Depression causes heart disease? New study unmasks antidepressants as the real culprits
It’s not hard to imagine why someone might feel depressed after a heart attack or stroke that leaves them incapacitated, even temporarily. What’s perhaps harder to figure out is why someone feeling depressed might develop cardiovascular disease (CVD) or see it worsen as a result. However, mainstream scientists are convinced that “the relationship between depression and heart disease is a two-way street,” as an article in John Hopkins Medicine expresses it.
Is the science really settled? A few Chinese researchers have now challenged the prevailing wisdom and published a study linking not depression and heart disease, but rather antidepressants and heart disease, adding yet another serious side effect to the list attached to some of the world’s most widely prescribed drugs.
Who dares to challenge the consensus?
The Chinese scientists begin by describing the standard narrative, which is that there is a “robust association” between MDD (major depressive disorder) and CVD. Studies such as the one upon which John Hopkins Medicine based its article (published in the prestigious Journal of the American Heart Association—AHA) state categorically that, “Depression and poor mental health are associated with premature CVD.”
However, what the scientists found in their research is that once the effect of taking antidepressants is taken into account, the impact of the underlying mental disorder in causing CVD is revealed as negligible:
Notably, after subtracting the effects of antidepressants, the causal influences of MDD on each of the examined CVD were diminished to insignificance, indicating that the effect of MDD on these diseases is primarily accounted for by the concomitant use of antidepressants.
How could John Hopkins researchers and the AHA have missed such a significant factor?
The answer is right there in the AHA study:
... information on antidepressants was not available and so could not be adjusted for in the analysis.
It is unclear why that information should not have been available; it requires no special technique to collect it.
More and more drugs; more and more disease
Depression and other mental (aka emotional) disorders are so prevalent in modern societies that many speak of a “crisis” in mental health. According to the CDC, 1 in 10 people seeing their physician for any reason mention feeling depressed during the visit. Many if not most of these people leave with a prescription for an antidepressant. By 2018 (more up-to-date data are not readily available), 17.7 percent of adult women were taking antidepressants (for men, the figure was lower at 8.4 percent). Almost 1 in every 4 women over the age of 60 was then taking an antidepressant. Those figures are likely to have increased over the past 6 years.
The researchers in this latest study note the significance of so many people being considered (and considering themselves) mentally ill to some extent:
Cardiovascular diseases (CVDs) and mental disorders stand as two major classes of leading causes of death and disability globally, with CVD and depression demonstrating a high degree of comorbidity and collectively ranking as the top two contributors to worldwide disability.
When hard science is 'enigmatic' and yet proven...
Explaining the need for research such as theirs, the scientists note that little if any such research has been done to-date, despite the fact that the “comorbidity” of mental illness and CVD is widely accepted:
Cardiovascular disease (CVD) and mental disorders are highly comorbid, yet the mutual causality between the two broad categories of diseases has yet to be systematically explored.
This, despite the fact that doctors apparently believe that being depressed is strongly linked to the risk of serious and often fatal events such as stroke and heart attack. The Chinese researchers provide links to studies that allegedly give evidence for the link between MDD and CVD, yet when one peruses those studies, there is no concrete evidence provided. Other studies that claim to show a clear link are along the lines of that published by the AHA, which failed to examine the role of antidepressants entirely.
What the standard narrative provides doctors is therefore a conclusive statement based on inconclusive evidence:
While the significant co-occurrence and interplay between MDD and CVD have been acknowledged, the underlying biological mechanisms linking these two conditions remain predominantly enigmatic.
While some have theorized that “systemic inflammation” or “mental stress” leading to immune system disturbance in depressed or otherwise mentally disturbed people may be responsible for developing CVD, there is no firm evidence that this is the case.
What correlates with each type of cardiovascular disease? Antidepressants, not depression
The researchers decided to study a number of mental disorders, including major depression, schizophrenia, insomnia, ADHD, OCD (obsessive-compulsive disorder), PTSD (post-traumatic stress disorder), and anxiety disorder. They also examined many subcategories of CVD such as arrhythmias (irregular heartbeat), hypertension (high blood pressure), coronary artery disease (CAD), heart failure (HF), and stroke.
What they found was that antidepressant use was linked to every single category of CVD that they studied, increasing the risk by an average of 35 percent (OR—odds ratio 1.35).
Our ... analysis demonstrated that the use of antidepressants is correlated with the elevation of respective risks across all cardiovascular conditions. This includes arrhythmias (OR: 1.28), atrial fibrillation (OR: 1.44), coronary artery disease (OR: 1.16), hypertension (OR:1.16), heart failure (OR: 1.16), stroke (OR: 1.44) and entire CVD group (OR:1.35).
Had they not examined the role of antidepressants, the researchers would likely have drawn the same conclusions as others before them who “found” that depression and other mental disorders predispose to CVD and yet could not explain why:
We discovered that major depressive disorder (MDD), attention-deficit/hyperactivity disorder (ADHD) and insomnia exhibit connections with elevated risks of two or more CVDs.
Once the effect of antidepressants was allowed for, the effect of the mental disorder itself on CVD was found to be essentially zero:
MDD [major depressive disorder] itself was not linked to a heightened risk of any CVD...
“Our findings highlight the utilization of antidepressants as an independent risk factor for CVD, thus explaining the influence of MDD on CVD through the mediating effects of antidepressants.
