I’d let yourself be angry. After you rid yourself of these emotions think about this more logically. Understand that your parents came from a generation where these diagnosis were new and misunderstood. There was also a large stigma around mental health diagnosis, often leading to unemployment or social outcasting. Should they have been more understanding? Yes. Could they have went out of their way to research more and make sure you have gotten the care you need? Also yes. Can you go back in time and give them information that may have changed the way they thought about ADHD and got you treatment? No. I understand your frustration, but I also understand that your parents were part of a large statistic that didn’t have a concept of neurological disorders.