Smoking and Anxiety Panic Attacks

LUNG cancer, hypertension, heart disease, birth defects—we're all too familiar with the perils of smoking. But add to that list a frightening new concern. Mental illness. According to some controversial new findings, if smoking doesn't kill you, it may, quite literally, drive you to despair. 

The tobacco industry openly pushes its product as something to lift your mood and soothe anxiety. But the short-term feel-good factor may mask the truth: that smoking may worsen or even trigger anxiety disorders, panic attacks and depression, perhaps even schizophrenia.

Cigarettes and mental illness have always tended to go together. An estimated 1.25 billion people smoke worldwide including roughly a quarter of Britons and Americans. Yet people who are depressed or anxious are twice as likely to smoke, and up to 88 per cent of those with psychotic disorders such as schizophrenia are smokers. A recent American survey concluded that around half of all cigarettes burn in the fingers of those with mental illness.

But the big question is why? The usual story is that the illness comes first. Mentally ill people take up smoking, or smoke more, to alleviate some of their distress. Even when smoking seems to start before the illness, most doctors believe that early but invisible symptoms of the disorder spark the desire to light up. But perhaps something more sinister is going on.

A growing band of researchers claim that smoking is the cause, not the consequence of clinical depression and several forms of anxiety. “We know a lot about the effects of smoking on physical health, and now we are also starting to see the adverse effects in new research on mental illness,” says epidemiologist Naomi Breslau, director of research at the Henry Ford Health Care System in Detroit.

Breslau was one of the first to consider this heretical possibility. The hint came from studies, published in 1998, which followed a group of just over 1000 young adults for a five year period. The 13 per cent who began the study with major depression were around three times more likely to progress from being light smokers to daily smokers during the course of the study, though there was no evidence that depression increased the tendency to take up smoking. But a history of daily smoking before the study commenced roughly doubled the risk of developing major depression during that five-year period. Smoking, it seems, could pre-date illness.

At first Breslau concluded that whatever prompts people to smoke might also make them depressed. But as the results of other much larger studies began to back the statistical link, she became more convinced than ever that what she was seeing were signs that smoking, perhaps the nicotine itself, could somehow affect the brain and cause depression.

One of these larger studies was led by Elizabeth Goodman, a paediatrician at the Children's Hospital Medical Center in Cincinnati. She followed the health of two groups of teenagers for a year. The first group of 8704 adolescents were not depressed, and might or might not have been smokers, while the second group of 6947 were highly depressed and had not been smokers in the past month.

After a year her team found that although depressed teenagers were more likely to have become heavy smokers, previous experimentation with smoking was the strongest predictor of such behaviour, not the depression itself. Crucially though, teenagers who started out mentally fit but smoked at least one packet per week during the study were four times more likely to develop depression than their non-smoking peers. Goodman says depression doesn't seem to start before cigarette use among teens. “Current cigarette use is, however, a powerful determinant of developing high depressive symptoms.”

True, it's a disturbing statistical correlation. But just because smoking starts before depression, does that make it the cause? Couldn't the traditional interpretation, that people use cigarettes to self-medicate, still hold true? Perhaps an incipient malaise before symptoms become apparent could be enough to prompt the urge to light up.

Indeed, lots of anecdotal evidence suggests smoking comes before the illness in most people with schizophrenia. But equally, plenty of data shows that smoking damps down the side effects of schizophrenia drugs and even eases some of the symptoms. That makes causal links extremely difficult to untangle. Especially when you realise that the neurochemical and neuronal anomalies underlying schizophrenia might very well appear in the brain long before any obvious symptoms. Smoking needn't be the cause of subsequent problems. But it's vital we find out.

Since they started noticing the trend for smoking to pre-date depression and to some extent schizophrenia, other researchers have taken a long hard look at epidemiological data on other mental health conditions. Karen Lasser of the Cambridge Hospital and Harvard Medical School in Boston published a large-scale study a little over a year ago detailing the smoking habits and mental health of almost 4500 people between the ages of 15 and 54. She says her findings confirm the idea that mental illness encourages smoking. But she also found that smokers had a higher risk of subsequently developing depression, panic attacks and longer-term anxiety disorders such as agoraphobia. She shares Goodman's feeling that we can't ignore the obvious implication, that smoking is a cause rather than a consequence of these problems.

Breslau, too, finds that smokers are as much as four times more likely to have an isolated panic attack and three times more likely to develop longer-term panic disorder than non-smokers. It's a hard message to get across, because many smokers say they become anxious when they quit, not when they smoke. But Breslau says this is a short-lived effect of withdrawal which masks the reality that, in general, smokers have higher anxiety levels than non-smokers or ex-smokers. Not only that, but anxious people, she found, were no more likely to take up smoking after their symptoms developed than people without their problems. That's enough to convince Breslau that cigarettes may be triggering the problem.

