Whats is Mental Disorders?

Updated 2 years ago on April 08, 2023

Basic facts

  • One in eight people in the world lives with a mental disorder
  • Mental disorders are accompanied by significant disturbances in thinking, emotional regulation or behavior
  • There are many different types of mental disorders
  • There are effective ways to prevent and treat mental disorders
  • Most people do not have access to effective assistance

A mental disorder is characterized by clinically significant impairment of cognitive function, emotional regulation, or behavior of the individual. It is usually accompanied by distress or severe functional impairment. There are many different types of mental disorders Mental disorders are also referred to as mental health disorders. Mental health disorder is an umbrella term that includes mental disorders, various types of psychosocial disabilities and other mental pathological conditions that involve significant distress, functional impairment or risk of self-harm. In this fact sheet, mental disorders are discussed according to the definitions given in the International Classification of Diseases Revision 11 (ICD-11).

In 2019, one in eight people on the planet, a total of 970 million people, had a mental disorder, with anxiety and depressive disorders being the most common. In 2020, with the COVID-19 pandemic, the number of people suffering from anxiety and depressive disorders increased significantly. According to preliminary estimates, in one year alone, the prevalence of anxiety and major depressive disorders increased by 26% and 28%, respectively. Despite the availability of effective prevention and treatment methods, most people with mental disorders do not have access to effective medical care. Many also face stigma, discrimination, and human rights violations.

Anxiety disorders

In 2019, 301 million people, including 58 million children and adolescents, had an anxiety disorder. Anxiety disorders are characterized by feelings of intense fear and anxiety and associated behavioral disorders. At the same time, the symptoms are very serious and lead to significant distress or significant functional impairment. There are several varieties of anxiety disorders, such as generalized anxiety disorder (characterized by excessive feelings of anxiety), panic disorder (characterized by panic attacks), social anxiety disorder (characterized by excessive fear and anxiety in social contacts), separation anxiety disorder (characterized by excessive fear or anxiety in connection with separation from people with whom there is a strong emotional connection) and some others. There are a number of effective methods of psychological aid, in addition to which, depending on the age of the patient and the degree of severity of the disorder detected, medication can be prescribed.


In 2019, 280 million people suffered from depression, including 23 million children and adolescents. Depression is different from normal mood swings or short-term emotional reactions to difficult situations in everyday life. A depressive episode is characterized by a worsening of mood (represented by sadness, irritability, feelings of emptiness) or a loss of interest in any activity for most of the day, almost every day, for at least two consecutive weeks. A number of other symptoms may be present, such as decreased concentration, abnormal feelings of guilt or low self-esteem, lack of faith in the future, thoughts of death or suicide, sleep disturbances, changes in appetite or body weight, and feelings of extreme fatigue or loss of energy. People with depression are at high risk for suicide. Nevertheless, there are a number of effective methods of psychological help, in addition to which medication can be prescribed depending on the age of the patient and the severity of depression.

Bipolar disorder

In 2019, 40 million people suffered from bipolar disorder. People with bipolar disorder are characterized by alternating depressive and manic symptoms. During a depressive episode, there is a worsening of mood (expressed as sadness, irritability, feelings of emptiness) or a loss of interest in any activity for most of the day, almost every day. During a manic episode, elevated mood or irritability, a burst of energy and an excessive desire for activity, and some other symptoms such as increased talkativeness, "idea jumps," increased self-esteem, decreased need for sleep, distractibility, and impulsive rash actions may be noted. Individuals with bipolar disorder are at high risk for suicide. That said, there are effective ways to help, including psychoeducation, techniques to reduce stress and improve various measures of social functioning, and medication.

Post Traumatic Stress Disorder (PTSD)

The prevalence of PTSD and other mental disorders is particularly high in countries affected by armed conflict. PTSD can be the result of an individual's exposure to a situation of extreme danger or to an extremely traumatic mental event or series of events. PTSD is characterized by (1) re-experiencing the traumatic event(s) (intrusive memories, flashbacks or nightmares); (2) avoidance of thoughts and memories of the event(s) or avoidance of activities, situations or people that recall the event(s); and (3) a persistent sense of increased threat level. These symptoms persist for at least several weeks and lead to significant functional impairment. There are effective methods of psychological aid.


