A mental disorder is characterized by a clinically significant disturbance in an
individual’s cognition, emotional regulation, or behaviour. It is usually associated with
distress or impairment in important areas of functioning. There are many different types
of mental disorders. Mental disorders may also be referred to as mental health
conditions. The latter is a broader term covering mental disorders, psychosocial
disabilities and (other) mental states associated with significant distress, impairment in
functioning, or risk of self-harm. This fact sheet focuses on mental disorders as
described by the International Classification of Diseases 11th Revision (ICD-11).
In 2019, 1 in every 8 people, or 970 million people around the world were living with a
mental disorder, with anxiety and depressive disorders the most common (1). In 2020,
the number of people living with anxiety and depressive disorders rose significantly
because of the COVID-19 pandemic. Initial estimates show a 26% and 28% increase
respectively for anxiety and major depressive disorders in just one year (2). While
effective prevention and treatment options exist, most people with mental disorders do
not have access to effective care. Many people also experience stigma, discrimination
and violations of human rights.
Anxiety Disorders
In 2019, 301 million people were living with an anxiety disorder including 58 million
children and adolescents (1). Anxiety disorders are characterised by excessive fear
and worry and related behavioural disturbances. Symptoms are severe enough to result
in significant distress or significant impairment in functioning. There are several different
kinds of anxiety disorders, such as: generalised anxiety disorder (characterised by
excessive worry), panic disorder (characterised by panic attacks), social anxiety
disorder (characterised by excessive fear and worry in social situations), separation
anxiety disorder (characterised by excessive fear or anxiety about separation from
those individuals to whom the person has a deep emotional bond), and others. Effective
psychological treatment exists, and depending on the age and severity, medication may
also be considered.
Depression
In 2019, 280 million people were living with depression, including 23 million children and
adolescents (1). Depression is different from usual mood fluctuations and short-lived
emotional responses to challenges in everyday life. During a depressive episode, the
person experiences depressed mood (feeling sad, irritable, empty) or a loss of pleasure
or interest in activities, for most of the day, nearly every day, for at least two weeks.
Several other symptoms are also present, which may include poor concentration,
feelings of excessive guilt or low self-worth, hopelessness about the future, thoughts
about dying or suicide, disrupted sleep, changes in appetite or weight, and feeling
especially tired or low in energy. People with depression are at an increased risk of
suicide. Yet, effective psychological treatment exists, and depending on the age and
severity, medication may also be considered.
Bipolar Disorder
In 2019, 40 million people experienced bipolar disorder (1). People with bipolar disorder
experience alternating depressive episodes with periods of manic symptoms. During a
depressive episode, the person experiences depressed mood (feeling sad, irritable,
empty) or a loss of pleasure or interest in activities, for most of the day, nearly every
day. Manic symptoms may include euphoria or irritability, increased activity or energy,
and other symptoms such as increased talkativeness, racing thoughts, increased self-
esteem, decreased need for sleep, distractibility, and impulsive reckless
behaviour. People with bipolar disorder are at an increased risk of suicide. Yet effective
treatment options exist including psychoeducation, reduction of stress and
strengthening of social functioning, and medication.
Post-Traumatic Stress Disorder (PTSD)
The prevalence of PTSD and other mental disorders is high in conflict-affected settings
(3). PTSD may develop following exposure to an extremely threatening or horrific event
or series of events. It is characterised by all of the following: 1) re-experiencing the
traumatic event or events in the present (intrusive memories, flashbacks, or
nightmares); 2) avoidance of thoughts and memories of the event(s), or avoidance of
activities, situations, or people reminiscent of the event(s); and 3) persistent perceptions
of heightened current threat. These symptoms persist for at least several weeks and
cause significant impairment in functioning. Effective psychological treatment exists.
Schizophrenia
Schizophrenia affects approximately 24 million people or 1 in 300 people worldwide
(1). People with schizophrenia have a life expectancy 10-20 years below that of the
general population (4). Schizophrenia is characterised by significant impairments in
perception and changes in behaviour. Symptoms may include persistent delusions,
hallucinations, disorganised thinking, highly disorganised behaviour, or extreme
agitation. People with schizophrenia may experience persistent difficulties with their
cognitive functioning. Yet, a range of effective treatment options exist, including
medication, psychoeducation, family interventions, and psychosocial rehabilitation.
