A controlled study of brain structure in monozygotic twins concordant and discordant for schizophrenia.
BACKGROUND
We examined monozygotic twins concordant and discordant for schizophrenia to clarify the role of genetic and environmental factors in determining brain abnormalities.


METHODS
Magnetic resonance imaging brain scans were obtained from 14 monozygotic twin pairs concordant and 10 monozygotic pairs discordant for schizophrenia, as well as 17 pairs of monozygotic control twins. Twenty-two discordant sibling-pairs and 56 pairs of unrelated control subjects were included to assess the extent of genetic control over these structures.


RESULTS
Within-pair similarities for whole brain volume increased as pair members were more closely related genetically (monozygotic twins > siblings > unrelated control subjects). Schizophrenic twins, whether from concordant or discordant pairs, had smaller whole brain volumes than control twins. The probands of discordant pairs showed more abnormalities in hippocampal, third and lateral ventricular volumes than concordant twins.


CONCLUSIONS
Whole brain volume is under high genetic control and smaller whole brain volume is a reflection of the genetic liability to develop schizophrenia. The variation in hippocampal and ventricular volumes within discordant monozygotic pairs indicates a role for environmental factors in determining these volume abnormalities in schizophrenia. Such factors may also underlie the more extensive morphometric deviations in patients from monozygotic discordant twins than in their counterparts from concordant twins.
van Haren
Neeltje E M
NE
Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht, The Netherlands. n.haren@azu.nl.
Picchioni
Marco M
MM
McDonald
Colm
C
Marshall
Nicolette
N
Davis
Nadia
N
Ribchester
Tracey
T
Hulshoff Pol
Hilleke E
HE
Sharma
Tonmoy
T
Sham
Pak
P
Kahn
René S
RS
Murray
Robin
R
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000473:pathology*; D004200:Diseases in Twins / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D020547:Lateral Ventricles / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000453:epidemiology / Q000235:genetics / Q000473:pathology*; D035781:Siblings; D020542:Third Ventricle / Q000473:pathology; D014430:Twins, Monozygotic