There is a general assumption that mental illness is on the rise. It is easy to understand why. Prime Ministers talk about it. BBC, ITV and Channel 4 have all had "mental health weeks" and there are dozens of mental health awareness days around the globe.
These coincide with a dramatic rise in students seeking counselling, perhaps unsurprising as 80% of higher education students report high levels of stress. Demand is increasing for mental health services, with psychological therapy services, adult community mental health teams and psychiatric liaison services dealing with more people than ever before.
But none of this means that the true rates of mental disorders have increased. It could all be explained by increased awareness and decreased stigma.
The only way to know if there really has been an increase in the prevalence of mental disorders is to conduct long term and painstaking research. This means surveying randomly chosen large samples of the public, and do so over many years. Only then can you distinguish between a rise in those seeking help from a real rise in the disorders. This week sees the publication of the latest instalment of just such a survey - the "Adult Psychiatric Morbidity Survey" which provides us with the definitive statistical picture of the mental health of the adult nation.
The results are reassuring and concerning. Reassuring because once again the rates of the most severe disorders, such as psychosis and autism, have not gone up. Similarly, the overall rates of more "common" disorders such as depression, anxiety, phobias and obsessive compulsive disorder have remained stable with one in six adults currently affected.
But beneath the headline figures there are worrying trends. The proportion of the population who report having self-harmed has trebled since the year 2000 to 6% with more than a quarter of children and young women aged 16-24 saying that they have self-harmed. There has also been a dramatic increase, mainly in anxiety disorders, in young women - 19% in 1993 to 26% in 2014. Compared to the much smaller changes in men (8% in 1993 to 9.1% in 2014), this means the gender gap has widened significantly.
For those in middle age the concern is harmful drinking. In my age group (55-64) rates of harmful drinking are at their highest rates in this century. And the experience of suicidal thoughts has nearly tripled from 1.9% in 2007 to 5.3% in 2014 with a doubling of suicide attempts. Men in my age-group have the highest rate of suicide nation-wide.
So what is going on? It is difficult to say but a multitude of factors are likely to be at play. Let's consider young adults. Social media is undoubtedly one of the biggest changes in how young people live their lives. And there have been plenty of claims that this might be behind the rise in anxiety and depression.
A recent ONS report found that children who spent more than three hours on social media were twice as likely to report poor mental health. A third of young people who are unhappy with their appearance also reported mental ill-health, compared to one in 12 of those who were happy with how they looked. Cyber-bulling is a factor (bullying of any sort is definitely associated with later depression) but also the sense of constant surveillance from peer groups and pressure to portray a perfect life.
Lots of people will have lots of other explanations. For example experiences of abuse and assault are more common in young women, and now the new data finds much higher rates of post-traumatic stress disorder (PTSD) in women compared to men (13% compared to 4%). Others will point to increasing pressure to perform at school and university, plus the introduction of tuition fees causing financial strain on this generation of students.
Before we leap to conclusions we need to guard against making spurious correlations. By this I mean comparing two trends that happen over the same period and where the figures seem to mirror each other. It may be for instance that the increase in the salaries of footballers have gone up at the same rate and at the same time as - say - the audience for the Great British Bake Off. That doesn't mean there is a causal link between those two things. So we must be very wary about making connections between the rise in some common mental disorders and other changes in society. Correlation does not demonstrate cause.
The obvious response to these figures is simply to call for more investment in mental health services, and we echo that. We are so far behind other chronic diseases, such as cancer or diabetes, in regards to proportion of people in need getting any treatment at all, that there really is no other response. But at the same time, we also need to step back and think about what might be behind these trends, and what social and cultural factors may be involved. For example, some have argued that simply offering more counselling services to students may not be the only solution and others think that it might be, paradoxically, reducing resilience rather than increasing it.
There is one thing we can agree. Getting better answers to the questions we are all asking requires proper evidence. So we need high quality research such as the Adult Psychiatric Morbidity Survey to ensure that where we do invest in services, we have the evidence to ensure that treatments really do deliver what they promise.
Sir Simon Wessely, President of the Royal College of Psychiatrists.