INSIGHTS | 1. Link between Osteoporosis and Heart Disease.

As people get older, their bones tend to lose density and become more fragile. Fractures of bone insufficiency are very common in the elderly, and often devastating.

Photo by Sergey Kuznetsov on Unsplash

Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781192/

Summary

As people get older, their bones tend to lose density and become more fragile. Fractures of bone insufficiency are very common in the elderly, and often devastating.

Similarly, as people age their cardiovascular disease (CVD) burden increases.

According to the authors (with thorough summary of each study), there is an epidemiologic link between low bone mineral density (BMD) and increased CVD. One study states:

This association was not age-related, was independent of shared risk factors between BMD and [atherosclerotic] calcifications, and was not influenced by estradiol [hormonal].

They even review studies which demonstrate a strong correlation between BMD and subclinical atherosclerosis - this is atherosclerosis seen on testing, but does not manifest in observable dysfunction of health.

The authors go on to state that:

Traditionally, these two conditions were considered unrelated...and attributed to age-related processes. However, recent evidence from many studies points to a link...that cannot be explained by age alone.

Researchers have tested several hypotheses asserting a shared risk factor. But even after accounting for things like:

• smoking

• physical activity

• alcohol intake

• menopause

• hypertension

...the association remained even after adjusting for these. The assumption is that a common factor must be causing both.

The authors also summarized research looking at common inflammatory markers, hormonal influence, and even lipid peroxidation.

A growing body of evidence suggests a negative effect of an atherogenic lipid profile on bone formation.

Near the end of their thorough review, the authors seem to glimmer at the cause.

The reduced blood flow hypothesis assumes that atherosclerosis, by reducing blood flow to the lower extremities, could affect interosseous blood circulation.

...one histological study of 100 cadavers, reported the existence of atherosclerotic changes in interosseous arteries and arterioles of the femur.

Commentary

The authors quite neatly laid out the available evidence to show that there is an independent connection between osteoporosis and cardiovascular disease.

Importantly, they point out that much of the prior research assumed that there was a common risk factor which causes both osteoporosis and cardiovascular disease. I cannot think of a reason why someone should not start from this assumption, at least before entertaining others later.

At the very end of the review, however, the authors spend a rather unsatisfying amount of time considering a hypothesis with a different assumption: that atherosclerosis is causing osteoporosis. That they were correlated because they were causally linked.

How? Well, to understand that, let's look at another part of the body that suffers from vascular disease - the brain.