Metabolic Syndrome, Obesity, and Suicide in Bipolar Disorder

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CASE VIGNETTE

“Mr Wallace” is a 43-year-old African-American male with an 8-year history of bipolar I disorder, who experienced depression with psychotic features in his most recent episode. He had a history of 3 previous suicide attempts via overdose, all of which were >5 years ago. He had chronic relationship stress with his parents and adult son, whom he felt did not understand his depression. He also had chronic unresolved grief regarding the death of his brother from a myocardial infarction several years ago.

Mr Wallace was obese, with a BMI of 33. He also met the criteria for metabolic syndrome, with increased waist circumference, high triglycerides, low HDL cholesterol, and elevated blood pressure. He saw his psychiatrist monthly, and was adherent with mood stabilizing medication, but reported chronic, passive suicidal ideation without plan or intent. He would often state that he wished he had died instead of his brother. One month after his last outpatient appointment, his family contacted the clinic to report his death by suicide.

Bipolar disorder is associated with increased premature mortality,¹ including cardiometabolic disorders.² There is an increased prevalence of the metabolic syndrome and constellation of risk factors—including abdominal obesity, hypertension, and abnormal glucose and lipid metabolism—associated with cardiovascular disease morbidity and mortality in patients with bipolar disorder.³ There is also an increased prevalence of suicide in patients with bipolar disorder, with an estimated 34% lifetime prevalence of suicide attempt.⁴ One previous study found that suicide attempts were more likely in patients with (versus without) metabolic syndrome and obesity.

The Current Study

Stensel and colleagues⁵ investigated associations between metabolic syndrome, obesity, and suicidality in 215 patients with bipolar disorder who were part of the ongoing BIPLONG longitudinal study.⁶ Diagnosis was made by structured clinical interview by a psychiatrist or clinical psychologist. Inclusion criteria were inpatients and outpatients aged >18 years with complete anthropometric and clinical data. Exclusion criteria were comorbid chronic obstructive pulmonary disease (COPD); autoimmune, neurodegenerative, or neuroinflammatory disease; hemodialysis; and interferon immunotherapy.

Subjects were assessed with the Beck Depression Inventory, the Hamilton Depression Rating Scale, the Young Mania Rating Scale, and lifetime suicidal ideation and suicide attempt. Subjects also had anthropometric measures, vital signs, and fasting blood samples for glucose and lipids. Metabolic syndrome was defined by the International Diabetes Federation criteria (Alberti). BMI was trichotomized as normal (18.5 to 24.9), overweight (25 to 29.9), and obesity (≥30). Data were analyzed using analysis of covariance, controlling for age, sex, and illness duration.

Of the 215 subjects, 52% were male, the mean age was 44 years, and the mean illness duration was 19 years. Sixty-six subjects (31%) met the criteria for metabolic syndrome. One-hundred seventy-four subjects (81%) had current suicidal ideation, and 76 (35%) had at least 1 suicide attempt. Sixty-six subjects (31%) were obese, and 75 (35%) were overweight.

There was no significant association between metabolic syndrome or waist-hip ratio and suicidal ideation or suicide attempt. There was also no significant association between BMI categories and suicide attempt. However, there was a significantly higher prevalence of suicidal ideation in normal weight (88%) versus overweight (71%) and obese plus overweight (77%). Suicidal ideation was positively correlated with glucose and negatively correlated with total and LDL cholesterol, although findings were no longer significant after Bonferroni correction.

Study Conclusions

The authors concluded that there was no significant association between the metabolic syndrome, lipid levels, and suicidality in the study sample. Subjects with normal weight had more lifetime suicidal ideation than the other groups. Study limitations included the cross-sectional study design and the absence of a standardized questionnaire on suicide; the authors also did not control for potential confounding effects of medications.

The Bottom Line

This study did not confirm an association between metabolic syndrome and suicidality in patients with bipolar disorder. However, BMI warrants further investigation as a potential risk marker for suicide in this population.

Dr Miller is a professor in the Department of Psychiatry and Health Behavior at Augusta University in Augusta, Georgia. He is on the Editorial Board and serves as the schizophrenia section chief for Psychiatric Times^TM. The author reports that he receives research support from Augusta University, the National Institute of Mental Health, and the Stanley Medical Research Institute.

References

1. Laursen TM, Wahlbeck K, Hällgren J, et al. Life expectancy and death by diseases of the circulatory system in patients with bipolar disorder or schizophrenia in the Nordic countries. PLoS One. 2013;8(6):e67133.

2. Weiner M, Warren L, Fiedorowicz JG. Cardiovascular morbidity and mortality in bipolar disorder. Ann Clin Psychiatry. 2011;23(1):40-47.

3. Vancampfort D, Vansteelandt K, Correll CU, et al. Metabolic syndrome and metabolic abnormalities in bipolar disorder: a meta-analysis of prevalence rates and moderators. Am J Psychiatry. 2013;170(3):265-274.

4. Dong M, Lu L, Zhang L, et al. Prevalence of suicide attempts in bipolar disorder: a systematic review and meta-analysis of observational studies. Epidemiol Psychiatr Sci. 2019;29:e63.

5. Stenzel C, Dalkner N, Unterrainer HF, et al. Effects of metabolic syndrome and obesity on suicidality in individuals with bipolar disorder. J Affect Disord. 2022;311:1-7.

6. Dalkner N, Bengesser SA, Birner A, et al. Metabolic syndrome impairs executive function in bipolar disorder. Front Neurosci. 2021;15:717824.