Many of the social, economic, and political problems
facing people with schizophrenia are due to a misconception
in the community that schizophrenia is not a biologically
based disease but a myth. Because the diagnosis is based
on self-reported symptoms, it is difficult for many people
to acknowledge that schizophrenia is real. One goal of
psychophysiological research has been to anchor both diagnosis
and symptoms in biological reality. Reduction of the amplitude
of the P300 component of the event-related potential (ERP)
is the most replicable biological marker of the disease.
Data are presented suggesting that P300 is both a state
and a trait marker of the disease and may be sensitive
to the progressive/degenerative course of the disease.
Although the P300 tracks changes in clinical symptoms,
it remains reduced even in patients in relative remission.
P300 amplitude reduction is related to enduring negative
symptoms, waning of attention, and gray matter volume deficits.
ERP components other than P300 can also manifest the biological
reality of various symptoms of the disease.