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Volumes of Brain Structures in Twins Discordant for Schizophrenia
William F. C. Baaré, MS;
Clarine J. van Oel, MS;
Hilleke E. Hulshoff Pol, PhD;
Hugo G. Schnack, PhD;
Sarah Durston, MS;
Margriet M. Sitskoorn, PhD;
René S. Kahn, MD, PhD
Arch Gen Psychiatry. 2001;58:33-40.
Background The study was designed to examine the relative contributions of genetic
and nongenetic factors to structural brain abnormalities in schizophrenia
and subjects at risk to develop the disorder.
Methods The brains of 15 monozygotic and 14 same-sex dizygotic twins discordant
for schizophrenia (patients) and 29 healthy twins pair-wise matched for zygosity,
sex, age, and birth order were studied using high-resolution magnetic resonance
imaging scans.
Results Intracranial and whole-brain corrected frontal lobe volumes were smaller
(4.6% and 2.7%, respectively) in discordant monozygotic twins as compared
with healthy monozygotic twins. Irrespective of zygosity, discordant twins
had smaller whole-brain (2%), parahippocampal (9%), and hippocampal (8%) volumes
than healthy twins. Moreover, patients had smaller whole-brain volumes (2.2%)
than their nonschizophrenic cotwins, who in turn had smaller brains (1%) than
healthy twins. Lateral and third-ventricle volumes were increased in discordant
dizygotic twins as compared with healthy dizygotic twins (60.6% and 56.6%,
respectively). Finally, within discordant twins, lateral ventricles were larger
(14.4%) in patients than in their nonschizophrenic cotwins.
Conclusions Smaller intracranial volumes in the monozygotic patients and their cotwins
suggest that increased genetic risk to develop schizophrenia is related to
reduced brain growth early in life. The additional reduction in whole-brain
volume found in the patients suggests that the manifestation of the disorder
is related to (neurodegenerative) processes that are most likely nongenetic
in origin.
From the Department of Psychiatry, University Medical Center, Utrecht,
the Netherlands.
Corresponding author and reprints: René S. Kahn, MD, PhD,
Department of Psychiatry, University Medical Center Utrecht, Heidelberglaan
100, 3584 CX Utrecht, the Netherlands (e-mail: r.kahn{at}psych.azu.nl).
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