Usage Note: The word neurosis has been used since the 1700s, when it referred broadly to a "nervous disease." With the advent of Freud's theory of psychoanalysis in the late 1800s, neurosis evolved to refer to mental disorders resulting from internal psychological conflicts rather than from neurological diseases or conditions. Today, the words neurosis and neurotic are no longer used in formal psychiatric diagnosis. The conditions formerly referred to as neurotic are now described with many other terms, such as anxiety disorder, obsessive-compulsive disorder, and post-traumatic stress disorder. Neurosis and neurotic are still frequently used in informal conversation and writing to denote recurrent worry and anxiety.