Significant changes began in the early 1900s in terms of medicine and psychiatry. Laboratory science allowed scientists to explore the brain for causes of mental illness. Neurologists and microbiologists concluded that mental illness was a disorder of the nervous system. With this information, psychiatric illnesses were now viewed as medical problems. Psychoanalysis, developed by Sigmund Freud as a method of analyzing people’s lives, was used as an effective way to determine how stresses stemmed from negative influences of childhood events.