Schizophrenia affects about 24 million people, or 1 in 300 people worldwide. Life expectancy for people with schizophrenia is 10-20 years lower than average. Schizophrenia is characterized by significant disturbances in the perception of reality and changes in behavior. Symptoms may include persistent delusions, hallucinations, disorganized thinking, significant behavioral disorganization, or extreme agitation. People with schizophrenia also often experience persistent cognitive impairment. Nevertheless, there are a number of effective treatments for schizophrenia, including medication, psychoeducation, family therapy, and psychosocial rehabilitation.

Eating disorders

In 2019, 14 million people suffered from eating disorders, including nearly 3 million children and adolescents. Eating disorders, such as anorexia nervosa and bulimia nervosa, are characterized by eating abnormalities and preoccupation with food, as well as pronounced anxiety about weight and appearance. These symptoms or behaviors pose a risk of serious harm to health and result in significant distress or significant functional impairment. Anorexia nervosa often begins in adolescence or early adulthood and is associated with premature death due to medical complications or suicide. People with bulimia nervosa have a significant risk of substance abuse, suicidal ideation and health problems. There are effective ways to help, including family therapy and cognitive therapy.

Asocial behavior and dissociative disorders

In 2019, 40 million people, including children and adolescents, suffered from dissociative disorder. This type of disorder, also known as conductive disorders, is one of two subtypes of antisocial behavior and dissociative disorders along with defiant deviant disorder. Asocial behavior and dissociative disorders are characterized by persistent behavioral disturbances, such as persistent provocative or hostile behavior that is systematically accompanied by violations of basic rights of others or basic social norms, rules, or laws that apply to the age group in question. Asocial and dissociative disorders usually begin to develop during childhood, although there may be exceptions. There are effective psychological methods of assistance, often involving parents, caregivers and teachers, which are based on a cognitive approach to problem-solving and social skills training.

Developmental disorders of the central nervous system

Developmental disorders of the central nervous system include behavioral and cognitive disorders that occur during development and are accompanied by significant difficulties in the acquisition and implementation of certain thinking, motor, speech or social skills.

This group of disorders includes, but is not limited to, intellectual disability, autism spectrum disorders and attention deficit hyperactivity disorder (ADHD). ADHD is characterized by persistent concentration and/or hyperactivity/impulsivity difficulties that have a direct negative impact on academic or vocational performance or social functioning. Intellectual development disorders are characterized by significant limitations in cognitive function and adaptive behavior, which is reflected in difficulties in mastering and implementing conceptual, socialandpracticalskills in daily life. Autism spectrum disorders (ASDs) are a multifaceted group of conditions characterized by varying degrees of difficulty in social communication and social interaction, as well as a number of limited, repetitive and inflexible patterns of behavior, interests or activities.

There are a variety of effective methods of assistance, including psychosocial and behavioral interventions, occupational therapy, and speech therapy. Medication therapy may also be prescribed for some diagnoses and age groups.

Who is at risk of developing mental disorders?

A combination of certain individual, family, community, and structural factors can both protect mental health and undermine it. Although most people are mentally resilient, people who are exposed to disadvantages such as poverty, violence, disability, and inequality may be at increased risk for mental health problems. Protective and risk factors include individual psychological and biological factors, such as emotional skills and genetics. Many of the risk and protective factors are influenced by structural or functional changes at the brain level.

Health and social support systems

Health care systems are not yet responding appropriately to the needs of people with mental disorders and face significant resource constraints. Globally, there is a significant gap between the need for care and the amount of care provided, and the quality of care provided is often suboptimal. For example, only 29% of people with psychosis and only one-third of people with depression receive formal psychiatric and psychological care.

People with mental illness also need social supports, including support for forming and maintaining personal, family and social relationships. People with mental illness may also need support for education, employment, housing and opportunities to participate in other meaningful activities.

WHO activities

The 2013-2030 Comprehensive Mental Health Action Plan recognizes the critical role of mental health in achieving health for all people. The plan has four main goals:

  • Strengthening effective mental health leadership and management;
  • Providing a comprehensive, integrated and responsive system of community-based mental health and social support services;
  • Implementation of mental health promotion and mental health prevention strategies;
  • Strengthening information systems, collecting evidence, and conducting mental health research.

WHO's Mental Health Gap Action Programme (mhGAP) is working to develop evidence-based technical guidelines, toolkits and training kits to enhance services in countries, particularly in low-resource settings. The program focuses on the priority list of mental health disorders and aims to build the capacity of non-specialized health workers as part of a comprehensive approach to mental health at all levels of care. The WHO mhGAP Intervention Guide 2.0 is part of this programme and is a practical guide for physicians, nurses and other non-specialist health workers on how to assess and treat mental disorders.

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