Wall Street Journal:  Paying Them Back:

What should you do when mom and dad run out of money?

Thanks to medical and technological advances, people are living
longer—but more of them are outliving their savings. That is prompting
their children to transfer assets to their parents, say private bankers,
trust attorneys and accountants.

The strategy is counterintuitive, and can invite huge tax bills and
other financial hazards. Yet there are many different options available
to adult children, ranging from paying bills and giving money directly
to making intrafamily loans. There are even innovative "upward" trusts
specially designed to transfer assets to the older generation. …

One estate-planning strategy that is been gaining popularity over the
past few years is a trust created with the parents named as the
beneficiaries, sometimes referred to as an "upward trust." The parents
usually live off the income generated by the assets within the trust,
without tapping the core assets. … Such trusts are ideal for when the child wants to make a substantial
gift and doesn't feel confident about the parents' ability to manage the
money. … Trust attorneys and accountants can structure the trust to be as flexible or inflexible as the situation requires.