According to the World Health Organization, a mental disorder is a condition that involves disturbances in thinking, emotions, or behavior that impact or challenge daily functioning (World Health Organization [WHO], 2022). As used in our text, the term mental disorder encompasses mental illnesses, substance use disorders, and developmental disorders, all of which are discussed in this chapter. Mental disorders can affect how we understand the world, relate to others, and make choices (Substance Abuse and Mental Health Services Administration [SAMHSA], 2023a). It is estimated that one in five adults in the United States experiences a mental disorder (National Alliance on Mental Illness [NAMI], n.d.-a).

Some mental disorders are quite rare, while others are common. Some involve a single episode, while others are likely to recur; still others are lifelong conditions that exist from birth or early childhood. The symptoms of mental disorders may fall anywhere on a spectrum from mild to very serious. The descriptor of a serious mental illness refers to a small subset of mental disorders: mental illnesses with symptoms that substantially impact major life activities. Some of the disorders described in this chapter, such as schizophrenia, are typically considered serious mental illnesses (SAMHSA, 2023b).

Diagnosing Mental Disorders

A first step in understanding mental disorders is appreciating how mental health professionals determine whether a person has a mental disorder. Those professionals must identify and label sets of symptoms to determine if a mental disorder is present and to arrive at the right diagnosis, or name, for that disorder. The diagnostic process enables people to use a common language when discussing mental disorders, and it guides the way for professionals to determine effective treatments. For these reasons, classification systems that systematically organize mental disorders are necessary.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is one such classification system, and it is the one used by most mental health professionals in the United States. The DSM describes numerous categories of disorders (e.g., anxiety disorders) and then lists particular disorders within each category (e.g., general anxiety, social anxiety). Listed disorders in a category are described in detail with criteria, or specific elements, that allow a person to be diagnosed with that disorder. Diagnostic criteria typically include the symptoms that are experienced or observed (e.g., agitation, difficulty sleeping) and the length of time (e.g., minimum six months) these symptoms must continue to qualify for a particular diagnosis.

The first edition of the DSM was published by the American Psychiatric Association in 1952, and it has undergone numerous revisions and editions as indicated by the numbers in the title: the DSM-3, DSM-4, and so on. In 2022, the most recent revision resulted in the publication of the DSM-5-TR, an updated “text revision” of the DSM-5 (figure 2.2) (American Psychiatric Association, 2024a). Information from the 2022 version is used in this text.

Each new edition of the DSM reflects changes to the understanding and management of mental disorders. Updates include adding new diagnoses and removing others, as well as reorganization of categories. Over time, the details and descriptions of diagnoses have expanded. Some changes demonstrate evolving social perspectives. For example, being gay was considered a disorder in the original DSM scheme, and it was not until several revisions later, in 1987, that this was fully removed. The recent DSM-5-TR underwent multiple equity-focused reviews to help bring it into the modern age. Committees focused on culture and gender issues and a workgroup on ethnoracial equity were tasked with looking at problems such as racism and stigmatizing language (American Psychiatric Association, 2024a). Some positive results are evident in the latest version, such as the modification of gender-focused language, which resulted in the terms experienced gender and gender-affirming medical procedure replacing outdated and stigmatizing terms. Nevertheless, it is widely acknowledged that more work needs to be done in terms of guiding safe and effective diagnostic approaches for people of color and other marginalized groups (White, 2022).

Caring for People with Mental Disorders

Throughout this chapter, specific mental disorders are identified and briefly described, including mention of treatments available to help impacted individuals. Because mental disorders can arise from many causes—biology, childhood experience, sociocultural factors—there are many different treatment approaches for problems that may arise from them (Spielman et al., 2020a). Seeking treatment for mental disorders can be confusing and daunting, as pursuing help often requires navigating options as well as facing stigma (figure 2.3) (Spielman et al., 2020a).

While many effective treatments for mental disorders do exist, most people with mental disorders ultimately lack access to these options (WHO, 2022). Even when treatments are available generally, they may not be properly tailored to the person who needs them. A person’s identity and culture impact how the person will experience a mental disorder and what supports will work best to help (NAMI, 2024a). Care that factors in and positively uses understanding of a person’s background and life experiences is considered culturally competent care. A care provider who recognizes and engages in the ongoing process of learning about and respecting others’ cultures, including examining the provider’s own biases, would be exhibiting the related value of cultural humility (Fountain House, n.d.). Cultural considerations are critical to proper care for many who experience mental disorders, yet they are too often lacking.

Individuals in Indigenous/Native communities in the United States, for example, have significant rates of mental disorders that are understood to be related to generations of trauma from violence, displacement, and destruction of their culture when their land was colonized by Europeans. Yet, critical mental health care is drastically weakened for these communities due to several factors, including lack of proper funding, geographical isolation, language barriers (words like “depressed” do not have ready translations in some Native languages), and understandable community mistrust of government. Compounding these barriers is a general lack of cultural competence to serve this group adequately and difficulties in providing training to correct that problem (NAMI, 2024a).

Throughout this text, we will be considering how the criminal justice system is intertwined with deficits in care for people with mental disorders. Certainly, a lack of effective care is a critical factor that leads many people with mental disorders into contact with the criminal justice system and causes that contact to be sustained (SAMHSA, 2022a).

Licenses and Attributions for Identification and Treatment of Mental Disorders

Open Content, Original

“Identification and Treatment of Mental Disorders” by Anne Nichol is licensed under CC BY 4.0.

“Caring for People with Mental Disorders” by Anne Nichol is licensed under CC BY 4.0.

Open Content, Shared Previously

“Diagnosing Mental Disorders” by Kendra Harding is adapted from “15.2 Diagnosing and Classifying Psychological Disorders” by by Rose M. Spielman, William J. Jenkins, and Marilyn D. Lovett, Psychology 2e, Openstax, which is licensed under CC BY 4.0. Modifications by Anne Nichol, licensed under CC BY 4.0, include significantly revising and expanding the content.

Figure 2.2. “The DSM-5-TR” by the American Psychiatric Association is in the public domain.

Figure 2.3. “Brittany Brooks, MD, speaks with a patient” by Nina Robinson/Getty Images/Images of Empowerment is licensed under CC BY 4.0.