The prevalence of mental disorders has been studied around the world, providing estimates on how common mental disorders are. Different criteria or thresholds of severity have sometimes been used.
National and international figures are typically estimated by large-scale surveys of self-reported symptoms up to the time of assessment; sometimes a figure is calculated for the occurrence of disorder in the week, month or year prior to assessment–a point or period prevalence; sometimes the figure is for a person's lifetime prior to assessment–the so-called lifetime prevalence.
Numerous large-scale surveys of the prevalence of mental disorders in adults in the general population have been carried out since the 1980s based on self-reported symptoms assessed by standardized structured interviews, usually carried out over the phone.
Mental disorders have been found to be common, with over a third of people in most countries reporting sufficient criteria to be diagnosed at some point in their life. [1] The World Health Organization (WHO) reported in 2001 that about 450 million people worldwide have some form of mental disorder or brain condition, and that one in four people meet criteria at some point in their life. [2] [3] [4]
The World Health Organization is currently[ when? ] undertaking a global survey of 26 countries in all regions of the world, based on ICD and DSM criteria. [5] The first published figures on the 14 country surveys completed to date, indicate that, of those disorders assessed, anxiety disorders are the most common in all but 1 country (prevalence in the prior 12-month period of 2.4% to 18.2%) and mood disorders next most common in all but 2 countries (12-month prevalence of 0.8% to 9.6%), while substance disorders (0.1–6.4%) and impulse-control disorders (0.0–6.8%) were consistently less prevalent. [6]
The United States, Colombia, the Netherlands and Ukraine tended to have higher prevalence estimates across most classes of disorder, while Nigeria, Shanghai and Italy were consistently low, and prevalence was lower in Asian countries in general. Cases of disorder were rated as mild (prevalence of 1.8–9.7%), moderate (prevalence of 0.5–9.4%) and serious (prevalence of 0.4–7.7%). [6]
The World Health Organization has published worldwide incidence and prevalence estimates of individual disorders. Obsessive-compulsive disorder is two to three times as common in Latin America, Africa, and Europe as in Asia and Oceania. [7] Schizophrenia appears to be most common in Japan, Oceania, and Southeastern Europe and least common in Africa. [8] Bipolar disorder and panic disorder have very similar rates around the world. [9] [10]
However, these are widely believed to be underestimates, due to poor diagnosis (especially in countries without affordable access to mental health services) and low reporting rates, in part because of the predominant use of self-report data, rather than semi-structured instruments such as the Structured Clinical Interview for DSM-IV (SCID); actual lifetime prevalence rates for mental disorders are estimated to be between 65% and 85%.[ citation needed ] [8]
Previous widely cited large-scale surveys in the US were the Epidemiological Catchment Area (ECA) survey and subsequent National Comorbidity Survey (NCS). [11] The NCS was replicated and updated between 2000 and 2003 and indicated that, of those groups of disorders assessed, nearly half of Americans (46.4%) reported meeting criteria at some point in their life for either a DSM-IV anxiety disorder (28.8%), mood disorder (20.8%), impulse-control disorder (24.8%) or substance use disorders (14.6%). Half of all lifetime cases had started by age 14 and three quarters by age 24. [12]
In the prior 12-month period only, around a quarter (26.2%) met criteria for any disorder—anxiety disorders 18.1%; mood disorders 9.5%; impulse control disorders 8.9%; and substance use disorders 3.8%. A substantial minority (23%) met criteria for more than two disorders. 22.3% of cases were classed as serious, 37.3% as moderate and 40.4% as mild. [13] [14]
A 2004 cross-European study found that approximately one in four people reported meeting criteria at some point in their life for one of the DSM-IV disorders assessed, which included mood disorders (13.9%), anxiety disorders (13.6%) or alcohol disorder (5.2%). Approximately one in ten met criteria within a 12-month period. Women and younger people of either gender showed more cases of disorder. [15]
