There had been very few studies done on how syphilis affected people. One study was done in Norway in 1928, but it studied only white men. In the 1930s, people believed that syphilis affected people of different races in different ways. Doctors thought that African Americans' cardiovascular system was more affected by syphilis than the central nervous system. The Tuskegee study group decided to study how syphilis affected African Americans. They reasoned that they could not cure or treat people with syphilis anyway, and that they would learn things that would help doctors understand syphilis better.