What you’ll learn to do: define psychological disorders and explain how they are classified

Psychological disorders are conditions characterized by abnormal thoughts, feelings, and behaviors. Although challenging, it is essential for psychologists and mental health professionals to agree on what experiences and actions constitute the presence of a psychological disorder. Inner experiences and behaviors that are atypical or violate social norms could signify the presence of a disorder; however, each of these criteria alone is inadequate. It is generally accepted that a psychological disorder is defined by significant disturbances in thoughts, feelings, and behaviors; these disturbances must reflect some kind of dysfunction (biological, psychological, or developmental), must cause significant impairment in one’s life, and must not reflect culturally expected reactions to certain life events.

In this section, you’ll learn about how disorders are defined, and also how they are diagnosed and classified. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is essentially a classification manual that clinicians can use to read about the criteria, prevalence, risk factors, and details about 200 disorders.