Claiming a dependent- parent

My parents don't live with me. My mom is retired and on social security and is receiving medicaid, and my dad is almost 64 and thinking about retiring, but is still working part time. They are having a hard time paying their rent, and I was thinking of helping them out. If I start paying for their rent and other expenses, can I claim them as dependents even if they don't live with me? Can I claim them even if my dad is still working and has an income? If I am able to claim them as dependents, what are the pros and cons- how would this affect my taxes and theirs.