Mental Health Issues for people 18 years and older

Often times people are mentally unstable and is incapable of making there own desicions as an adult. Here in Oregon your considered an adult at just 18 years old. There is often times the mentally challenged adults are turned away from recieving the help they need because of there age. I'm one of those parents who has no legal right to what's going on with ny 21 year old daughter. She's homeless, suicidal, has mental health illnesses and in danger, no ones willing to help me and my child. I'm not just speaking for me and my daughter, but being a voice, and advocate for all those who are mentally challenged who's 18 and older.