Alcohol, substance abuse doubles suicide risk in bipolar disorder

By Laura Cowen, medwireNews Reporter

Patients with bipolar disorder and comorbid alcohol and substance use disorders are twice as likely to attempt suicide as those without such comorbidity, results of a systematic review and meta-analysis show.

The findings, “underline the importance of prevention, early detection and aggressive treatment of [alcohol and substance use disorders] in individuals with [bipolar disorder] to reduce suicidality”, remark Francesco Bartoli (University of Milano-Bicocca, Monza, Italy) and colleagues.

The researchers reviewed data from 29 studies comprising 31,294 individuals with bipolar disorder, 6308 (20.1%) of whom had attempted suicide.

Thirteen of the studies, involving 19,062 individuals, looked at the association between a lifetime history of alcohol and/or substance use disorders (found in 20% of participants) and suicide attempts. The pooled odds ratio for these studies was 1.96, with moderate to high heterogeneity (64.3%).

Four of the studies focussed on current alcohol and/or substance use disorders in 3418 patients, but the pooled analysis of these highly heterogeneous studies (88.4%) showed no significant association with suicide attempts.

This suggests that “more enduring comorbidity is associated with higher risk”, write Bartoli and co-authors in the Journal of Affective Disorders.

A lifetime history of alcohol use disorders was associated with a 1.72-fold increased likelihood of suicide attempts in the 10,723 individuals included in the 18 studies with relevant data. A subanalysis of three studies that differentiated between alcohol abuse and dependence gave similar odds ratios for both, at 1.64 and 1.70, respectively.

Similar results were also observed for substance use disorders (13 studies, 7952 participants), with individuals who reported a lifetime history of substance use disorders being 1.77 times more likely to have attempted suicide than those without this comorbidity.

Data on specific types of substance abuse were limited but four studies did provide information on the relationship between cannabis use and suicide attempts in bipolar patients. Pooling the data from these studies indicated that lifetime cannabis use was associated with a 1.44-fold increased likelihood of suicide attempts.

The researchers say that this finding “lends credibility” to the association between cannabis use and suicide risk and “suggests that cannabis use can have serious consequences for individuals with [bipolar disorder].”

The team notes that insufficient information meant that they could not investigate how alcohol and substance use disorders affect the number and type (violent vs non-violent) of suicide attempts and that this is a limitation of the study.

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