(c) : Borderline personality disorder $(BPD)$ is a serious mental illness characterized by pervasive instability in moods, interpersonal relationships, self­ image, and behaviour. This instability often disrupts family and work life, long­term planning, and the individual’s sense of self­identity. Originally thought to be at the “borderline” of psychosis, people with $BPD$ suffer from a disorder of emotion regulation. Schizophrenia is a group of severe mental disorders characterized by disturbances of language and communication; thought disturbances that may involve distortion of reality, misperceptions, delusions and hallucinations; mood changes and withdrawn, regressive, or bizarre behaviour, lasting longer than six months. A mood disorder is a condition where the prevailing emotional mood is distorted or inappropriate to the circumstances. Addiction is a state of dependence produced by the habitual taking of drugs, alcohol etc.