This statistic has been supported by other studies in the US, with overall global prevalence statistics ranging from 9% to 11%.A UK national epidemiological study (based on DSM-IV screening criteria), reclassified into levels of severity rather than just diagnosis, reported in 2010 that the majority of people show some personality difficulties in one way or another (short of threshold for diagnosis), while the prevalence of the most complex and severe cases (including meeting criteria for multiple diagnoses in different clusters) was estimated at 1.3%. Even low levels of personality symptoms were associated with functional problems, but the most severely in need of services was a much smaller group.Personality disorders (especially Cluster A) are found more commonly among homeless people.There are some sex differences in the frequency of personality disorders which are shown in the table below. : 206  The known prevalence of some personality disorders, especially borderline PD and antisocial PD are affected by diagnostic bias. This is due to many factors including disproportionately high research towards borderline PD and antisocial PD, alongside social and gender stereotypes, and the relationship between diagnosis rates and prevalence rates. Since the removal of depressive PD, self-defeating PD, sadistic PD and passive-aggressive PD from the DSM-5, studies analysing their prevalence and demographics have been limited. History
Diagnostic and Statistical Manual history
Before the 20th century
Personality disorder is a term with a distinctly modern meaning, owing in part to its clinical usage and the institutional character of modern psychiatry.
Halogen compounds
Iodides of selenium are not well known. The only stable chloride is selenium monochloride (Se2Cl2), which might be better known as selenium(I) chloride; the corresponding bromide is also known. These species are structurally analogous to the corresponding disulfur dichloride. Selenium dichloride is an important reagent in the preparation of selenium compounds (e.g. the preparation of Se7). It is prepared by treating selenium with sulfuryl chloride (SO2Cl2).