Learning Objectives
- Define and exemplify classification.
- Define nomenclature.
- Define epidemiology.
- Define the presenting problem and clinical description.
- Differentiate prevalence, incidence, and any subtypes.
- Define comorbidity.
- Define etiology.
- Define course.
- Define prognosis.
- Define treatment.
Classification
Classification is not a foreign concept and as a student you have likely taken at least one biology class that discussed the taxonomic classification system of Kingdom, Phylum, Class, Order, Family, Genus, and Species revolutionized by Swedish botanist, Carl Linnaeus. You probably even learned a witty mnemonic such as ‘King Phillip, Come Out For Goodness Sake’ to keep the order straight. The Library of Congress uses classification to organize and arrange their book collections and includes such categories as B – Philosophy, Psychology, and Religion; H – Social Sciences; N – Fine Arts; Q – Science; R – Medicine; and T – Technology.
Simply, classification is how we organize or categorize things. The second author’s wife has been known to color-code her Blu Ray collection by genre, movie title, and release date. It is useful for us to do the same with abnormal behavior, and classification provides us with a nomenclature, or naming system, to structure our understanding of mental disorders in a meaningful way. Of course, we want to learn as much as we can about a given disorder so we can understand its cause, predict its future occurrence, and develop ways to treat it.
Determining Occurrence of a Disorder
Epidemiology is the scientific study of the frequency and causes of diseases and other health-related states in specific populations such as a school, neighborhood, a city, country, and the world. Psychiatric or mental health epidemiology refers to the occurrence of mental disorders in a population. In mental health facilities, we say that a patient presents with a specific problem, or the presenting problem, and we give a clinical description of it, which includes information about the thoughts, feelings, and behaviors that constitute that mental disorder. We also seek to gain information about the occurrence of the disorder, its cause, course, and treatment possibilities.
Occurrence can be investigated in several ways. First, prevalence is the percentage of people in a population that has a mental disorder or can be viewed as the number of cases divided by the total number of people in the sample. For instance, if 20 people out of 100 have bipolar disorder, then the prevalence rate is 20%. Prevalence can be measured in several ways:
- Point prevalence indicates the proportion of a population that has the characteristic at a specific point in time. In other words, it is the number of active cases.
- Period prevalence indicates the proportion of a population that has the characteristic at any point during a given period of time, typically the past year.
- Lifetime prevalence indicates the proportion of a population that has had the characteristic at any time during their lives.
According to a 2020 infographic by the National Alliance on Mental Illness (NAMI), for U.S. adults, 1 in 5 experienced a mental illness, 1 in 20 had a serious mental illness, 1 in 15 experienced both a substance use disorder and mental disorder, and over 12 million had serious thoughts of suicide (2020 Mental Health By the Numbers: US Adults infographic). In terms of adolescents aged 12-17, in 2020 1 in 6 experienced a major depressive episode, 3 million had serious thoughts of suicide, and there was a 31% increase in mental health-related emergency department visits. Among U.S. young adults aged 18-25, 1 in 3 experienced a mental illness, 1 in 10 had a serious mental illness, and 3.8 had serious thoughts of suicide (2020 Mental Health By the Numbers: Youth and Young Adults infographic). These numbers would represent period prevalence rates during the pandemic, and for the year 2020. In the, You are Not Alone infographic, NAMI reported the following 12-month prevalence rates for U.S. Adults: 19% having an anxiety disorder, 8% having depression, 4% having PTSD, 3% having bipolar disorder, and 1% having schizophrenia.
Source: https://www.nami.org/mhstats
Incidence indicates the number of new cases in a population over a specific period. This measure is usually lower since it does not include existing cases as prevalence does. If you wish to know the number of new cases of social phobia during the past year (going from say Aug 21, 2015 to Aug 20, 2016), you would only count cases that began during this time and ignore cases before the start date, even if people are currently afflicted with the mental disorder. Incidence is often studied by medical and public health officials so that causes can be identified, and future cases prevented.
Finally, comorbidity describes when two or more mental disorders are occurring at the same time and in the same person. The National Comorbidity Survey Replication (NCS-R) study conducted by the National Institute of Mental Health (NIMH) and published in the June 6, 2005 issue of the Archives of General Psychiatry, sought to discover trends in prevalence, impairment, and service use during the 1990s. The first study, conducted from 1980 to 1985, surveyed 20,000 people from five different geographical regions in the U.S. A second study followed from 1990-1992 and was called the National Comorbidity Survey (NCS). The third study, the NCS-R, used a new nationally representative sample of the U.S. population, and found that 45% of those with one mental disorder met the diagnostic criteria for two or more disorders. The authors also found that the severity of mental illness, in terms of disability, is strongly related to comorbidity, and that substance use disorders often result from disorders such as anxiety and bipolar disorders. The implications of this are significant as services to treat substance abuse and mental disorders are often separate, despite the disorders appearing together.
Other Key Factors Related to Mental Disorders
The etiology is the cause of the disorder. There may be social, biological, or psychological explanations for the disorder which need to be understood to identify the appropriate treatment. Likewise, the effectiveness of a treatment may give some hint at the cause of the mental disorder. More on this in Module 2.
The course of the disorder is its particular pattern. A disorder may be acute, meaning that it lasts a short time, or chronic, meaning it persists for a long time. It can also be classified as time-limited, meaning that recovery will occur after some time regardless of whether any treatment occurs.
Prognosis is the anticipated course the mental disorder will take. A key factor in determining the course is age, with some disorders presenting differently in childhood than adulthood.
Finally, we will discuss several treatment strategies in this book in relation to specific disorders, and in a general fashion in Module 3. Treatment is any procedure intended to modify abnormal behavior into normal behavior. The person suffering from the mental disorder seeks the assistance of a trained professional to provide some degree of relief over a series of therapy sessions. The trained mental health professional may prescribe medication or utilize psychotherapy to bring about this change. Treatment may be sought from the primary care provider, in an outpatient facility, or through inpatient care or hospitalization at a mental hospital or psychiatric unit of a general hospital. According to NAMI, the average delay between symptom onset and treatment is 11 years with 45% of adults with mental illness, 66% of adults with serious mental illness, and 51% of youth with a mental health condition seeking treatment in a given year. They also report that 50% of white, 49% of lesbian/gay and bisexual, 43% of mixed/multiracial, 34% of Hispanic or Latinx, 33% of black, and 23% of Asian adults with a mental health diagnosis received treatment or counseling in the past year (Source: Mental Health Care Matters infographic, https://www.nami.org/mhstats).
Key Takeaways
You should have learned the following in this section:
- Classification, or how we organize or categorize things, provides us with a nomenclature, or naming system, to structure our understanding of mental disorders in a meaningful way.
- Epidemiology is the scientific study of the frequency and causes of diseases and other health-related states in specific populations.
- Prevalence is the percentage of people in a population that has a mental disorder or can be viewed as the number of cases divided by the total number of people in the sample.
- Incidence indicates the number of new cases in a population over a specific period.
- Comorbidity describes when two or more mental disorders are occurring at the same time and in the same person.
- The etiology is the cause of a disorder while the course is its particular pattern and can be acute, chronic, or time-limited.
- Prognosis is the anticipated course the mental disorder will take.
Review Questions
- What is the importance of classification for the study of mental disorders?
- What information does a clinical description include?
- In what ways is occurrence investigated?
- What is the etiology of a mental illness?
- What is the relationship of course and prognosis to one another?
- What is treatment and who seeks it?
