What is mental illness?

There are dozens of different kinds of mental illness, from common disorders that affect tens of millions of people such as depression and anxiety, to rarer afflictions like paraphilia (sexual compulsion) and trichotillomania (a compulsion to remove hair).

The “bible” of mental illness, the Diagnostic and Statistical Manual of Mental Disorders (its fifth iteration, DSM-5, was published in 2013), groups them under about 20 subheadings* (see below).

Mental illness is not sadness, insanity or rage (though it can involve these in some of its forms); it is not binary or exclusive, but complex and universal.

Another way to think of it is as a spectrum, a continuum that we all sit on. At one end is mental health, where we are thriving, fulfilled and at ease. In the middle reaches, people can be described as coping, surviving or struggling. At the far end sit the range of mental illnesses. Most us move back and forth along this line our entire lives.

How widespread is it?

First, to bust some myths: there is no global epidemic. It is not growing exponentially. It is not a disease of western capitalism.

Second, a warning. Data is remarkably patchy. It relies on people self-reporting their feelings, never the best foundation for accurate information.

But insofar as data exists, the most reliable time series curated by the Institute for Health Metrics Evaluation (IHME) appears to show that in 2017, just under 300 million people worldwide suffered from anxiety, about 160 million from major depressive disorder, another 100 million from the milder form of depression known as dysthymia.

Totting up a global figure is not easy, as many people may suffer from more than one condition. According to data from the IHME’s Global Burden of Disease, about 13% of the global population – some 971 million people – suffer from some kind of mental disorder. Dementia is the fastest-growing mental illness.

The British charity Mind refers to a statistic that one in four people will experience some form of mental illness in any given year.

Is it getting worse?

The short answer is not really. The increases in the above graphic are only slightly higher than the rise in global population since 1990.

“All the modelling we’ve done in high-income countries where there is survey data which has tracked over time shows that the prevalence hasn’t changed – it’s flatlined,” says Harvey Whiteford, professor of population mental health at the University of Queensland.

But there have been two big changes in the past 20 years. The first is that recognition and destigmatisation has resulted in a huge surge of people seeking help. The second is that surveys repeatedly show that more young people are reporting mental distress.

“There is much more talk about it and more people being treated,” Whiteford adds. “The treatment rates have gone up. In Australia, they have gone up from about one third of the diagnose population getting treatment to about a half.”

Where is it worst in the world?

No country is immune. No country really stands out as a hellscape either – though mental health data collectors say that countries that have been at war naturally suffer from large numbers of trauma-related mental illness.

One measure of mental illness that has become a gold standard over the past 30 years is the disability adjusted life year (DALY) – a sum of all the years of healthy, productive life lost to illness, be it through early death or through disability.

The DALY metric as compiled by the IHME for all countries of the world shows an interesting top 10:

What causes mental illness?

How long have you got? Myriad volumes have been written on this and yet it remains unresolved. Because it is rarely just one single thing.

Psychiatrists speak of a combination of risk factors that might, repeat might, add up to trouble. Start with the genes.

“What you inherit is a certain vulnerability or predisposition, and if things happen on top of that then people would then be more likely to suffer from a mental problem,” says Ricardo Araya, director of the Centre for Global Mental Health at King’s College. “It’s polygenic, there are lots of genes involved, we know you may have inherited certain genes but it doesn’t necessarily mean you will suffer.”

For example, last year scientists pinpointed 44 gene variants that raise the risk of depression.

Then there are life experiences that compound the risk factor, such as abuse, trauma, stress, domestic violence, adverse childhood experience, bullying, conflict, social isolation or substance abuse (which can be cause and consequence). But it’s not a precise science, says Ann John, professor in public health and psychiatry at Swansea University Medical School.

“One of the things with mental illness is that one risk factor plus a second doesn’t automatically equal a mental illness,” she says.

So which are the most common illnesses?

Clinical depression (which is not the same a feeling a bit down or a bit depressed – that is called being human) is sometimes best described as a series of things lost: loss of joy, concentration, love, hope, enthusiasm, equilibrium, appetite and sleep (though it can also come with overcorrections on both of these).

Depressive disorders, which may affect as many as 300 million people worldwide, account for about one third of mental illness DALYs. There are myriad online diagnostics for self-assessment, though if you feel what might be clinical depression, you should see a doctor.

It is usually treated with a mixture of medication and talking therapy, the former for mood stabilisation, the latter to discover whence it came and how to change ways of thinking to send it on its way.

Anxiety is a close cousin of clinical depression – and again, it is not the same as feeling a bit anxious. It is an uncontrollable, and often inexplicable, surfeit of worry, often experienced as much in the body as in the mind. Acute anxiety can lead to panic attacks and numerous phobias. Anxiety disorders account for about one in seven mental illness DALYs, according to the World Health Organization.

