TY - JOUR
T1 - The effect of intellectual ability on functional activation in a neurodevelopmental disorder
T2 - Preliminary evidence from multiple fMRI studies in Williams syndrome
AU - Pryweller, Jennifer R.
AU - Avery, Suzanne N.
AU - Blackford, Jennifer U.
AU - Dykens, Elisabeth M.
AU - Thornton-Wells, Tricia A.
N1 - Funding Information:
We would like to thank all study volunteers for their time and willingness to participate in this research. We are grateful for the sponsors of the Williams Syndrome Music Camp, including the Vanderbilt Kennedy Center for Research on Human Development, the Academy of Country Music’s Lifting Lives program, and the Vanderbilt Blair School of Music. We thank and acknowledge the research staff of the Williams Syndrome Music Camp who administered the KBIT-2 IQ assessments, including Elizabeth Roof, Research Coordinator. This research was supported in part by funding from the NIH Roadmap for Medical Research Postdoctoral Fellowship - Biobehavioral Intervention Training Program T32 MH075883 to TATW, National Institute of Mental Health K01-MH083052 to JUB, NIH/NICHD P30-HD15052, National Center for Research Resources - Vanderbilt CTSA Grant (1-UL-RR024975), NIH/ NIA 1P30AG038445-01, a Vanderbilt University Discovery Grant, a Vanderbilt Kennedy Center Hobbs Discovery Grant, and the Vanderbilt University Institute of Imaging Science. Portions of this work were presented at the Society for Neuroscience Annual Meeting, Washington, DC, 2011, the Gatlinburg Conference on Intellectual and Developmental Disabilities, San Antonio, TX, 2010, and the Memphis BioImaging Symposium, Memphis, TN 2010.
PY - 2012
Y1 - 2012
N2 - Background: Williams syndrome (WS) is a rare genetic disorder caused by the deletion of approximately 25 genes at 7q11.23 that involves mild to moderate intellectual disability (ID). When using functional magnetic resonance imaging (fMRI) to compare individuals with ID to typically developing individuals, there is a possibility that differences in IQ contribute to between-group differences in BOLD signal. If IQ is correlated with BOLD signal, then group-level analyses should adjust for IQ, or else IQ should be matched between groups. If, however, IQ is not correlated with BOLD signal, no such adjustment or criteria for matching (and exclusion) based on IQ is necessary. Methods: In this study, we aimed to test this hypothesis systematically using four extant fMRI datasets in WS. Participants included 29 adult subjects with WS (17 men) demonstrating a wide range of standardized IQ scores (composite IQ mean = 67, SD = 17.2). We extracted average BOLD activation for both cognitive and task-specific anatomically defined regions of interest (ROIs) in each individual and correlated BOLD with composite IQ scores, verbal IQ scores and non-verbal IQ scores in Spearman rank correlation tests. Results: Of the 312 correlations performed, only six correlations (2%) in four ROIs reached statistical significance at a P value < 0.01, but none survived correction for multiple testing. All six correlations were positive. Therefore, none supports the hypothesis that IQ is negatively correlated with BOLD response. Conclusions: These data suggest that the inclusion of subjects with below normal IQ does not introduce a confounding factor, at least for some types of fMRI studies with low cognitive load. By including subjects who are representative of IQ range for the targeted disorder, findings are more likely to generalize to that population.
AB - Background: Williams syndrome (WS) is a rare genetic disorder caused by the deletion of approximately 25 genes at 7q11.23 that involves mild to moderate intellectual disability (ID). When using functional magnetic resonance imaging (fMRI) to compare individuals with ID to typically developing individuals, there is a possibility that differences in IQ contribute to between-group differences in BOLD signal. If IQ is correlated with BOLD signal, then group-level analyses should adjust for IQ, or else IQ should be matched between groups. If, however, IQ is not correlated with BOLD signal, no such adjustment or criteria for matching (and exclusion) based on IQ is necessary. Methods: In this study, we aimed to test this hypothesis systematically using four extant fMRI datasets in WS. Participants included 29 adult subjects with WS (17 men) demonstrating a wide range of standardized IQ scores (composite IQ mean = 67, SD = 17.2). We extracted average BOLD activation for both cognitive and task-specific anatomically defined regions of interest (ROIs) in each individual and correlated BOLD with composite IQ scores, verbal IQ scores and non-verbal IQ scores in Spearman rank correlation tests. Results: Of the 312 correlations performed, only six correlations (2%) in four ROIs reached statistical significance at a P value < 0.01, but none survived correction for multiple testing. All six correlations were positive. Therefore, none supports the hypothesis that IQ is negatively correlated with BOLD response. Conclusions: These data suggest that the inclusion of subjects with below normal IQ does not introduce a confounding factor, at least for some types of fMRI studies with low cognitive load. By including subjects who are representative of IQ range for the targeted disorder, findings are more likely to generalize to that population.
KW - BOLD fMRI
KW - IQ
KW - Intellectual disability
KW - Williams syndrome
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U2 - 10.1186/1866-1955-4-24
DO - 10.1186/1866-1955-4-24
M3 - Article
C2 - 23102261
AN - SCOPUS:84881219644
SN - 1866-1947
VL - 4
SP - 1
EP - 8
JO - Journal of Neurodevelopmental Disorders
JF - Journal of Neurodevelopmental Disorders
IS - 1
ER -