Please see https://docs.google.com/spreadsheets/d/19NwmDi8xwWjzXqhSLPDTg4CKHt5UDQXuwCnZwY8jCS8/edit?usp=sharing or Appendix A for full code and algorithm definitions.  Medicare timeframe: 2008 to 2018 (end of data availability).  Inclusion Criteria:  1. Aged > 65 years on the index date 2. No prior use of PDE5 inhibitors (sildenafil, tadalafil) and endothelin receptor antagonists (bosentan, ambrisentan, macitentan) anytime prior to cohort entry date 3. Enrollment in Medicare Part A, B, and D with no HMO coverage for 365 days prior to and including cohort entry date  Exclusion Criteria:  1. Prior history of dementia measured anytime prior to cohort entry date 2. No prior history of pulmonary arterial hypertension recorded in the 365 days prior to cohort entry date 3. Prior history of nursing home admission in the 365 days prior to the cohort entry date