Smoking reduction may reduce suicidality in people with psychotic disorders, according to a new Australian study.
The researchers explored the impact of smoking reduction on suicidal ideation and behavior in 235 adults with a psychotic disorder (bipolar or schizophrenia spectrum) who participated in a randomized trial of a healthy lifestyle intervention. At the start of the trial, all participants had been taking antipsychotic agents as prescribed for a minimum of 2 months and were smoking a minimum of 15 cigarettes per day. Suicidality was assessed based on the Brief Psychiatric Rating Scale (BPRS) at baseline, at 15 weeks (mid-intervention), and at 12 months after baseline.
Following baseline assessment, all participants completed a standardized 90-minute face-to-face intervention session, after which they were randomly assigned to either a face-to-face multicomponent intervention addressing smoking, diet, and exercise or a less intensive, predominantly telephone-based intervention. Both groups were offered nicotine replacement therapy.
There was no significant association between suicidality and treatment group over time (P=.871), so all subsequent analyses were conducted across both treatment groups.
At 15 weeks, no association was found between smoking reduction and suicidality. However, at 12 months researchers found a significant association between smoking reduction and suicidality (total effect, P=.007); associations were also identified between smoking reduction and depression (P=.078), and between depression and suicidality (P<.001).
After adjusting for depression, the association between smoking reduction and suicidality diminished but remained statistically significant (direct effect, P=.034). The researchers estimated that depression accounted for only 30% of the association between smoking and suicidality.
“These findings have potentially important implications,” the researchers commented, since smoking “could be related to an increase in depression” and “smoking cessation is associated with reduced depression.” Moreover, they added, “smoking and depression share common biochemical and neurocognitive abnormalities, such as cognitive inflexibility, that have been shown to be associated with suicidality.”
They noted that, since smoking-associated brain changes may be reversible after smoking cessation, the neurocognitive changes responsible for suicidality over time might also be reversible.
“In addition to physical health impacts, the results of the present study provide a further important reason why clinicians should address smoking in this population,” the researchers concluded.
Sankaranarayanan A, Clark V, Baker A, et al. Reducing smoking reduces suicidality among individuals with psychosis: complementary outcomes from a healthy lifestyles intervention study. Psychiatry Res. In Press. http://dx.doi.org/10.1016/j.psychres.2016.07.006.