Impact of cognitive performance on the reproducibility of fMRI activation in schizophrenia

Olivier Maïza
J Psychiatry Neurosci. 2010-11-01; 35(6): 378-389
DOI: 10.1503/jpn.090103

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1. J Psychiatry Neurosci. 2010 Nov;35(6):378-89. doi: 10.1503/jpn.090103.

Impact of cognitive performance on the reproducibility of fMRI activation in
schizophrenia.

Maïza O(1), Mazoyer B, Hervé PY, Razafimandimby A, Dollfus S, Tzourio-Mazoyer N,
Andreassen OA.

Author information:
(1)Centre d’Imagerie-Neurosciences et Applications aux Pathologies, Universités
de Caen et Paris Descartes, Centre Hospitalier Universitaire de Caen, Caen,
France.

BACKGROUND: Longitudinal functional magnetic resonance imaging (fMRI) studies in
patients with schizophrenia allow exploration of the course of the illness and
brain activity after therapy. A crucial question, however, is whether fMRI
findings are reliable, because they can be affected by performance deficits in
patients with schizophrenia. Our aim was to evaluate the reproducibility of fMRI
activations in highly integrated language areas in patients with schizophrenia,
taking into account task performance.
METHODS: Ten patients with schizophrenia and 10 matched healthy controls were
scanned twice, 21 months apart, while performing a story comprehension task. The
reproducibility of the activations in each participant was evaluated globally by
the percentage of spatial overlap between the 2 sessions and locally by a
voxel-wise computation of the between-session relative standard deviation. We
performed between-group comparisons both with and without the inclusion of
comprehension scores (measuring task performance) as a covariate.
RESULTS: On average, patients with schizophrenia had significantly lower
comprehension scores than controls (4.5/12 v. 7.8/12, p = 0.002). The mean
spatial overlap between fMRI sessions was 30.6% in the patient group and 47.0% in
the control group (p = 0.017). Locally, the lower reproducibility in patients was
most prominent in the left posterior middle temporal gyrus, inferior frontal
gyrus and medial prefrontal cortex (p < 0.001 uncorrected for multiple
comparisons). Comprehension scores were positively correlated with both
reproducibility measures in patients (overlap: r = 0.82, p = 0.004; relative
standard deviation: several significant clusters at p < 0.001). When we included
the comprehension scores as a covariate, most of the local between-group
differences in reproducibility were removed, and the difference in overlap was
not significant.
LIMITATIONS: Owing to the small sample size, we could not investigate the impact
of clinical subtypes and different types of medications on reproducibility.
CONCLUSION: Our findings suggest that the greater variability in activation in
patients with schizophrenia compared with controls concerns high-level areas and
is mainly attributable to deficient task performance. Consequently, cognitive
performance must be carefully controlled when longitudinal fMRI studies are
undertaken.

DOI: 10.1503/jpn.090103
PMCID: PMC2964368
PMID: 20731962 [Indexed for MEDLINE]


Auteurs Bordeaux Neurocampus