Concern regarding my 19 year old brother

My brother is 19 years old. We have noticed the following behavioural concerns: * He is very aggressive in normal day-to-day conversations. * His facial expressions and behaviour change noticeably when he gets angry. * He often brings up incidents from 5–6 years ago and becomes excessively angry about them. * He seems unable to let go of past issues and holds resentment. * He has difficulty maintaining friendships and mostly interacts with family. * He can be very defensive and finds it difficult to accept when he is wrong. * Sometimes he says he feels depressed. * He makes statements like, “I could have become an engineer, doctor, or whatever I wanted.” We would like to understand if there could be an underlying mental health concern This has been happening from last 2 years and as family we are being in lot of stress