The National Institute of Mental Health Study was one of many studies from the early-mid 1900s that influenced the Baltimore Longitudinal Study of Ageing (BLSA). The participants were 47 healthy, male volunteers aged from 65 to 91 years. They were recruited through responding to publicity by the Home for the Jewish Aged in Philadelphia, and the Association for Retired Civil Employees in Washington, D.C. They completed a range of tests over two weeks, and then all surviving participants were reassessed in 1961. A third follow up was completed with 19 of the original participants between 1967 and 1968.