Eating Disorders
In 2019, 14 million people experienced eating disorders including almost 3 million
children and adolescents (1). Eating disorders, such as anorexia nervosa and bulimia
nervosa, involve abnormal eating and preoccupation with food as well as prominent
body weight and shape concerns. The symptoms or behaviours result in significant risk
or damage to health, significant distress, or significant impairment of functioning.
Anorexia nervosa often has its onset during adolescence or early adulthood and is
associated with premature death due to medical complications or suicide. Individuals
with bulimia nervosa are at a significantly increased risk for substance use, suicidality,
and health complications. Effective treatment options exist, including family-based
treatment and cognitive-based therapy.
Disruptive behaviour and dissocial disorders
40 million people, including children and adolescents, were living with conduct-dissocial
disorder in 2019 (1). This disorder, also known as conduct disorder, is one of two
disruptive behaviour and dissocial disorders, the other is oppositional defiant disorder.
Disruptive behaviour and dissocial disorders are characterised by persistent behaviour
problems such as persistently defiant or disobedient to behaviours that persistently
violate the basic rights of others or major age-appropriate societal norms, rules, or laws.
Onset of disruptive and dissocial disorders, is commonly, though not always, during
childhood. Effective psychological treatments exist, often involving parents, caregivers,
and teachers, cognitive problem-solving or social skills training.
Neurodevelopmental disorders
Neurodevelopmental disorders are behavioural and cognitive disorders, that? arise
during the developmental period, and involve significant difficulties in the acquisition and
execution of specific intellectual, motor, language, or social functions.
Neurodevelopmental disorders include disorders of intellectual development, autism
spectrum disorder, and attention deficit hyperactivity disorder (ADHD) amongst others.
ADHD is characterised by a persistent pattern of inattention and/or hyperactivity-
impulsivity that has a direct negative impact on academic, occupational, or social
functioning. Disorders of intellectual development are characterised by significant
limitations in intellectual functioning and adaptive behaviour, which refers to difficulties
with everyday conceptual, social, and practical skills that are performed in daily life.
Autism spectrum disorder (ASD) constitutes a diverse group of conditions characterised
by some degree of difficulty with social communication and reciprocal social interaction,
as well as persistent restricted, repetitive, and inflexible patterns of behaviour, interests,
or activities.
Effective treatment options exist including psychosocial interventions, behavioural
interventions, occupational and speech therapy. For certain diagnoses and age groups,
medication may also be considered.
Who is at risk from developing a mental disorder?
At any one time, a diverse set of individual, family, community, and structural factors
may combine to protect or undermine mental health. Although most people are resilient,
people who are exposed to adverse circumstances – including poverty, violence,
disability, and inequality – are at higher risk. Protective and risk factors include
individual psychological and biological factors, such as emotional skills as well as
genetics. Many of the risk and protective factors are influenced through changes in
brain structure and/or function.
Health systems and social support
Health systems have not yet adequately responded to the needs of people with mental
disorders and are significantly under resourced. The gap between the need for
treatment and its provision is wide all over the world; and is often poor in quality when
delivered. For example, only 29% of people with psychosis (5) and only one third of
people with depression receive formal mental health care (6).
People with mental disorders also require social support, including support in
developing and maintaining personal, family, and social relationships. People with
mental disorders may also need support for educational programmes, employment,
housing, and participation in other meaningful activities.
WHO response
WHO’s Comprehensive Mental Health Action Plan 2013-2030 recognizes the essential
role of mental health in achieving health for all people. The plan includes 4 major
objectives:
to strengthen effective leadership and governance for mental health;
to provide comprehensive, integrated and responsive mental health and social
care services in community-based settings;
to implement of strategies for promotion and prevention in mental health; and
to strengthen information systems, evidence, and research for mental health.
WHO's Mental Health Gap Action Programme (mhGAP) uses evidence-based technical
guidance, tools and training packages to expand services in countries, especially in
resource-poor settings. It focuses on a prioritized set of conditions, directing capacity
building towards non-specialized health-care providers in an integrated approach that
promotes mental health at all levels of care. The WHO mhGAP Intervention Guide 2.0
is part of this Programme, and provides guidance for doctors, nurses, and other health
workers in non-specialist health settings on assessment and management of mental
disorders.
