David Hessl, Ph.D.

David Randal Hessl, Ph.D.


Clinical Psychology


  • Professor
  • Director, Translational Psychophysiology and Assessment Center
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UC Davis MIND Institute

2825 50th St.
Sacramento, CA 95817
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Phone: 916-703-0249
Physician Referrals: 800-4-UCDAVIS (800-482-3284)



Clinical Interests

David Hessl's clinical interests involve cognitive, emotional, and behavioral evaluation of children, adolescents and adults with neurodevelopmental disorders, especially those with fragile X syndrome, autism spectrum disorders, ADHD and learning disabilities. He also has expertise in developmental psychopathology, particularly mood and anxiety disorders, in infants and young children. 

His research focuses on genetic, environmental and hormonal contributions to cognition and behavior in children with fragile X syndrome. He also conducts collaborative studies with other researchers, investigating brain imaging, molecular genetics and neuropsychology in an effort to understand links between genetics, brain function and behavior during early development.

Research/Academic Interests

Dr. David Hessl is currently the director of the Translational Psychophysiology and Assessment Laboratory (T-PAL).  His research focuses on genetic, brain, environmental and neuroendocrine factors affecting cognition and behavior in individuals with fragile X-associated disorders. One important focus of the work in T-PAL is to develop and evaluate novel behavioral, cognitive and psychophysiological outcome measures of individuals with neurodevelopmental disorders.  These measures are designed to be used to detect improvement in functioning within controlled treatment trials.  

Current psychophysiological studies have examined abnormalities in social gaze, sensorimotor gating, sympathetic nervous system activity, hypothalamic-pituitary-adrenal axis function, and potentiated startle responses.  Other recent studies have been aimed at improving aberrant behavior and cognitive measurements in individuals with fragile X syndrome, autism spectrum, intellectual disabilities, and other neurodevelopmental disorders.  A second major focus of Dr. Hessl’s work is the study of premutation carriers of fragile X.  

As children these individuals are at increased risk for attention deficit hyperactivity disorder and autism and as older adults they become at risk for a neurodegenerative disease involving tremor, ataxia, and dementia.  Dr. Hessl (in collaboration with Dr. Susan Rivera) directs an NIMH-funded project examining genetics and the brain’s limbic system underlying emotional and psychiatric symptoms in men and women with the premutation, and a longitudinal study of premutation carriers to identify trajectories and markers of neurodegeneration..



Center/Program Affiliation

UC Davis MIND Institute


Ph.D., Child Clinical Psychology and Developmental Psychology, University of Washington, Seattle WA 1997

M.S., Child Clinical Psychology, University of Washington, Seattle WA 1995

B.A., UCLA, Los Angeles CA 1989


University of California, Berkeley, Berkeley CA 1997-1998

Honors and Awards

Jarrett Cole Clinical Award, National Fragile X Foundation, for ?Dedicated Service to Families in the Worldwide Fragile X Community?, 2012

Dean?s Team Award for Excellence, U.C. Davis School of Medicine, 2009

Select Recent Publications

Cohen S, Masyn K, Mastergeorge A, & Hessl D. Psychophysiological responses to emotional stimuli in children and adolescents with autism and fragile X syndrome. J of Clin Child and Adolescent Psychology. 2015;44(2), 250-263.

Sansone SM, Schneider A, Bickel E, Berry-Kravis E, Prescott C, & Hessl D. Improving IQ measurement in intellectual disabilities using true deviation from population norms.  J of Neurodevelopmental Disorders. 2014;6(16),1-14.

Wang JY, Hessl D, Schneider A, Tassone F, Hagerman RJ, & Rivera SM (2013). Fragile X-associated tremor/ataxia syndrome: Influence of the FMR1 gene on motor fiber tracts in males with normal and premutation alleles. JAMA Neurology. 2013;70(8), 1022-1029.

Sansone SM, Widaman KF, Hall SS, Reiss AL, Lightbody A, Kaufmann WE, Berry-Kravis E, Lachiewicz A, Brown EC, & Hessl D. Psychometric study of the Aberrant Behavior Checklist in fragile X syndrome and implications for targeted treatment.  J of Autism and Developmental Disorders. 2011;42(7), 1377-1392.

Hessl D, Wang JM, Schneider A, Koldewyn K, Le L, Iwahashi C, Tassone F, Hagerman PJ, & Rivera SM. Deficient FMRP underlies amygdala dysfunction in carriers of the fragile X premutation. Biological Psychiatry. 2011;70(9), 859-865.