Comparative studies of human populations allow doctors and scientists to discover the root causes of human diseases and disorders so that preventive action can be taken. Epidemiological studies led to the discoveries of the relationship between smoking and cancer and to the identification of heart disease risk factors.(1) Population studies also demonstrated the mechanism of the transmission of AIDS and other infectious diseases and also showed how these diseases can be prevented.(2)

In the course of treating patients, much has been learned about the causes of diseases and disorders. Studies of human patients using sophisticated scanning technology (e.g., MRI, PET, and CT) have isolated abnormalities in the brains of patients with schizophrenia and other disorders.(3)

Cell and tissue culture (in vitro) studies are used to screen for anti-cancer, anti-AIDS, and other types of drugs, and they are also a means of producing and testing a number of other pharmaceutical products, including vaccines, antibiotics, and therapeutic proteins. The U.S. National Disease Research Interchange provides more than 120 types of human tissue to scientists investigating diabetes, cancer, cystic fibrosis, muscular dystrophy, glaucoma, and other human diseases.(4) In vitro genetic research has isolated specific markers, genes, and proteins associated with Alzheimer’s disease, muscular dystrophy, schizophrenia, and other inherited diseases.

Those who experiment on animals artificially induce disease; clinical investigators study people who are already ill or who have died. Animal experimenters want a disposable “research subject” who can be manipulated as desired and killed when convenient; clinicians must do no harm to their patients or study participants. Animal experimenters face the unavoidable fact that their artificially created “animal model” can never fully reflect the human condition, whereas clinical investigators know that the results of their work are directly relevant to people.

References:

1. Christopher Anderegg et al., “A Critical Look at Animal Experimentation,” Medical Research Modernization Committee, 2002.
2. Samuel Baron, M.D. et al., Medical Microbiology, 4th ed., University of Texas: Churchill Livingstone Inc, 1996.
3. Kelvin O. Lim et al., “In Vivo Structural Brain Assessment,” The American College of Neuropsychopharmacology, 2000.
4. National Resource Center, “Human Tissue Lists,” National Disease Research Exchange, last accessed 5 Nov. 2004.