The impact of Medicare Part D on cognitive functioning at older ages.

Research has shown that the establishment of Medicare prescription drug benefit in 2006 leads to improvement in medication adherence and mortality outcomes. Despite a clear connection between physical/mental health and the risk of dementia, little is known about the extent to which this reform has affected the cognitive functioning of the elderly. Using data from the Health and Retirement Study and difference-in-differences approach, this study provides the first evidence on the cognition-enhancing effects of Medicare Part D. Our estimates show that Part D implementation is associated with 1.6% increase in cognitive functioning or 1.1-year delay of cognitive aging among benefit-eligible persons. Further analyses indicate that most of the cognitive benefits accrue to the vulnerable populations who previously lacked prescription drug coverage, and that a reduction in cardiovascular mortality is the most likely pathway through which the expansion improved cognitive functioning.