Missing Alzheimer's Disease Patient Alert Program Reauthorization of 2012 - Amends the Violent Crime Control and Law Enforcement Act of 1994 to revise requirements relating to the Missing Alzheimer's Disease Patient Alert Program to direct the Attorney General to: (1) award competitive grants to assist nonprofit organizations in paying for the costs of locally based, proactive programs to protect and locate missing patients with Alzheimer's disease and related dementias; and (2) give a preference for such grants to national nonprofit organizations that have experience working with patients with Alzheimer's disease and related dementias and their families (currently, the Attorney General is directed to award a single grant to a national voluntary organization to operate the Program). Authorizes appropriations for such grants through FY2017.