They also found ADHD to be linked to a higher risk of coronary artery disease, heart failure, and CVD in general, but there is no mention in the study of any examination of the role ADHD drugs may play there.
In conclusion, while lifestyle factors (such as insufficient physical activity and unhealthy diet) are acknowledged to be linked to CVD and might be thought to disproportionately affect people suffering depression, the data do not support a link between depression itself and CVD.
Surprise findings — or suppressed findings
As to why antidepressants are linked to cardiovascular disease, the researchers suggested a few areas worthy of research.
Research has demonstrated that antidepressants can impact blood pressure through various mechanisms, encompassing the stimulation of adrenergic, dopaminergic and serotoninergic pathways, along with histamine and choline-dependent systems.
In fact, their findings were not altogether surprising to them, as they write that the cardiovascular risks associated with antidepressants have already been documented in the medical literature (which has somehow been overlooked or dismissed — they do not suggest which):
... the largest increase in cardiovascular risks attributed to the use of antidepressants (44%) was for stroke. These risks are well acknowledged in the literature. For example, in a large Medicare-based study of individuals who suffered from traumatic brain injury, the use of SSRIs [a class of antidepressant] was associated with an increased risk of hemorrhagic stroke (RR: 1.26), with particular emphasis on escitalopram (RR: 1.33) and sertraline(RR: 1.46).
Older antidepressants such as tricyclics (TCAs) have apparently long been known to be linked to a higher CVD risk:
Many of these [commonly prescribed] antidepressants have also been linked to an elevated risk of acquiring cardiovascular conditions. For instance, TCAs have been associated with a higher likelihood of stroke and other cardiovascular adverse events, such as myocardial infarction, arrhythmia, HF and cardiovascular death.
However, newer antidepressants may be just as damaging to cardiovascular health, despite common perception:
Although newer classes of antidepressants, including SSRIs and SNRIs, have been suggested to have safer cardiovascular profiles when compared with TCAs, clinical studies have uncovered an increase in the occurrence of arrhythmias, prolongation of QT interval, hypertension and orthostatic hypotension in the users of newer antidepressants.
In particular, Prozac (fluoxetine) has been linked to high blood pressure and irregular heart rhythm, as have many other commonly prescribed antidepressants:
Fluoxetine has been connected to hypertension and AF [atrial fibrillation]; mirtazapine [Remeron] to an increased risk of hypertension and tachycardia; venlafaxine [Effexor], in a dose-dependent manner, to hypertension; and duloxetine [Cymbalta] to high blood pressure.
Antidepressants >> heart disease >> depression >> antidepressants
The Chinese scientists concluded that physicians should take their findings into account before prescribing antidepressant drugs:
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
When treating patients with antidepressants, it is necessary to take into consideration the potential beneficial and detrimental effects of antidepressants.
This is all the more pertinent as people with CVD are more likely to use antidepressants than people without cardiovascular problems — in fact, they mention “a 74% increased likelihood of antidepressant use associated with overall CVD.”
This is not, they stress, because CVD actually causes mental illness, a theory which has, according to them, been disproven. They suggest other reasons why people receiving a CVD diagnosis may start taking antidepressant drugs, such as becoming depressed without a clinical diagnosis, or “unfavorable socioeconomic conditions that ... increase the risk of depression” — that is to say, people with cardiovascular disease are more likely to become incapacitated and impoverished.
Furthermore, they stress that even in the absence of any mental disorder, use of antidepressants is linked to CVD:
... our ... analysis established the use of antidepressants as an independent risk factor for CVD.
This is vital to take into account as antidepressants are prescribed for (and FDA-approved to treat) conditions beyond depression, including but not confined to: selective mutism, anorexia nervosa, premenstrual syndrome, fibromyalgia, premature ejaculation, various menopause-related conditions, and autism.
We must not investigate as it is 'unethical' to conduct a randomized study
The researchers take pains to note that their study is one of only a very few examining the role of antidepressants in CVD:
... few studies have yet evaluated the potential impact of the confounding influence of antidepressant use on CVD. Therefore, it is largely unknown whether the increased risk of CVD in patients with MDD can be attributed to MDD itself, antidepressant usage or the combination of the two.
They suggest a number of reasons why the research in this area is sparse, one of which is that many scientists consider it unethical to randomize depressed patients to receive either an antidepressant or a placebo and thereby deprive the control group of what is widely believed to be an effective treatment for a serious condition:
... conducting randomized controlled trials that compare patients with depression with and without antidepressant use cannot be accepted from an ethics standpoint.
They also note that quantifying depression is challenging and that any study that measures severity of disease (i.e., mental health) is limited by the inability to quantify emotional suffering.
Investigating the benefits of antidepressants is, however, perfectly permissible
The researchers mention, almost in passing, that studies have however been conducted in an effort to detect a positive influence of antidepressants on cardiovascular health. “No significant benefits” were ever found in these studies.
Why scientists investigated whether antidepressants might prevent CVD and never wondered whether the drugs’ effect might be negative is of course a matter of conjecture.
The information contained in this article is for educational and information purposes only and is not intended as health, medical, financial or legal advice. Always consult a physician, lawyer or other qualified professional regarding any questions you may have about a medical condition, health objectives or legal or financial issues.
If you are struggling with suicidal thoughts, call a qualified free mental health helpline or seek help from a qualified therapist.
