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About mental health disorders

There are as many different types of mental health disorders as there are physical disorders. With just as many nuances, variables and contributing factors.


This page gives an insight into some of the most common mental health disorders and their effects.

Mental ill health and its effects

Research study authors asked over 60,000 global participants which diseases, injuries and disorders they considered the most disabling. They used this data to create a ‘disability weight’ for each condition.


A disability weight is a number ranging from 0.0 to 1.0 which represents the severity of a disease, with larger numbers representing increasing severity/disability. The paper ranks 185 physical and mental health conditions from least to most disabling, including:

  • HIV/AIDS in treatment = 0.08

  • Mild depression = 0.15

  • Moderate epilepsy = 0.26

  • Moderate dementia = 0.38

  • Moderate depression = 0.40

  • Severe motor impairment = 0.40

  • Severe anxiety = 0.52

  • Severe stroke with long-term consequences = 0.55

  • Severe depression = 0.66

  • Untreated spinal cord lesion/injury = 0.73

  • Schizophrenia (acute) = 0.78


Salomon JA et al.: Disability weights for the Global Burden of Disease 2013. 

The impact of mental ill health



+ 1 in 4 people experience mental health issues each year


+ 676 million people are affected by mental health issues worldwide


+ Mental illness is the largest single source of burden of disease in the UK. Mental illnesses are more common, long-lasting and impactful than other health conditions


+ The total cost of mental ill health in England is estimated at £105 billion per year


+ 75% of mental illness (excluding dementia) starts before age 18


+ Men aged 40-49 have the highest suicide rates in Great Britain


+ 70-75% of people with diagnosable mental illness receive no treatment at all

In the workplace


+ 1 in 6 workers will experience depression, anxiety or problems relating to stress at any one time


+ There were 526,000 cases of work-related stress, depression or anxiety in 2016/17 in Great Britain


+ In 2016/17, stress was responsible for 40% of all cases of work-related ill health and for 49% of all working days lost due to health issues in GB


+ 1 in 5 people take a day off due to stress. Yet, 90% of these people cited a different reason for their absence


+ Presenteeism accounts for 2 times more losses than absences


+ Every year it costs business £1,300 per employee whose mental health needs are unsupported

Mental ill health is responsible for 72 million working days lost and costs £34.9 billion each year. Different studies will estimate the cost of mental ill health in different ways. Other reputable research estimates this cost to be as high as £74–£99 billion


+ People with a long-term mental health condition lose their jobs every year at around double the rate of those without a mental health condition. This equates to 300,000 people – the equivalent of the population of Newcastle or Belfast


+ 15% of employees who disclosed mental health issues to their line manager reported being disciplined, dismissed or demoted


+  84% of UK line managers believe they are responsible for employee wellbeing, but only 24% have received training. 49% of line managers reported a wish for basic training in common mental health conditions 



+  Mental ill health is the largest cause of burden of disease in the UK 


+  The economic costs of mental health issues in England have been estimated at £105 billion each year 


+  In an average classroom, ten children will have witnessed their parents separate, eight will have experienced severe physical violence, sexual abuse or neglect, one will have experienced the death of a parent and seven will have been bullied 


+  Half of mental ill health starts by age 15 and 75% develops by age 18 


+  12.8% of young people aged 5-19 meet clinical criteria for a mental health disorder 


+  Women between the ages of 16 and 24 are almost three times as likely (26%) to experience a common mental health issue as males of the same age (9%) 


+  The proportion of young people aged 15-16 who reported feeling depressed or anxious doubled between the mid-1980s and the mid-2000s 


+  About 20% of young people with mental ill health wait more than six months to receive care from a specialist 


+  In a 2015 OECD survey of 15-year-olds, the UK ranked 23rd for life satisfaction, out of a total of 28 OECD countries 


+  About 10% of young people aged 8-15 experience a low sense of wellbeing


+  Only one in eight children who have been sexually abused come to the attention of statutory agencies 


+  Up to 25% of teenagers have experienced physical violence in their intimate partner relationships 

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