Like other types of scientific inquiry, our understanding of personality disorders has evolved over time. The various classification systems used to diagnose and describe personality disorders, during different periods of history, were bounded by the knowledge, social attitudes, and the scientific paradigms available during the historical period in which they were conceived. An understanding of this historical context strengthens our ability to fully appreciate the research advancements that have informed our current understanding of these disorders. These scientific advancements subsequently guided the development of successful treatment approaches.
Writing during the 4th century BC, Hippocrates described all disease as an imbalance of the four bodily humors. The basic idea was that there were four fluids in the body; namely, phlegm, blood, yellow bile, and black bile. Variations in the levels of these fluids were believed to be connected to changes in people's moods.
Much later, in the 18th century, Philippe Pinel observed there were a group of patients who behaved in irrational ways even though they seemed to be in touch with reality and were aware of the irrationality of their actions. Pinel's documented observations during this period appear to be one of the first explicit attempts at describing what we would nowadays call a personality disorder.
By the early 1900s, European diagnostic systems were beginning to describe different temperaments and personality types. At this point in history, mental conditions and disorders were not very well defined because the scientific professions of psychology and psychiatry were still in their infancy. Most psychiatrists were purely focused on describing the phenomena of mental illness and disturbances they observed. From these early descriptions we can determine that much of what was observed and described would today be considered a personality disorder. However, at that time, the symptoms that were observed were thought to be something else, namely the early stages of some other, more severe mental illnesses such as manic depression (now called Bipolar Disorder).
During the 1920's and 30's Sigmund Freud and his colleagues were one of the first to move beyond mere descriptive categorization of mental disorders. Instead, Freud and his camp theorized the etiology (causes) of behavioral and emotional problems. Although our modern understanding of personality disorders has advanced significantly beyond these earlier theories of Sigmund Freud, he is still often credited as the “father of psychology.”
Freud and his followers began to theorize how character types and emotional issues developed. Freud's theory proposed the existence of unconscious mental processes that influence our character development and subsequent behavior. He explained these unconscious mental processes as consisting of three competing component parts. He named these three parts the Id, the Ego, and the Superego. The Id referred to a collection of instinctual impulses and drives, seeking immediate gratification. The Superego referred to a set of moral values and self-critical attitudes. The term "Ego" was used to describe a set of regulatory functions intended to keep the Id under control by preventing the Id from indulging its every whim. The Ego's purpose was to mediate a balance between the impulsive Id and the harsh, moralistic Superego. In Freudian theory, the goals of these three mental components were in conflict with each other, causing anxiety. The Ego relied on "defense mechanisms" to keep such conflicts from entering our conscious awareness so as to reduce this anxiety.
Freud and his colleagues were also interested in exploring infantile sexual development. It was theorized that we are born with the Id, so that every infant has the inborn raw impulses that seek immediate gratification. Over time, the Ego develops and keeps the Id in check, trying to keep the person anchored in reality. The Superego consisted of moral values and harbored a concept of an ideal self. It was thought to develop last. The psychoanalysts (as followers of Freud's theory and his methods came to be known) believed that during childhood, we undergo different stages of psychosexual maturation. Frustrations, or conversely overindulgences, experienced during particular stages of development, could cause a person to become stuck, or "fixated" at that particular developmental stage. This fixation interfered with the proper and timely development of the Ego or Superego. As a result, the normal and appropriate Ego balance of Id and Superego energies could not be achieved. Some psychoanalysts viewed personality disorders (or "character disorders" as they were once called) as fixations that emerged during early developmental stages. At this point in history, character disorders were considered to be difficult to treat and quite resistant to change.