Because you are not at least 65 years old by the end of the year, you apply the 10% threshold to all of your itemized medical costs (which include costs related to your mother). If she claimed them on her own return, she could apply the 7.5% threshold.
A statutory method of depreciation allowing accelerated rates for most types of property used in business and income-producing activities during the years 1981 through 1986. It has been superseded by the modified accelerated cost recovery system (MACRS) for assets placed in service after 1986.