THE IDEA for undertaking this study of identical twins emerged from
a 1983 questionnaire distributed to members of the National Alliance
for the Mentally III (NAMI). The questionnaire sought information on
childhood illnesses of individuals who later developed schizophrenia.
Among the more than 2,400 replies were 15 pairs of twins. NAMI, which
had begun in 1979 as an organization for families of individuals with serious
mental illnesses, had approximately 20,000 members at the time and was
growing rapidly (it currently has over 140,000 members). Here was an
opportunity that had not previously existed to recruit identical twins with
schizophrenia and other serious mental illnesses for research purposes.

An application to study identical twins discordant for schizophrenia
(one affected, one well) and normal controls (neither affected) was submit-
ted to the National Institute of Mental Health in 1985. It was decided to
focus only on identical twins as the most effective means for distinguish-
ing nongenetic and genetic aspects of the disease. The review committee,
composed of research psychiatrists and psychologists from university set-
tings, requested that the application be revised to also include identical
twins who were concordant (both affected) for schizophrenia. The initial
grant was for 4 years, from 1987 through 1990; this was later extended
through 1992, with an increase in the number of twins to be studied and
the addition of identical twins discordant for bipolar disorder.

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