One of the things which I’ve learned as I’ve studied depression and mental health is that the connections to depression are stronger and more broad than any of us really are aware. I suppose this shouldn’t be that surprising: After all, nearly one in five Americans actively suffer from some sort of mental illness, and those numbers are only going up. This means that the connections with depression are tragically broader than most of us probably realize.
But, the connections with depression run deeper – and more surprising – than I think any of us are really aware.
I’ve been unpleasantly surprised at how many things are connected to depression. Here are five such items, but with a note of warning straight out of an introduction to psychology class: Correlation does not equal causation. Just because something is connected to depression doesn’t mean it causes depression. The two are connected, but that doesn’t make them causational.
1) Air pollution: Here’s an interesting one. According to a study in England, children who live in high areas of air pollution are significantly more likely to have depression than children who don’t. It is certainly possible that pollution impacts brain development and causes depression, but it’s also possible that the same societal factors which lead to someone living in a polluted area have an impact on someone’s mental health.
2) Migraines: According to the American Migraine Foundation, people who have migraines are five times more likely to develop depression than people without them. Indeed, the more frequently someone has migraines, the more likely they are to develop depression. From a causational perspective, this makes sense, of course: Chronic disorders can have a significantly negative impact on someone’s health and state of mind. But, as the American Migraine Foundation notes, the direction of the link is not clear, and it’s certainly possible that depression can cause migraines, rather than the other way around.
3) Heart disease: This one is unsurprising, but there is a connection between heart disease and depression, and it seems to run both ways. According to the University of Iowa, “While being diagnosed with heart disease or having a heart attack may increase the risk of depression, depression itself may increase the chances of developing heart disease.” In other words, this relationship seems to run both ways.
4) Neuroinflammation: I’ve written about this one before but it is worth repeating: Inflammation of the brain appear together. That’s why anti-inflammatory drugs can help fight depression. Again, the direction of the relationship is at least somewhat unclear, but treating inflammation can help treat depression.
5) Vegetarianism: Of the five items I discuss here, this is the one that took me by the most surprise. A Psychology Today article linked being a vegetarian with depression, noting that there is ample research to suggest that the two are connected. As always, however: The direction of the connection is harder to suss out, and there is evidence to suggest that the two are not connected.