In every single country we looked at, consumption of anti-depressants has risen since 2000. But where has it risen the fastest? And does the rise necessarily say something about mental health?

When it comes to mental health, definition varies massively from country to country - and it changes over time. Homosexuality was listed as a sociopathic personality disorder in America until 1974 and it was in the Chinese Classification of Mental Disorders until 2001.

Those differences make it hard to find reliable data on mental health, so most studies rely on survey data instead. But there is one way to see how understanding of, and reaction to mental health has changed: antidepressants.

We looked at anti-depressant consumption in 25 countries around the world. This is what we found.

What if anything is the correlation with suicide rates?

1 in 10 people in Iceland take antidepressants daily

When we looked at the daily consumtion of antidepressants per 1,000 people, Iceland stood apart from any other country we looked at with 106 per 1,000 consuming these drugs in 2011. It's also important to bear in mind that those figures are calculated per 1,000 of the population, not per 1,000 adults, meaning that the actual rate of antidepressant consumption is likely to be even higher.

According to the Nordic Medico- Statistical Committee (Nomesco), age and gender plays a key role too. In 2008, almost 30% of women aged 65 and over had an antidepressant prescription in Iceland, compared with less than 15% in Norway.

The map below is shaded to show the rate of antidepressant consumption – hover over a country to see the actual rates per 1,000 people.

Iceland was also the highest consumer of antidepressants in 2000, though the overall numbers were much lower – 71 per 1,000 people. The historical data for all countries shows just how consistent the upward trend has been (there's an animated graph at the bottom of this article that shows antidepressant use since 1980 – but you will need to have flashplayer installed).

Various reasons are put forward by experts to explain why this is the case. From drug treatments lasting longer, to a weakening of social taboos and greater willingness to seek treatment – there are several factors that affect consumption. That's partly because medical advice has changed, the World Health Organisation has a recommendation (and classed it as a strong one) that "the antidepressant treatment should not be stopped before 9 -12 months after recovery".

Another explanation for the rise in antidepressant consumption, put forward by European academics in 2012 is that it is linked to the increase in insecurity that was triggered by the financial crisis. But caution is needed – there was a rapid rise in the use of these drugs in Spain and Portugal, but it rose even more quickly in Germany (up 46% between 2007 and 2011) a country that was more insulated from the effects of the economic downturn.

American responses: prescriptions or counsellors?

In the US, almost 40% of people with mental health issues received treatment in 2012. But data from the US department of health also shows the types of treatments they received - from psychologists to prescription medication (including antidepressants). This is how it breaks down.

Like other countries, the use of antidepressants in the US has soared. In 1998, 11.2 million Americans used these drugs. By 2010, it was 23.3 million. Despite that rise, expenditure on antidepressants has barely risen as the drugs have become cheaper – from $624 per person in 1998, to $651 in 2010.

Sexual orientation matters when it comes to health – so the US department of health collects data to see what the trends are. In terms of major depression, the gaps are enormous.

Chinese boom

China's national health department doesn't publish statistics on antidepressants. But Menet, a private company does collect numbers on this. They found that in 2011, 36 million people in China suffered from depression, but only 10% accepted treatment. Despite that, sales of antidepressants had reached 2.61bn, up 19.5% from the previous year.

Image: Menet

The other side of the story

The results might sound different though when we present them as the percentage of the population that do not take antidepressants. Using a different data source this time – the Eurobarometer survey which asked around 27,000 individuals – we're able to see consumption of these drugs in the past year, in the past month and over their entire lives.

In Greece, 97% of people have never taken these drugs – scroll down and you'll see that in Portugal it's 84%. But switch view by clicking at the top and you'll see a very different story in drug trends. In eastern Europe, taking these drugs from "time to time" is a far more frequent occurrence than it is in western Europe.

Do you think any of this data provides a reliable indication of mental health – or the treatment for illnesses? Have a look at what we found, and tell us what you think below.