Chart: Scandinavians take a lot of antidepressants. That might be a good sign.

Is Scandinavia all fun and reindeer games until winter comes and throws everyone into deep depression?

This chart of antidepressant use in Europe certainly suggests that could be the case:

But the truth is likely more complicated. Even though Scandinavian countries, along with other northern nations such as Iceland and the UK, are heavily represented at the top of the chart, that doesn’t necessarily mean that long, dark winters are leaving everyone in those countries depressed.

After all, Iceland isn’t that much darker than Norway — it gets about an hour less of sunlight per day around the winter solstice, when days are shortest — but its rate of antidepressant use is nearly twice as high. And according to the OECD, which supplied the data for the chart above, nearly 30 percent of Icelandic women over 65 had an antidepressant prescription. By contrast, in Norway, the equivalent rate was only about 15 percent. Likewise, antidepressant use in sunny, southern Portugal beats that of Sweden, Finland, Norway, and the UK, even though it has much longer days.

So what’s going on? In fact, many different factors affect a country’s rate of antidepressant use. The prevalence of depression is just one of them.

For instance, high usage rates could actually be a reflection of better access to mental health care. To use antidepressants, a patient typically needs a doctor who will prescribe them, and a way to afford the drugs. So what looks like an increased incidence of depression could actually be an increased incidence of high-quality mental health care, and/or a system that subsidizes the cost of medications. In other words, it could be a good sign instead of a bad one.

Differing medical cultures might also play a role. The OECD notes that there is great variation in “prescribing behavior” from country to country, as well as between individual practitioners. The higher incidence of antidepressant usage in some countries could, therefore, be evidence of local rules that encourage doctors to use antidepressants as a first-line treatment, or to keep patients on them longer.

It could also mean that some countries are more willing than others to use antidepressants as a treatment for problems such as social phobia or anxiety. That would show up as a higher antidepressant usage rate, but wouldn’t actually indicate a higher incidence of depression.

Regardless of the reason, however, rates of antidepressant use have been growing in all European countries in recent years: according to the OECD, rates of antidepressant use across the EU have increased by 80 percent over the last decade.