Smoking and mental health - NCSCT

Smoking and mental health
less common, and can be severely disabling. With increasing severity of mental
disorder come, among other things, progressively increased risks of social
stigmatisation and marginalisation, reduced uptake or delivery of health services
for physical illness, an increased risk of tobacco smoking and associated
increased physical illness, and reduced life expectancy. People with mental
disorders are generally around twice as likely to be smokers as those without,
but smoking prevalence increases in relation to disease severity to the extent
that most of those with a psychotic illness smoke. Consequently, of the 10
million smokers in the UK, up to 3 million report evidence of mental disorder,
up to 2 million have been prescribed a psychoactive medication in the past year
and approaching 1 million have longstanding disease. People with mental
disorders are also more likely to be heavily addicted to smoking and, the more
severe the mental disorder, the greater the strength of addiction. Although it is
possible that mental disorder increases the risk of some physical illness
independently of smoking, it is likely that the high prevalence of smoking
accounts for most of the substantially lower life expectancy of people with
mental disorders. In addition to reduced life expectancy, of the order of 10 years
or more, smoking reduces quality of life, exacerbates poverty and adds to social
stigma in this group.
10.3 The nature of the association between smoking and
mental disorders
It is not clear whether the association between mental disorders and smoking is
causal. Longitudinal data suggest that smokers are more likely to develop
depression or anxiety disorder, and there is some evidence of common genetic
determinants of both smoking and specific mental disorders, particularly
depression and schizophrenia. There is also experimental evidence that nicotine
can provide immediate relief from symptoms of anxiety, depression,
schizophrenia and attention deficit hyperactivity disorder (ADHD), although
nicotine withdrawal also creates a range of unpleasant symptoms. People with
these mental disorders may therefore find that smoking helps to ameliorate
symptoms in the short term, and hence be more likely to become smokers;
this may explain the increased risk of smoking among people with behavioural
disorders, anxiety, depression and psychosis. However, in established smokers,
symptoms of nicotine withdrawal, such as depression, anxiety, irritability and
agitation, mimic or exacerbate those of common mental disorders, thus
perhaps accounting for at least some of the increased incidence of diagnoses
of anxiety, depression and other mental disorders among people who smoke.
However, further research to elucidate these associations in more detail is
needed.
190 © Royal College of Physicians 2013