Inevitably it will take more than suspicion and statistics to prove the link. But a more detailed look at anxiety disorders has only fanned the flames. Both Breslau and Jeffrey Johnson of New York State Psychiatric Institute at Columbia University find that certain mental conditions are linked with breathing difficulties that might be triggered or at least exacerbated by smoking.

Johnson and his team found that people in good mental health who smoked a packet or more of cigarettes a day at age 16 were 16 times more likely to develop panic disorder, 7 times more likely to become agoraphobic and 5 times more likely to develop generalised anxiety disorder (GAD) than people who stuck to less than one pack a day. And because anxious adolescents weren't any more likely than non-anxious teenagers to become adult smokers, it's more likely that smoking is a cause, not a consequence, says Johnson.

Smoking, says Johnson, seems to be associated with exactly the group of anxiety conditions that have recently been found to be linked to respiratory disorders. And conditions that are not linked with smoking—such as obsessive compulsive disorder or social anxiety disorder are probably not affected by breathing problems either. This, he believes, is the key to why smoking can affect the mind.

Smoking can mess up breathing to such an extent that it triggers a condition called “false suffocation”, says Donald Klein, one of Breslau's colleagues. It's the high levels of carbon monoxide in cigarette smoke that are responsible. And this feeling leads to panic. Breslau points out that serious lung disease may also trigger feelings of suffocation and raise the risk of panic attacks.

Johnson believes that panic attacks caused by breathing difficulties that are triggered or heightened by smoking could play a role in longer-term anxiety disorders too. “Agoraphobia is very similar to panic disorder,” he says. “Many people with it have panic attacks or panic-like symptoms, and these episodes probably play a crucial role in precipitating and maintaining other symptoms of agoraphobia.”

But breathing difficulties aren't the only problem with smoking. He also believes the stimulant effects of nicotine itself could play a part. The state of high arousal, rapid breathing and heart rate and raised blood pressure, especially in people who chain-smoke, may be indistinguishable from anxiety.

And we do have other reasons to believe that nicotine can influence the brain directly. David Balfour, professor of behavioural pharmacology at Dundee University and an expert on nicotine's action on the brain, says that large amounts of nicotine make rats more anxious. It may do this by affecting brain chemicals such as the neurotransmitter dopamine. Other drugs which increase dopamine levels induce anxiety, he says. So why not nicotine? Goodman adds: “The fact that Zyban is effective in the treatment of depression and as a smoking cessation aid suggests a common neurochemical pathway.”

Even so, Balfour is not convinced that epidemiological studies go far enough to show that smoking is a cause rather than a consequence of mental illness. In rats at least, nicotine only induces anxiety in very high doses—the sort of levels only the most dedicated chain-smokers could achieve. He still believes the most likely explanation for high smoking rates in people with depression and schizophrenia is self-medication. “People with schizophrenia may use chronic exposure to nicotine to normalise the mechanisms which underlie the disease.” A recent study found that people with schizophrenia had a reduced number of nicotinic receptors—sites on brain cells that may be vital for the normal passage of signals through the brain. This could be one factor that underlies the compulsion to smoke.

Balfour also points out that more than 70 per cent of alcoholics are heavy smokers, and believes that this alone may account for the statistical correlation between smoking and mental illness. Alcoholism is classified as a mental illness itself, but also exacerbates many other forms of mental distress.

Important and worrying as claims that smoking causes mental illness may be, Balfour thinks that we need to know a lot more about what nicotine does in the brain before we can draw that conclusion.

Whether or not you choose to believe the causal link, it's clear that more studies are vital. If smoking raises the risk of mental ill health even a fraction, the number of casualties would be enormous. Yet there's still so much we don't know. It's improbable that smoking alone can cause mental illness—other environmental or genetic factors surely play their part. But which ones?

Passive smoking and exposure before birth may also be damaging, but any link is still highly controversial. Studies suggest that the children of women who smoked during pregnancy have an increased risk of psychiatric problems, including substance abuse and hyperactivity, so it's possible nicotine and maybe some of the other 4000 or so chemicals found in tobacco smoke can damage delicate developing brains. We desperately need to examine the wider effects of smoking in pregnancy alongside broader epidemiological, genetic and neurobiological studies. They will need to look for interactions between smoking and psychiatric medications, and critical periods or exposure levels that might prove dangerous.

And even if cause and effect are still cloudy, Lasser and other researchers are concerned that little is being done to help the large number of mentally ill smokers to quit. Psychiatric wards are often a fog of smoke, and cigarettes are sometimes even used as “currency”—doled out as reward or withheld as punishment.

At the moment, the tobacco industry seems disinclined to discuss the possibility that smoking might cause mental illness. British American Tobacco (BAT) declined to comment, but the tobacco industry clearly has other things on its mind. As smoking rates peak or fall in the West, the major players are striking back, expanding their operations in Eastern Europe, Asia, Latin America and Africa. A BAT document explains: “We should not be depressed simply because the total free world market appears to be declining.” If the epidemiologists are right, and smoking does underlie some forms of mental illness, the tobacco industry may soon be looking hard for reasons to be cheerful.