"Obsessions are unwanted, intrusive thoughts, images, or urges that trigger intensely distressing feelings," according to the International OCD Foundation. "Compulsions are behaviors an individual engages in to attempt to get rid of the obsession and/or decrease his or her distress."
A person with OCD cannot stop or control their obsessions or the compulsions they engage in to try to reduce the anxiety caused by the obsessions. OCD can be very disruptive and disturbing in everyday life, and can impact personal and professional relationships and tasks.
In the 17th century, obsessions and compulsions were tied to straying from the proper religious path, symptomatic of "religious melancholy" or "naughty, and sometimes blasphemous thoughts," according to Stanford University School of Medicine. The concept and terminology of OCD evolved in the centuries since, with Stanford noting for the future:
As the twenty-first century begins, advances in pharmacology, neuroanatomy, neurophysiology and learning theory have allowed us to reach a more therapeutically useful conceptualization of OCD. Although the causes of the disorder still elude us, the recent identification of children with OCD caused by an autoimmune response to group A beta-hemolytic streptococcal infection promises to bring increased understanding of the disorder's pathogenesis.