Smoking may be a sign of psychiatric illness, experts say. Doctors should routinely consider referring people who smoke to mental health services, in case they need treatment, they add.

The controversial recommendation from the British Lung Foundation, a charity, comes in response to a major report, Smoking and Mental Health, published this week by the Royal College of Physicians and the Royal College of Psychiatrists with the Faculty of Public Health. It says that almost one in three cigarettes smoked in Britain today is smoked by someone with a mental disorder. When people with drug and alcohol problems are included the proportion is even higher.

The reason is that smoking rates have more than halved over the past 50 years, but the decline has not happened equally in all parts of society.

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“Smoking is increasingly becoming the domain of the most disadvantaged: the poor, homeless, imprisoned and those with mental disorder. This is a damning indictment of UK public health policy and clinical service provision,” the report says.

Of the ten million smokers in Britain, up to three million have a mental disorder, up to two million have been prescribed a psychoactive drug in the past year and approaching one million have longstanding [mental] disease, it says.

While smoking rates among the general public have fallen dramatically, from 56 per cent in men and 42 per cent in women in the early 1960s to 21 per cent in both sexes today, they have hardly changed among people with mental disorders and remain at over 40 per cent.

Professor Stephen Spiro, deputy chair of the British Lung Foundation, said persuading people with mental disorders to give up smoking was a major challenge. But so was identifying smokers who might need psychiatric treatment.

“Routinely considering whether someone presenting with a lung disease, or indeed any patient who smokes, might benefit from referral to mental health services, could make the key difference for many individuals,” Professor Spiro said.

Smoking increases with the severity of mental disorder, and amongst those with a psychotic illness almost all smoke. Nicotine appears to provide some relief from symptoms of anxiety, depression and attention deficit hyperactivity disorder which may explain why people with these conditions become smokers.