Smoking cigarettes in adolescence associated with paranoia

New research from Birkbeck’s Department of Psychology shows an association between regular cigarette smoking in adolescence and paranoia, even after accounting for several other possible factors.

New research from Birkbeck indicates an association between regular cigarette smoking in adolescence and paranoia, which the scientists say is largely explained by genetic influences.

The study, led by Professor Angelica Ronald from the Department of Psychology, found similar results for other types of psychotic experiences were also reported, including having hallucinations and disorganised thinking, which were also associated with tobacco use in teenagers.

Professor Ronald said: “While the links between drugs such as cannabis, paranoia and hallucinations have been reported before, much less is known about the relationship between tobacco use and mental health problems.

“These new findings show that using tobacco is, to some degree, heritable and that some of the same genetic influences that impact on tobacco use also play a role in experiences such as feeling paranoid. It will be exciting to pursue this finding further to unpack the mechanisms that lead to this association.”

The findings are based on the Twins Early Development Study, a large sample of twins born in England and Wales between 1994- 1996.

More than 3,700 adolescent twin pairs took part in this study when they were aged 16. Of these, 31.4% reported smoking cigarettes within the past year, with 12.1% of the sample identifying as occasional smokers and 5.2% as regular smokers.

Adolescents reported on their paranoia and other experiences such as having hallucinations and disorganised thinking, while their parents reported on issues such as a lack of motivation, social withdrawal, and their teenager seeming emotionally flat. These types of psychotic experiences and behaviours are common in adolescence and there is significant variability in how severe they are across individuals.

The researchers found that the frequency of adolescent cigarette smoking was associated with having experiences such as paranoia, with regular smokers having more psychotic symptoms and experiences than non-smokers and occasional smokers. The associations remained even after accounting for several other possible factors such as gender, socio-economic status, cannabis use, prenatal maternal smoking, sleep disturbances and stressful life events.

Environmental influences were thought to account for about two-thirds of the differences in adolescent smoking behaviour, and a third of the differences were due to genetic influences.

The authors urge caution in interpreting the findings. They note that the reported association between tobacco use and psychotic experiences was modest and that their study does not show whether tobacco use causes or worsens psychotic symptoms and experiences, only that they are associated with one another. Nevertheless, the findings could be important because, if confirmed, tobacco use could be a modifiable risk factor for psychosis. Adolescence is an important stage of life when the brain is still developing and individuals can be vulnerable to mental health problems including psychosis. As such, understanding factors related to tobacco use is important and can contribute to changes in public policy.

The research is published in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP). 

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