euphoria. Patients can show aggressive behaviour and these dysfunctions in behaviour can have effects on interpersonal relationships. One explanation of signs of anger and aggression is due to an inability to handle their impulses, this type of aggression being called "impulsive aggression". Diagnosis ICD-11 In the ICD-11, the condition is called secondary personality change rather than organic personality disorder. To meet diagnosis there must be a clinically significant personality disturbance that represents a change from the individual's previous characteristic personality pattern. This personality disturbance must be explainable directly as a result from a pathophysiological health condition affecting the brain. The duration, onset, and remission of the health condition, along with responses to treatment of the underlying health condition, must be consistent with presentations of the personality disturbance. There are seven sub-classifications of secondary personality change based on disturbances of affect, which includes "constricted", "blunted", "flat", "labile" and "inappropriate", along with other specified and unspecified categories. ICD-10 In the ICD-10 there were no specifically listed diagnostic criteria. It is characterized by "a significant alteration of the habitual patterns of behaviour displayed by the subject premorbidly, involving the expression of emotions, needs and impulses." Cognition, thought functions and sexuality are mentioned as potentially altered or affected. Two "organic" and three "syndrome" underlying causes are mentioned respectively: "pseudopsychopathic personality", "pseudoretarded personality", "frontal lobe damage", "limbic epilepsy personality" and post-lobotomy. Differential diagnosis Being an organic disorder, differential diagnosis between mental disorders and OPD is necessary. According to the ICD-11, specific considerations for differential diagnosis include delerium, dementia, personality disorders, impulse control disorder, and addictive behavior syndrome. For differential diagnosis in the ICD-10, along with personality disorders, there are two mentioned conditions in the ICD-10 under the same diagnostic category "F07" for consideration: postencephalitic parkinsonism (called "postencephalitic syndrome" in the ICD-10) and post-concussion syndrome. Patients with OPD may present similar symptoms to Huntington's disease. The symptoms of apathy and irritability are common between these two conditions. OPD is somewhat similar to temporal lobe epilepsy, as patients who have chronic epilepsy may also express aggressive behaviours. Another similar symptom between Temporal lobe epilepsy and OPD is epileptic seizures. The symptom of epileptic seizure has influence on patients' personality that means it causes behavioural alterations. Temporal lobe epilepsy is associated with the hyperexcitability of the medial temporal lobe of patients. Treatment Patients with OPD show a wide variety of sudden behavioural changes and dysfunctions. There is little