February 05, 2019
2 min read

Tobacco use linked to psychotic experiences in adolescence

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Tobacco use appeared to be associated with psychotic experiences — such as paranoia and hallucinations — during adolescence, largely due to shared genetic influences, according to study findings.

“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,” Angelica Ronald, PhD, professor of psychology and genetics at Birkbeck, University of London, said in a press release. “In particular, we do not really know why tobacco use and mental health problems often co-occur.”

Researchers reported findings from the first twin study examining the degree to which tobacco use and psychotic experiences (paranoia, hallucinations, cognitive disorganization, grandiosity and anhedonia) shared genetic or environmental influences in adolescents.

Participants reported on psychotic experiences and regularity of tobacco use, and parents rated the twins’ negative symptoms. Researchers conducted regression analyses adjusted for sociodemographic characteristics, prenatal maternal smoking, cannabis use, sleep disturbances and stressful life events. The investigators used bivariate twin modeling to estimate the degree of genetic, common and unique environmental influences shared by tobacco use and psychotic experiences.

Of 3,610 teens who reported the regularity of their tobacco use in the past year, 2,985 (82.7%) were nonsmokers, 436 (12.1%) occasional smokers and 189 (5.2%) regular smokers.

The results showed that regular smokers were more likely than nonsmokers to experience paranoia (P < .001), hallucinations (P < .001), cognitive disorganization (P < .001), grandiosity (P = .002), and negative symptoms (P < .001), but not anhedonia (P = .061). Similarly, occasional smokers were more likely than nonsmokers to have paranoia (P < .001), hallucinations (P = .002) and cognitive disorganization (P < .001) but less likely to have anhedonia (P = .023). However, there were no significant differences in grandiosity and parent-rated negative symptoms.

When compared with occasional smokers, regular smokers were more likely to have all types of psychotic experiences, including paranoia (P = .006), hallucinations (P < .001), cognitive disorganization (P < .001), grandiosity (P = .018), anhedonia (P = .001), and negative symptoms (P < .001).

These associations remained after accounting for covariates including gender, socio-economic status, cannabis use, prenatal maternal smoking, sleep disturbances and stressful life events, according to the press release.

Unadjusted regression models demonstrated that regular smoking significantly predicted higher scores on all psychotic experience subscales compared to not smoking.

Ronald and colleagues also observed significant genetic correlations and that genetic influences accounted for most of the correlation between tobacco use and paranoia (84%) and cognitive disorganization (81%). Furthermore, familial influences accounted for 80% of the link between tobacco use and hallucinations, according to the results.

“Our results suggest that some of the same genetic factors that influence tobacco use in adolescents also influence [psychotic experiences],” the researchers wrote in the full study. “We have provided novel insights into the etiology of the covariation between some [psychotic experiences] and tobacco use that may inform further molecular genetic studies and developmental models.” – by Savannah Demko

Disclosure: Ronald reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.