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Photograph by Roswell Angier
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Mental illness may manifest itself not only psychologically, but also physiologically-in
the tissues of the brain. If so, its traces may first be identified at the
Harvard Psychiatry Brain Collection. Created last year as a subsidiary of
the Harvard Brain Tissue Resource Center, based at McLean Hospital in Belmont,
Massachusetts, the psychiatry collection facilitates the neurological study
of severe psychiatric disorders.
The Resource Center is one of only three federally funded brain banks in
the country. Founded in 1978 by Edward Bird, professor of neuropathology,
the center serves as a general brain bank for research on neurological diseases.
About 300 brains, from donors of all ages, arrive each year to be preserved
in formaldehyde or frozen in liquid nitrogen; the latter group fills nine
freezers at McLean's Mailman Research Center. The collection, which has
received more than 5,000 brains thus far, helps scientists from across the
country who seek slides of specific brain areas, or even entire brains,
for their research.
Most donations come from individuals who had Huntington's, Alzheimer's,
or Parkinson's diseases. These neurologic illnesses have corresponding family
organizations that encourage donations for postmortem brain research. "With
these disorders you can see the deterioration," says instructor in
psychiatry Jill Bolte Taylor, who directs the brain collection along with
center director Francine Benes, M.D., associate professor of psychiatry.
McLean created the brain collection to focus on the elusive problems of
psychosis, particularly schizophrenia. In contrast to the macroscopic tissue
changes in a brain afflicted with a neurological disorder, psychiatric syndromes
subtly alter anatomical structures. As Taylor puts it, "Schizophrenia
seems to be delicately infiltered throughout the tissue."
Postmortem research into serious psychiatric disorders begins with a look
at the live brain. Techniques such as magnetic resonance imaging, positron
emission tomography, and computed axial tomography can reveal brain functioning
in people with psychiatric disorders. These technologies show how different
tasks or questions affect various areas of the brain, and even how the brain
processes ideas and problems. "Individuals with psychiatric diagnoses
'light up' different areas than normal individuals," Taylor says. The
imaging techniques help to map the parts of the brain that are affected
by such diseases, and to identify areas to study in the postmortem specimens
from the brain collection.
Benes and Taylor have begun to find differences in specimens that seem
minor, but provide some of the first breakthroughs in understanding how
mental illness takes a physical form. Taylor is now making micromeasurements
of different layers in the limbic system of the cerebral cortex. Her early
results, and those of Benes, support other research indicating that the
brains of people with schizophrenia have fewer cells-less actual tissue-in
some areas of the cortex. The researchers are exploring the microcircuitry
of the brain by tagging neurotransmitters like seratonin, dopamine, and
Gaba. Superficially, Taylor says, a brain with schizophrenia "looks
the same as a healthy brain. But we find differences by counting the number
of cell types, quantities of different chemicals, and specific numbers of
contacts. We're accumulating an incredible database."
Taylor also spends a good deal of time soliciting brain donations from
people with psychiatric illnesses, relatives of the mentally ill, and healthy
individuals who can provide brains for comparison. At certain public events
she even sings a tune known as the "brain bank jingle" to encourage
donors. She sees great hope in these discoveries of slight tissue variations,
and in the research possibilities the brain collection provides. "When
we understand which cells in which areas of the brain communicate with which
chemicals and in what quantities," she says, "we can advise the
people who create medications about what system in the brain to affect,
so it can function more normally."
~ Clea Simon
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