Hello Thanks for asking Dementia Pugilistica also called as chronic traumatic encephalopathy is a type of dementia that occur in boxers after repeated trauma on head. The main clinical features are declining memory and features of Parkinson s disease like tremors and a number of other symptoms. He is having forgetfulness but no other symptoms are there that can label him with dementia pugilistica. Multiple trauma to head and then one serious accident are most likely the reason for his personality change. He is acting stranger, have problems of aggression, don t listen any one and has started taking alcohol. He is not remembering the episode of aggression. Such symptoms may occur some time following head trauma because of injury to frontal and temporal lobe of brain. Injury to brain may cause personality changes and may aggravate anti-social behaviour. Loss of short term memory might be due to trauma only. I would advise you to consult a good Psychiatrist for his treatment. To decrease his aggression and post traumatic complications medicines like Mood Stabilisers like Sodium Valproate, Carbamazepine etc can be used. Hope this helps you, thanks