Depressed? Check your blood pressure!

The link between depression and cardiovascular health is well-known although the mechanism behind the relationship is not well-understood.

A study by Dutch researchers may just give us an idea of the complexity of that link. For one thing, contrary to the common perception that depression can lead to hypertension, depression, is, in fact, associated with low blood pressure. However, medications against depression – the so-called anti-depressants can increase blood pressure. In particular, tricyclic antidepressants (TCAs) can increase the risk for hypertension.

According lead author Carmilla Licht

“Doctors should at least be aware of a potential blood-pressure rise that could be linked to TCA use, especially for patients with cardiovascular disease or high blood pressure or others who are at risk for hypertension…They may consider meticulously monitoring these patients’ blood pressure when they prescribe one of these antidepressants or consider prescribing another antidepressant medication.”

The results of the study are somewhat controversial because they contradict the current “depression-hypertension theory.”

The study was part of the Netherlands Study of Depression and Anxiety, and followed up 2618 participants aged 18 to 65 years old. The study participants were divided into 3 groups:

• Control group without history of anxiety or depression
• Patient group with a major depressive disorder (MDD) but not on antidepressants
• Patients with MDD and on antidepressants

Patients were monitored for systolic blood pressure (SBP) and diastolic blood pressure (DBP) and distinction was made between different types of antidepressants, e.g. selective serotonin-reuptake inhibitors (SSRIs) vs tricyclic antidepressants (TCAs).

The study also observed that a typical patient with psychiatric disorder “were a little older, more likely to be female, less educated, less physically active, smoked more, and had a higher body-mass index and more diseases.”

The study results showed that compared with health controls, MDD patients have significantly lower blood pressure. However, MDD patients on TCA had significant higher blood pressure. The use of SSRIs doesn’t seem to be associated with blood pressure measurements.

So the next question is

Is it the depression that lowers the blood pressure or is it the low blood pressure that causes the depression?

The authors speculate that three things might influence the depression-low blood pressure link.

• Use of anti-hypertensive drugs
• Common causes of depression and low blood pressure, e.g. fluctuations in metabolites, hormones or neurotransmitters
• Low blood pressure can cause depressive symptoms, e.g. fatigue, dizziness, low tolerance to cold temperatures, and concentration problems.

While depression is associated with low blood pressure, the study shows that anxiety is linked to high blood pressure. This, the authors say, might be due to continuous stress associated with anxiety.

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