicklas B J, Tomoyasu N, Muir J, Goldberg A P, 1999, Effects of cigarette smoking and its cessation on body weight and plasma leptin levels, Metabolism 1999; 48(6):804-8
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