A 2005 review of 27 studies have found that 27% of adult Europeans is or has been affected by at least one mental disorder in the past 12 months. It was also found that the most frequent disorders were anxiety disorders, depressive, somatoform and substance dependence disorders. [16]
A review that pooled surveys in different countries up to 2004 found overall average prevalence estimates for any anxiety disorder of 10.6% (in the 12 months prior to assessment) and 16.6% (in lifetime prior to assessment), but that rates for individual disorders varied widely. Women had generally higher prevalence rates than men, but the magnitude of the difference varied. [17]
A review that pooled surveys of mood disorders in different countries up to 2000 found 12-month prevalence rates of 4.1% for major depressive disorder (MDD), 2% for dysthymic disorder and 0.72% for bipolar 1 disorder. The average lifetime prevalence found was 6.7% for MDD (with a relatively low lifetime prevalence rate in higher-quality studies, compared to the rates typically highlighted of 5–12% for men and 10–25% for women), and rates of 3.6% for dysthymia and 0.8% for Bipolar 1. [18] Certain population subgroups, such as physicians in training, have 12-month prevalence rates as high as 21 to 43%. [19] [20] [21]
A 2005 review of prior surveys in 46 countries on the prevalence of schizophrenic disorders, including a prior 10-country WHO survey, found an average (median) figure of 0.4% for lifetime prevalence up to the point of assessment and 0.3% in the 12-month period prior to assessment. A related figure not given in other studies (known as lifetime morbid risk), reported to be an accurate statement of how many people would theoretically develop schizophrenia at any point in life regardless of time of assessment, was found to be "about seven to eight individuals per 1,000" (0.7/0.8%). The prevalence of schizophrenia was consistently lower in poorer countries than in richer countries (though not the incidence), but the prevalence did not differ between urban/rural areas or men/women (although incidence did). [22]
Studies of the prevalence of personality disorders (PDs) have been fewer and smaller-scale, but a broader Norwegian survey found a similar overall prevalence of almost 1 in 7 (13.4%), based on meeting personality criteria over the prior five-year period. Rates for specific disorders ranged from 0.8% to 2.8%, with rates differing across countries, and by gender, educational level and other factors. [23] A US survey that incidentally screened for personality disorder found an overall rate of 14.79%. [24]
Approximately 7% of a preschool pediatric sample were given a psychiatric diagnosis in one clinical study, and approximately 10% of 1- and 2-year-olds receiving developmental screening have been assessed as having significant emotional/behavioral problems based on parent and pediatrician reports. [25]
Bipolar disorder, previously known as manic depression or manic depressive disorder, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that each last from days to weeks. If the elevated mood is severe or associated with psychosis, it is called mania; if it is less severe and does not significantly affect functioning, it is called hypomania. During mania, an individual behaves or feels abnormally energetic, happy, or irritable, and they often make impulsive decisions with little regard for the consequences; there is usually also a reduced need for sleep during manic phases. During periods of depression, the individual may experience crying, have a negative outlook on life, and demonstrate poor eye contact with others. The risk of suicide is high; over a period of 20 years, 6% of those with bipolar disorder died by suicide, while 30–40% engaged in self-harm. Other mental health issues, such as anxiety disorders and substance use disorders, are commonly associated with bipolar disorder. The global prevalence of bipolar disorder is estimated to be between 1-5% of the world's popluation.
Bipolar I disorder is a type of bipolar spectrum disorder characterized by the occurrence of at least one manic episode, with or without mixed or psychotic features. Most people also, at other times, have one or more depressive episodes. Typically, these manic episodes can last at least 7 days for most of each day to the extent that the individual may need medical attention, while the depressive episodes last at least 2 weeks.
