Medicaid covers the elderly and low-income families, those that are likely to not be able to afford health care, since children and the elderly often\ require more medical attention. It would seem to me that mental disabilities don't discrimintate based on age or strength, like physical issues may, however old age and decreasing physical abilities can harm mental health. These populations, with lower income, do not have as much access to mental health help, and that can further their economic situation, so this policy ensures that they will be taken care of sufficiently. At the same time, it ignores the needs of the middle-aged patients, as they must be covered by the state or in other ways.