Insomnia and suicide risk in cluster B personality disorder: A comparative cross-sectional study
Objective The suicide mortality rate among people suffering from cluster B personality disorders is estimated at approximately 20%. High occurrence of comorbid depression and anxiety, as well as substance abuse, are known contributors to this risk. Not only have recent studies indicated that insomnia may be a suicide risk factor, but it is also thought to be highly prevalent in this clinical group. However, the mechanisms explaining this association are still unknown. It has been suggested that emotion dysregulation and impulsivity may mediate the link between insomnia and suicide. In order to better understand the association between insomnia and suicide in cluster B personality disorders, it is important to consider the influence of comorbidities. The aims of this study were first to compare the levels of insomnia symptoms and impulsivity between a group of patients with cluster B personality disorder and a healthy control group and second, to measure the relationships between insomnia, impulsivity, anxiety, depression, substance abuse and suicide risk within the cluster B personality disorder sample. Methods Cross-sectional study including 138 patients (mean age = 33.74; 58.7% women) with cluster B personality disorder. Data from this group were extracted from a Quebec-based mental health institution database (Signature bank: www.banquesignature.ca) and were compared to that of 125 healthy subjects matched for age and sex, with no history of personality disorder. Patient diagnosis was determined by diagnostic interview upon admission to a psychiatric emergency service. Anxiety, depression, impulsivity and substance abuse were also assessed at that time point via self-administered questionnaires. Participants from the control group visited the Signature center to complete the questionnaires. A correlation matrix and multiple linear regression models were used to explore relations between variables. Results In general, more severe insomnia symptoms and higher levels of impulsivity distinguished the group of patients with cluster B personality from the sample of healthy subjects, although groups did not differ on total sleep time. When all variables were included as predictors in a linear regression model to estimate suicide risk, subjective sleep quality, lack of premeditation, positive urgency, depression level and substance use were significantly associated with higher scores on the Suicidal Questionnaire-Revised (SBQ-R). The model explained 46.7% of the variance of scores at the SBQ-R. Conclusion This study yields preliminary evidence indicating the possible implication of insomnia and impulsivity in suicide risk for individuals with cluster B personality disorder. It is proposed that this association seems to be independent of comorbidity and substance use levels. Future studies may shed light on the possible clinical relevance of addressing insomnia and impulsivity in this clinical population.