Can We Link Personality Pathology with Smoking & Traits?

Research Paper Title

Predicting smoking and nicotine dependence from the DSM-5 alternative model for personality pathology.

Background

Individuals with personality disorders (PDs) have higher morbidity and mortality than the general population, which may be due to maladaptive health behaviours such as smoking.

Previous studies have examined the links between categorical PD diagnoses/personality traits and smoking/nicotine dependence, but little is known about how the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition alternative model for personality disorders relates to smoking and nicotine dependence.

Methods

The current study examined this question in a sample of 500 participants using the Levels of Personality Functioning Scale to assess general personality pathology, the Personality Inventory for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition to measure specific traits, the Fagerström test for Nicotine Dependence to assess nicotine dependence, and questions about current and past smoking to assess smoking status (i.e. current, former, never).

Results

Multinomial logistic regression results demonstrated that general personality pathology (Criterion A) was not related to smoking status, and there were no reliable associations between traits (Criterion B) and smoking status. However, correlations showed that higher negative affectivity and disinhibition were related to higher levels of nicotine dependence within smokers.

Conclusions

Findings are discussed in regard to previous findings linking personality pathology to smoking/nicotine dependence as well as the general validity of this new personality disorder diagnostic system.

Reference

Halberstadt, A.L., Skrzynski, C.J., Wright, A.G.C. & Creswell, K.G. (2021) Predicting smoking and nicotine dependence from the DSM-5 alternative model for personality pathology. Personality Disorders. doi: 10.1037/per0000487. Online ahead of print.

Schizophrenia & Smoking Traits

Research Paper Title

Colocalisation of association signals at nicotinic acetylcholine receptor genes between schizophrenia and smoking traits.

Background

Epidemiological data suggest that smoking may be a risk factor for schizophrenia (SCZ), but more evidence is needed. Two regions coding nicotinic acetylcholine receptor (nAchR) subunits, atCHRNA2 and the CHRNA5/A3/B4 cluster, were associated with SCZ in genome-wide association studies (GWAS). Additionally, a signal at CHRNA4 is near significance. CHRNA2 was also associated with cannabis use disorder (CUD). These regions were also associated with smoking behaviours. If tobacco is a risk factor, the GWAS signals at smoking behaviours and SCZ have to be due to the same causal variants, i.e. they have to colocalise, although colocalisation does not necessarily imply causality. Here, we present colocalisation analysis at these loci between SCZ and smoking behaviours.

Methods

The Bayesian approach implemented in coloc was used to check for posterior probability of colocalisation versus independent signals at the three loci with some evidence of association with SCZ and smoking behaviours, using GWAS summary statistics. Colocalisation was also assessed for positive control traits and CUD. Three different sensibility analyses were used to confirm the results. A visualisation tool, LocusCompare, was used to facilitate interpretation of the coloc results.

Results

Evidence for colocalisation of GWAS signals between SCZ and smoking behaviours was found for CHRNA2. Evidence for independent causal variants was found for the other two loci. CUD GWAS signal at CHRNA2 colocalises with SCZ and smoking behaviours.

Conclusions

Overall, the results indicate that the association between some nAchR subunit genes and SCZ cannot be solely explained by their effect on smoking behaviours.

Reference

Al-Soufi, L. & Costas, J. (2021) Colocalization of association signals at nicotinic acetylcholine receptor genes between schizophrenia and smoking traits. Drug and Alcohol Dependence. doi: 10.1016/j.drugalcdep.2021.108517. Online ahead of print.