How can I gain power of attorney to my mom's living trust?

If you know the name of the lawyer who helped set up the trust, I would give him or her a call. Realize, however, that the attorney is ethically bound not to divulge confidences between the attoeney and the client; however, a client will often have provided in the client's estate planning documentation for successor agents and successor trustees to take effect when the client becomes incapable of handling her own affairs.  Those documents will often define the standard of competency for this purpose, and name the persons responsible for determining this. You will not be able to coerce your mother into doing anything she doesn't want to do unless you get the courts involved.  I would avoid this court involvement if at all possible - it is a last resort.   Realize that if your mother is competent, she may decide that you are "at war" with her and she might remove you as a beneficiary and as a fiduciary. Having gone to three different psychologists, can they suggest anything for her benefit?  They also have ethical responsibilities, so unless you have a health care directive and waiver of HIPAA rights from your mother these professionals may also have a difficult time speaking with you - another reason to try to contact your mother's attorney first (if asking your mother directly does not work). Does your mother have anyone she trusts?  Can that person be contacted for assistance?  If she has a religious life, perhaps a minister, priest, or rabbi?