The origins of psychiatric interest, in what are now described as personality disorders, were limited to those who were deemed sane but also showed an absence of conscience and a lack of consideration for the rights of others.What is your personality?This highlights a problem for any system of diagnosis, which operates using the digital rule of present/absent or ordered/disordered.The total absence of measured blood pressure is a symptom of being dead and so blood pressure can only be described meaningfully for live subjects on a continuum rather than as a category.Similarly, personality is a description of live subjects and so has to be described in relative rather than categorical terms.If personality disorder were defined by personality characteristics from academic psychology, then a computation of five different scores on the personality dimensions would need to be measured.Currently, the diagnosis is not made using this method and no professional agreement exists on this method of case identification.For example, the general population contains about one per cent of people warranting the label but others have that tendency to some degree.Are psychologists and psychiatrists talking about personality traits in the same way?Thus a clear epistemological gap seems to exist between psychiatric and psychological conceptualisations of personality.Can personality disorder be distinguished from other forms of mental disorder?For any diagnosis to be valid, it should be coherent and separate from other conditions.Not only are these types of personality disorder not distinguishable from neurosis, they are also fundamentally constituted by it.Is the diagnosis of personality disorder used consistently?This is known as the problem of reliability of diagnosis, which takes two forms.This is more important in the diagnosis of personality disorder than of illness, because the latter may change with remission or recovery.Because personality disorder is about enduring personal qualities, then we would expect stability of scores.Can personality disorder be readily differentiated from normality?The problem this question highlights is that the qualities described as personality disordered may lead to good social adjustment or significant success in some social contexts.The aggressive propensities of the psychopath may be expressed lucratively in a professional boxer or honourably in a soldier.A narcissist might find an esteemed career in political life or success in the leadership of a large organisation.The passivity and dependency of some Asian and Arctic cultures may mirror many of the symptoms of dependent personality disorder.The dramatic and flamboyant norms of Mediterranean countries may mirror many of the symptoms of histrionic personality disorder.Can the aetiology of personality disorder be specified?No. The validity of a medical diagnosis requires a clear aetiology.However, personality disorder shares this vulnerability with the diagnosis of functional mental illness.All functional diagnoses are defined in a circular way, rather than by aetiology.How we know this patient suffers from borderline personality disorder?Why do they behave in this way?Because they suffer from borderline personality disorder.Can personality disorder be treated?This awkward question persists.The short answer is that the consequences of the disorder may be mitigated but the underlying personality cannot.And even when efforts have been made to change the social consequences of personality disorder, the results are not clear.Change in individual patients is often slow, faltering and difficult to demonstrate over long periods of time.A final point to make about personality disorder for emphasis is that it is basically a medical codification of people who recurrently act in a way that others disapprove of, condemn or find tiresome.The diagnosis is a way of expressing dislike, disgust or contempt for others.The term moral insanity still has resonances today.The diagnosis of personality disorder is still about moral attributions.However, it can be thought of as a continuum between everyday obsessions with ones own body and completed suicide.The wider implications for human acts of aggression against the self are discussed.Questions for all of us to answer about these wider implications are posed.Examples here would be of people deliberately cutting or burning themselves or swallowing sharp objects.A range of views exists within this narrow focus about what should be done from the coercive prevention of such acts to simple tolerance and the provision of hygienic first aid.In between lie various approaches to its treatment, including addressing the underlying reasons for the action.Obsessive behaviour about ones own body is commonplace.Examples of this would be scratching, knuckle cracking, nail biting, hair twisting and plucking, lip chewing, skin picking and teeth grinding.A common recent example is the fashion for piercing and tattooing, both of which require painful insertions of sharp objects into healthy skin.The less dramatic example in religious devotion is fasting, which deliberately invokes hunger pangs.All the major deistic faiths place a positive value on fasting.However, the difficult experiential distinction between pleasure and pain is highlighted by sadomasochism.This overall experience is positively enjoyed by its participants.However, risk to self in males may manifest itself more indirectly because of their greater proneness to substance use, fighting and fast driving.In particular, they focus on the way in which pain is a positive alternative to inner emptiness.In psychodynamic terms, this would be framed more as a schizoid rather than as a depressive phenomenon.Also, whether motivated by aggression or meaning, there are victims other than those physically injured.Harm to the self can bring distress to others too.Can its rational and irrational aspects be readily distinguished?Can turning against the self be readily distinguished from turning against others?What is the relationship between pain and pleasure?These questions take us well beyond the narrow group of medical and psychiatric patients introduced at the beginning of this entry.The use of a psychoactive substance in a way that causes harm to the self or others.Substance misuse is described, mainly using alcohol abuse as an example.The public health as well as individual consequences of substance misuse are discussed.