The Diagnostic and Statistical Manual of Mental Disorders is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common language and standard criteria. It is an internationally accepted manual on the diagnosis and treatment of mental disorders, though it may be used in conjunction with other documents. Other commonly used principal guides of psychiatry include the International Classification of Diseases (ICD), Chinese Classification of Mental Disorders (CCMD), and the Psychodynamic Diagnostic Manual. However, not all providers rely on the DSM-5 as a guide, since the ICD's mental disorder diagnoses are used around the world, and scientific studies often measure changes in symptom scale scores rather than changes in DSM-5 criteria to determine the real-world effects of mental health interventions.
A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is also characterized by a clinically significant disturbance in an individual's cognition, emotional regulation, or behavior, often in a social context. Such disturbances may occur as single episodes, may be persistent, or may be relapsing–remitting. There are many different types of mental disorders, with signs and symptoms that vary widely between specific disorders. A mental disorder is one aspect of mental health.
A mood disorder, also known as an affective disorder, is any of a group of conditions of mental and behavioral disorder where the main underlying characteristic is a disturbance in the person's mood. The classification is in the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD).
Anxiety disorders are a group of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal functions are significantly impaired. Anxiety may cause physical and cognitive symptoms, such as restlessness, irritability, easy fatigue, difficulty concentrating, increased heart rate, chest pain, abdominal pain, and a variety of other symptoms that may vary based on the individual.
Schizoaffective disorder is a mental disorder characterized by symptoms of both schizophrenia (psychosis) and a mood disorder - either bipolar disorder or depression. The main diagnostic criterion is the presence of psychotic symptoms for at least two weeks without prominent mood symptoms. Common symptoms include hallucinations, delusions, disorganized speech and thinking, as well as mood episodes. Schizoaffective disorder can often be misdiagnosed when the correct diagnosis may be psychotic depression, bipolar I disorder, schizophreniform disorder, or schizophrenia. This is a problem as treatment and prognosis differ greatly for most of these diagnoses. Many people with schizoaffective disorder have other mental disorders including anxiety disorders.
Obsessive–compulsive personality disorder (OCPD) is a cluster C personality disorder marked by a spectrum of obsessions with rules, lists, schedules, and order, among other things. Symptoms are usually present by the time a person reaches adulthood, and are visible in a variety of situations. The cause of OCPD is thought to involve a combination of genetic and environmental factors, namely problems with attachment.
Generalized anxiety disorder (GAD) is a mental and behavioral disorder, specifically an anxiety disorder characterized by excessive, uncontrollable and often irrational worry about events or activities. Worry often interferes with daily functioning, and individuals with GAD are often overly concerned about everyday matters such as health, finances, death, family, relationship concerns, or work difficulties. Symptoms may include excessive worry, restlessness, trouble sleeping, exhaustion, irritability, sweating, and trembling.
Intermittent explosive disorder is a behavioral disorder characterized by explosive outbursts of anger and/or violence, often to the point of rage, that are disproportionate to the situation at hand. Impulsive aggression is not premeditated, and is defined by a disproportionate reaction to any provocation, real or perceived. Some individuals have reported affective changes prior to an outburst, such as tension, mood changes, energy changes, etc.
Postpartum blues, also known as baby blues and maternity blues, is a very common but self-limited condition that begins shortly after childbirth and can present with a variety of symptoms such as mood swings, irritability, and tearfulness. Mothers may experience negative mood symptoms mixed with intense periods of joy. Up to 85% of new mothers are affected by postpartum blues, with symptoms starting within a few days after childbirth and lasting up to two weeks in duration. Treatment is supportive, including ensuring adequate sleep and emotional support. If symptoms are severe enough to affect daily functioning or last longer than two weeks, the individual should be evaluated for related postpartum psychiatric conditions, such as postpartum depression and postpartum anxiety. It is unclear whether the condition can be prevented, however education and reassurance are important to help alleviate patient distress.
