Nope..once your child turns 18, they are legally an adult and responsible for their own decisions and actions. Unfortunately, some people just cant accept the responsibility of their own actions. However, if Britney does have a diagnosed mental illness, her parents can file an order in court for her to be placed in a facility where she can get the help she needed. Regardless of that, the end result is until the person is willing to accept help, there is really nothing anyone can do but to continue to show their love and support with the understanding of boundaries.
Important you instill values and morals in your daughter while she is young so that way u know u did your job as a parent. Once she turns 18, it is her decision to choose whatever path she wants to take whether it is a good one or a bad one. I have 2 family members who grew up in homes where they were provided with stability, shelter, love, support and values but yet, they went to the path of destruction.
My husband said that it is scary to have kids and I agree with him.