Suicidal Thoughts Linked to Low Blood Pressure

Megan Brooks

March 05, 2018

Low blood pressure may increase the risk for suicidal ideation, new research shows.

Among more than 10,000 South Korean adults, those with systolic blood pressure (SBP) <100 mm Hg were at higher risk of having suicidal thoughts compared to their peers with normal blood pressure.

"Although previous studies suggested that low blood pressure is associated with neuropsychological problems, including depression and anxiety, no studies have investigated the association between low blood pressure and suicidal ideation, which is an indicator of a negative psychiatric state," Sung-il Cho, MD, from Seoul National University, said in a statement.

"Our findings suggest that the health implications of low blood pressure may need to be evaluated to take into account potential adverse effects on mental health," added Cho.

The study was published online March 1 in BMC Public Health.

More Common in Women

The researchers analyzed data on 10,708 adults who participated in the 2010-2013 Korean National Health and Nutrition Examination Survey. Overall, 1199 (11.2%) had experienced suicidal ideation, identified by asking one of two questions: "Have you ever felt inclined to commit suicide over the last year?" (2010-2012) and "Have you ever considered suicide seriously over the last year?" (2013).

Suicidal ideation was more common in women than men (12.9% vs 7.8%) and in those aged 70 years and older (20.8%).

The researchers used four cutoff values to define low blood pressure: SBP <110 mm Hg, <100 mm Hg, <95 mm Hg, and <90 mm Hg. Altogether, 2569 (24%) adults had low blood pressure, and 8139 (76%) had normal blood pressure.

According to the investigators, 10.8% of people with normal blood pressure had experienced suicidal ideation. For people with low SBP, this proportion increased to 12.5% in those with SBP <100 mm Hg, 13.7% in those with SBP <95 mm Hg, and 16.6% in those with SBP <90 mm Hg.

Compared with the normotensive reference group, the likelihood for suicidal ideation was significantly higher in those hypotensive groups with SBP <100 mm Hg, < 95 mm Hg, and < 90 mm Hg after adjusting for sex, age, body mass index, total cholesterol level, household income, educational level, marital status, current smoking status, alcohol intake, and the interaction between sex and age.

Table. Association of Low SBP With Suicidal Ideation

SBP Group Odds Ratio (95% CI)
<110 mm Hg 1.03 (0.85 - 1.24)
<100 mm Hg 1.29 (1.08 - 1.82)
<95 mm Hg 1.44 (1.14 - 1.82)
<90 mm Hg 1.71 (1.11 - 2.62)
CI, confidence interval

 

Further adjustment for diabetes, stroke, myocardial infarction/angina pectoris, and depression as covariates had little effect on the strength of these associations, the researchers say. No significant association was found between prehypertension or hypertension and suicidal ideation.

"Although prehypertension may be a risk factor for cardiovascular diseases and should be managed, it does not appear to have a negative impact on mental health. Low blood pressure may pose different health issues compared to high blood pressure, and our study challenges the perception that in terms of mental health, lower blood pressure is really always better," said Cho.

The researchers caution that this is a cross-sectional study and cannot prove a causal relationship between low blood pressure and suicidal ideation. Also, the use of self-reported survey data may have introduced information and recall bias. In addition, because only levels of SBP were used to define low blood pressure, future studies are needed to explore the relationship between suicidal ideation and diastolic blood pressure.

Despite these limitations and caveats, the researchers note that the findings are in line with several earlier studies suggesting a correlation between low blood pressure and psychological symptoms, such as depression and anxiety.

Taken together, the results support the "BP-emotional dampening hypothesis," which suggests that BP has an inhibitory effect on overall negative emotional experience and pain perception, they write.

Further research is needed into the possible biological mechanisms that may explain the association between blood pressure and suicidal ideation, they add.

More Research Needed

Commenting on the study for Medscape Medical News, Tze Pin Ng, MBBS, PhD, research director, Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, noted that this is the latest study in a "thin line of research which supports the possible adverse health effects of low blood pressure. For many decades, this possibility has been met with mostly skepticism and largely ignored except in a few European countries.

"This is the first study that was able to support the link between low blood pressure and adverse mental health by showing an association with suicidal ideation. I see it as another strong nail in the woodwork. But we need many more studies with longitudinal design and brain MR imaging to establish strong causality for this association," said Ng.

The study had no funding. The authors have disclosed no relevant financial relationships.

BMC Public Health. Published online March 1, 2018. Full text

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