Test-retest reliability of a functional MRI working memory paradigm in normal and schizophrenic subjects.
OBJECTIVE
Repeated functional magnetic resonance imaging (fMRI) studies of schizophrenic subjects may identify brain activity changes in response to interventions. To interpret the findings, however, it is crucial to know the test-retest reliability of the measures used.


METHODS
The authors scanned seven normal subjects and seven schizophrenic subjects on two occasions during performance of a working memory task. They quantified the reliability of task performance and brain activation.


RESULTS
In both groups, task performance was reliable, and all a priori regions were activated in group-averaged test and retest data. In individual schizophrenic subjects, however, indices of cognitive activation were not reliable across sessions. Normal subjects showed reasonable reliability of activation.


CONCLUSIONS
Even given reliable task performance, stable clinical status, and a stable pattern of group-averaged activation, individual subjects showed unreliable brain activation. This suggests that repeated fMRI studies of schizophrenia should control for sources of variation, both artifactual and intrinsic.
Manoach
D S
DS
Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA. dmanoach@caregroup.harvard.edu
Halpern
E F
EF
Kramer
T S
TS
Chang
Y
Y
Goff
D C
DC
Rauch
S L
SL
Kennedy
D N
DN
Gollub
R L
RL
D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D005260:Female; D005556:Form Perception / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis*; D012565:Schizophrenic Psychology