Bipolar disorder in children, or pediatric bipolar disorder (PBD), is a rare mental disorder in children and adolescents. The diagnosis of bipolar disorder in children has been heavily debated for many reasons including the potential harmful effects of adult bipolar medication use for children. PBD is similar to bipolar disorder (BD) in adults, and has been proposed as an explanation for periods of extreme shifts in mood called mood episodes. These shifts alternate between periods of depressed or irritable moods and periods of abnormally elevated moods called manic or hypomanic episodes. Mixed mood episodes can occur when a child or adolescent with PBD experiences depressive and manic symptoms simultaneously. Mood episodes of children and adolescents with PBD are different from general shifts in mood experienced by children and adolescents because mood episodes last for long periods of time and cause severe disruptions to an individual's life. There are three known forms of PBD: Bipolar I, Bipolar II, and Bipolar Not Otherwise Specified (NOS). The average age of onset of PBD remains unclear, but reported age of onset ranges from 5 years of age to 19 years of age. PBD is typically more severe and has a poorer prognosis than bipolar disorder with onset in late-adolescence or adulthood.
Dual diagnosis is the condition of having a mental illness and a comorbid substance use disorder. There is considerable debate surrounding the appropriateness of using a single category for a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcohol use disorder, or it can be restricted to specify severe mental illness and substance use disorder, or a person who has a milder mental illness and a drug dependency, such as panic disorder or generalized anxiety disorder and is dependent on opioids. Diagnosing a primary psychiatric illness in people who use substances is challenging as substance use disorder itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness.
Bipolar II disorder (BP-II) is a mood disorder on the bipolar spectrum, characterized by at least one episode of hypomania and at least one episode of major depression. Diagnosis for BP-II requires that the individual must never have experienced a full manic episode. Otherwise, one manic episode meets the criteria for bipolar I disorder (BP-I).
Cannabis use disorder (CUD), also known as cannabis addiction or marijuana addiction, is a psychiatric disorder defined in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and ICD-10 as the continued use of cannabis despite clinically significant impairment.
The World Health Organization Composite International Diagnostic Interview (CIDI) is a structured interview for psychiatric disorders. As the interview is designed for epidemiological studies, it can be administered by those who are not clinically trained and can be completed in a short amount of time. Versions of the CIDI were used in two important studies, the National Comorbidity Survey (NCS) and National Comorbidity Survey Replication (NCS-R) which are often used as a reference for estimates of the rates of psychiatric illness in the USA. The first version of the CIDI was published in 1988, and has been periodically updated to reflect the changing diagnostic criteria of DSM and ICD.
The diagnosis of schizophrenia, a psychotic disorder, is based on criteria in either the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, or the World Health Organization's International Classification of Diseases (ICD). Clinical assessment of schizophrenia is carried out by a mental health professional based on observed behavior, reported experiences, and reports of others familiar with the person. Diagnosis is usually made by a psychiatrist. Associated symptoms occur along a continuum in the population and must reach a certain severity and level of impairment before a diagnosis is made. Schizophrenia has a prevalence rate of 0.3-0.7% in the United States.
Schizophrenia affects around 0.3–0.7% of the general population at some point in life, or 21 million people worldwide as of 2020. By using precise methods in its diagnosis and a large, representative population, schizophrenia seems to occur with relative consistency over time during the last half-century.
The epidemiology of depression has been studied across the world. Depression is a major cause of morbidity and mortality worldwide, as the epidemiology has shown. Lifetime prevalence estimates vary widely, from 3% in Japan to 17% in India. Epidemiological data shows higher rates of depression in the Middle East, North Africa, South Asia and the United States than in other regions and countries. For most countries among the 10 studied, the number of people who experience depression during their lifetimes falls within an 8–12% range.
Disruptive mood dysregulation disorder (DMDD) is a mental disorder in children and adolescents characterized by a persistently irritable or angry mood and frequent temper outbursts that are disproportionate to the situation and significantly more severe than the typical reaction of same-aged peers. DMDD was added to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as a type of depressive disorder diagnosis for youths. The symptoms of DMDD resemble many other disorders, thus a differential includes attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), anxiety disorders, and childhood bipolar disorder, intermittent explosive disorder (IED), major depressive disorder (MDD), and conduct disorder.