It is usually treated via medication and psychological therapies such as cognitive behavioural therapy.

Bipolar disorder, which affects an estimated 50 million people worldwide, is a disorder that involves extreme mood disturbance. There are two main types: bipolar I involves episodes of severe mania and depression; bipolar II is characterised by more frequent periods of depression with fewer – and less intense – manic episodes.

Schizophrenia is characterised by “delusions, hallucinations, disorganised speech and behaviour, and other symptoms that cause social or occupational dysfunction,” according to DSM-5. It affects an estimated 20 million people worldwide.

Substance abuse. “Substance use disorder” is considered a mental illness and gets its own chapter in DSM-5. Not every user of intoxicating substances will qualify – only those struggling with control, compulsion and withdrawal when not using. But that is still estimated to be more than 150 million people worldwide.

Some substance abuse may trigger other mental illnesses listed here and elsewhere; some other mental illnesses may lead to substance abuse, because of self-medication.

Alcohol and illicit drugs are included; tobacco is not. Alcohol- and drug-use disorders account for almost one fifth of mental illness DALYs. Of major countries, Russia and the US have the highest per capita rates.

Post-traumatic stress disorder is one of a number of trauma- and stress-related disorders, and is usually caused by experiencing a stressful event that is then relived, sometimes many years after it happened. It can result in a series of symptoms common to depression such as loss of concentration, sleep, mood, temper, control and energy.

Eating disorders such as anorexia nervosa and bulimia nervosa account for about 1% of mental illness DALYs. About 3 million people worldwide are thought to suffer from anorexia.

Dementia is a neurocognitive disorder that results in a decline in brain function and concomitant impairments in thinking, remembering and reasoning. It affects an estimated 50 million people worldwide, up from about 20 million in 1990.

Who is best at treating mental illness?

Mental illnesses services are inadequate pretty much everywhere. But some countries are more inadequate than others.

According to WHO data, Turkey and Belgium are the only countries that have more than 100 mental health nurses for every 100,000 people. Ninety countries have fewer than 10.

The situation is even worse with psychiatrists. Thirty nations, almost all of them developed and most of them in Europe, have more than 10 psychiatrists per 100,000 people (Norway is top of the list with 48). Seventy countries have fewer than one.

Japan tops the list for mental health beds in mental health facilities (196 per 100,000), and is third behind Hungary and Germany for mental health beds in general hospitals. Britain is 50th for mental health beds per capita, behind China, Uzbekistan and Lebanon.

What about medication?

It’s a highly contested area, for three reasons. Firstly, mental health drugs are big business – worth an estimated $80bn (£63bn) a year worldwide.

Secondly, they are no panaceas. Some people respond better to drugs than others.

Thirdly, the prescription of drugs has surged in recent years, particularly antidepressants such as selective serotonin reuptake inhibitors (SSRIs) – drugs such as Prozac that have become hugely popular since the 1990s. In several countries, there has been concern that they are prescribed too readily, to people with only mild symptoms.

That said, they also work. A metastudy published last year found that they worked better than placebos.

A range of new treatments is promising to move psychopharmacology beyond SSRIs. From ketamine to psilobycin, new psychotropic compounds offer both the promise of remedy – and the worry of self-medication.

So are mental illnesses still taboo?

Less than they used to be. It could be said that the subject has moved from being invisible to being taboo to being openly discussed in the space of 30 years.

But mental illnesses are still not universally accepted. People with mental illnesses still complain of discrimination; 300,000 people with long term mental health problems lose their jobs every year – and that’s just in the UK.

And while disorders like depression and anxiety are becoming more accepted by the public, schizophrenia, personality disorders and psychosis are still poorly understood.

Appendix

The 20 chapters of DSM-5 are: Neurodevelopmental Disorders; Schizophrenia Spectrum and Other Psychotic Disorders; Bipolar and Related Disorders; Depressive Disorders; Anxiety Disorders; Obsessive-Compulsive and Related Disorders; Trauma- and Stressor-Related Disorders; Dissociative Disorders; Somatic Symptom Disorders; Feeding and Eating Disorders; Elimination Disorders; Sleep-Wake Disorders; Sexual Dysfunctions; Gender Dysphoria; Disruptive, Impulse Control and Conduct Disorders; Substance Use and Addictive Disorders; Neurocognitive Disorders; Personality Disorders; Paraphilic Disorders; Other Disorders

• Contact the Samaritans on the freephone number 116 123. You can call even if you don’t have credit on your mobile, and the number won’t show up on phone bills. Or you can email jo@samaritans.org or go to www.samaritans.org to find details of your nearest branch, where you can talk to a trained volunteers face to face.

In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international suicide helplines can be found at www.befrienders.org