Bruce Pennington, Ph.D.
(303) 871-4403
bpenning@nova.psy.du.eduMy research focuses on disorders of cognitive development: developmental dyslexia, attention deficit hyperactivity disorder (ADHD), and several mental retardation syndromes (early treated phenylketonuria, fragile X syndrome, Down syndrome, and infantile autism). Our lab includes a Child Neuropsychology Clinic, and we have had clinical experience with all these disorders. The long-term goal of our research is to understand how different genetic influences alter brain development to produce each disorder's cognitive strengths and weaknesses. My colleagues and I have pursued this goal by working forward from genotype to phenotype, and backward from phenotype to genotype.
In the first type of work, we have studied the neuropsychological effects of known genetic alterations, including point mutations such as those that produce phenylketonuria, trinucleotide repeats such as those that produce fragile X syndrome, or aneuploidies such as those that produce Turner syndrome or Down syndrome. In some of these disorders, we have been able to demonstrate a dose-response relation between an aspect of the disorder's biology and the severity of the neurocognitive phenotype. In the Down syndrome work, we have begun to collaborate with other scientists who have developed mouse models of Down syndrome.
In the second type of work, we are using both behavior and molecular genetic methods to investigate the etiology of two behaviorally-defined disorders, dyslexia and ADHD, and their etiological overlap. We collaborated with researchers at Boys Town National Research Hospital in Omaha, Nebraska, and at the Institute for Behavioral Genetics in Boulder, Colorado, on a project that in 1994 identified the approximate location on chromosome 6 of a genetic locus influencing dyslexia. In earlier work, we had identified a possible separate locus on chromosome 15 which also influences dyslexia. The chromosome 6 finding has now been replicated by three different laboratories. Along with Shelley Smith at Boys Town National Research Hospital, we are now embarking on three extensions of this linkage work: a whole genome search for other genes which may influence dyslexia; a linkage study of ADHD which will provide a direct test of the genetic overlap between dyslexia and ADHD; and, a study of developmental phonology disorder, which is cofamilial with dyslexia and also overlaps with it phenotypically.
In collaboration with Pauline Filipek at the University of California at Irvine, we are studying brain morphometry in dyslexic and control twins using structural magnetic resonance imaging (MRI). This study aims to identify brain structures correlated with dyslexia, test the degree of genetic and environmental influences on those structures, then test the etiological overlap between these brain structures and dyslexia. This twin MRI study illustrates a second method for testing relations between genes, brain, and behavior.
Another area of interest is defining the neuropsychological phenotype in individuals with infantile autism and their relatives. A wide range of neuropsychological models have been proposed to account for the symptoms that define autism. Sally Rogers and I have a program project grant which is testing which of these candidate deficits -- executive functions, imitation, emotion, social cognition, and sensory reactivity - are indeed primary in autism.
Our clinical experience with all of these disorders has helped focus our research, and our results have led to improvements in their diagnosis and treatment.
I regularly teach courses on developmental psychopathology and developmental neuropsychology
Recent Publications:1. Aman, C.J., Roberts, Jr., R.J., & Pennington, B.F. (1998). A neuropsychological examination of the underlying deficit in ADHD: The frontal lobe vs. right parietal lobe theories. Developmental Psychology, 34, 956-969.2. Cardon, L.R., DeFries, J.C., Fulker, D.W., Kimberling, W.J., Pennington, B.F., & Smith, S.D. (1994). Quantitative trait locus for reading disability on chromosome 6. Science, 265, 276-279.
3. Gayan, J., Smith, S.D., Cherny, S.S., Cardon, L.R., Fulker, D.W., Brower, A.M., Olson, R.K., Pennington, B.F., & DeFries, J.C. (1999). Quantitative-trait locus for specific language and reading deficits on chromosome 6p. American Journal of Human Genetics, 64, 157-164.
4. Griffith, E.M., Pennington, B.F., Wehner, E.A., & Rogers, S.J. (1999). Executive functions in young children with autism. Child Development, 70, 817-832.
5. Pennington, B.F., & Ozonoff, S. (1996). Executive functions and developmental psychopathology. Journal of Child Psychology and Psychiatry, 37, 51-87.
6. Pennington, B.F., Filipek, P.A., Lefly, D., Churchwell, J., Kennedy, D.N., Simon, J.H., Filley, C.M., Galaburda, A., Alarcon, M., & DeFries, J.C. (1999). Brain morphometry in reading-disabled twins. Neurology, 53, 723-729.
POSTDOCTORAL RESEARCH TRAINING PROGRAM IN DEVELOPMENTAL PSYCHOBIOLOGYDepartment of Psychiatry
University of Colorado Denver
Denver, CO 80262For additional Information E-mail:
Martin.Reite@UCHSC.edu
If you have any comments or suggestions, feel free to E-mail:
Linda.Greco-Sanders@UCHSC.edu
