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About Sickkids
About SickKids

Paul Arnold, MD,PhD,FRCPC

The Hospital for Sick Children
Staff Psychiatrist

Research Institute
Adjunct Scientist
Genetics & Genome Biology

University of Toronto
Assistant Professor

Phone: 416-813-7530
Fax: 416-813-5326
Email: paul.arnold@sickkids.ca

Brief Biography

Dr. Arnold is an Assistant Professor at the University of Toronto, and a Scientist in the Genetics and Genome Biology program and Centre for Brain and Behaviour at SickKids.  His medical and graduate training took place at the University of Toronto, most recently with the completion of his Ph.D. in 2007.

Research Interests

Dr. Arnold’s research focuses on the genetics of childhood anxiety disorders, particularly childhood obsessive-compulsive disorder, and has been funded by major external grants from the Canadian Institutes of Health Research (CIHR) and the National Institutes of Health (NIH).  He is a member of the international Steering Committee of the first Genome-wide Association Study (GWAS) of OCD.

Clinical Interests

Dr. Arnold is a Staff Psychiatrist within the Department of Psychiatry at SickKids, and he is also the head of the Anxiety Disorders Program where he specializes in the assessment and pharmacological treatment of children with Obsessive-Compulsive Disorders (OCD).

External Funding

Psychiatry Endowment Fund, Department of Psychiatry, Hospital for Sick Children. “The White Matter Integrity and Neural Activation within Frontal-Striatal Circuitry in Childhood OCD”. Principal Investigator: S Ameis, PD Arnold; Co-investigators: C Dockstader, D Mabbott, RJ Schachar, S Mendlowitz, E Widjaja.

Canadian Institute of Health Research (CIHR) Operating Grant. “Genome-wide association study of childhood obsessive-compulsive traits in a general population sample”. Principal Investigator: PD Arnold; Co-investigators: RJ Schachar, J Crosbie, AD Paterson.

Ontario Research Fund - Global Leadership Round in Genomics & Life Sciences Competition (GL2 Competition).  “Autism Spectrum and Associated Neurodevelopmental Disorders: Genomes to Outcomes”. Principal Investigators: S Scherer, P Szatmari. Role: Co-investigator.

National Institutes of Health, Collaborative RO1 Grant.  “Brain Chemistry and Genetics of Pediatric OCD”. Principal Investigators: DR Rosenberg (Wayne State), GL Hanna (University of Michigan), PD Arnold (Hospital for Sick Children).

Canadian Institute of Health Research (CIHR). “Exploring Copy Number Variation in Attention Deficit Hyperactivity Disorder”. Principal Investigator: R Schachar; Co-Investigators: J Crosbie, C Marshall, S Scherer, PD Arnold.

Canadian Institute of Health Research (CIHR). “Exploring the Genetic Architecture of ADHD Phenotypes and Endophenotypes in a General Population Sample”. Principal Investigators: R Schachar, J Crosbie; Co-investigator: PD Arnold.

Ontario Mental Health Foundation, Type B Grant.  “Obsessive Compulsive Disorder (OCD): An innovative genetic study utilizing intermediate phenotypes and pharmacogenetics”. Principal Investigator: MA Richter; Co-Investigators: JL Kennedy, PD Arnold, E Mundo, F Macciardi, L Summerfeldt.


2009  Associate, American College of Neuropsychopharmacology (2009 – 2016)

2008  The John M. Cleghorn Award for excellence as a Newly Established Researcher – Department of Psychiatry, University of Toronto


Arnold PD, Hanna GL, Rosenberg DR. Imaging the amygdala: Changing the face of gene discovery in child psychiatry. Journal of the American Academy of Child and Adolescent Psychiatry 49(1): 7-10. (2010).

 Ornstein TJ, Arnold PD, Manassis K, Mendlowitz S, Schachar RJ. Neuropsychological performance in childhood OCD: A preliminary study. Depression and Anxiety 27(4):372-80 (2010). Epub Dec 3, 2009.

Nicolini H, Arnold PD, Nestadt G, Lanzagorta N, Kennedy JL: Overview of genetics and obsessive-compulsive disorder. Psychiatry Research 170:7-14 (2009).

Arnold PD, MacMaster FP, Richter MA, Hanna GL, Sicard T, Burroughs E, Mirza Y, Easter PC, Rose M, Kennedy JL, Rosenberg DR: Glutamate receptor gene (GRIN2B) associated with reduced anterior cingulate glutamatergic concentration in pediatric obsessive-compulsive disorder. Psychiatry Research: Neuroimaging 172(2): 136-139 (2009) “Recommended” rating by Faculty of Medicine 1000”.

 Arnold PD, MacMaster FP, Hanna GL, Richter MA, Sicard T, Burroughs E, Mirza Y,Easter PC, Rose M, Kennedy JL, Rosenberg DR: Glutamate system genes associated with ventral prefrontal and thalamic volume in pediatric obsessive-compulsive disorder.  Brain Imaging and Behavior 3: 64-76. (2009).

 Arnold PD, Sicard T, Burroughs E, Richter MA, Kennedy JL: Glutamate transporter gene (SLC1A1) associated with obsessive-compulsive disorder. Archives of General Psychiatry. 63(7): 769-76. (2006).

Hu X-Z, Lipsky RH, Zhu G, Akhtar LA, Taubman J, Greenberg BD, Xu K, Arnold PD, Richter MA, Kennedy JL, Murphy D, Goldman D: Serotonin transporter gain-of-function polymorphisms are linked to obsessive-compulsive disorder. American Journal of Human Genetics. Am J Hum Genet. 78:815-826 (2006). Epub March 28, 2006.

 Arnold PD, Ickowicz I, Chen S, Schachar RJ: Attention deficit disorder with and without obsessive compulsive disorder: clinical characteristics, cognitive assessment and risk factors. Canadian Journal of Psychiatry. 50(1): 59-66 (2005).

 Arnold PD, Rosenberg DR, Mundo E, Tharmalingam S, Kennedy JL, Richter MA. Association of a glutamate (NMDA) subunit receptor gene (GRIN2B) with obsessive-compulsive disorder: a preliminary study. Psychopharmacology (Berl). 174(4): 530-538 (2004).  Epub 2004 Apr 09.

Arnold PD, Siegel-Bartelt J, Cytrynbaum C, Teshima I, Schachar R: Velo-cardio-facial syndrome: Implications of microdeletion 22q11 for schizophrenia & mood disorders. American Journal of Medical Genetics (Neuropsychiatric Genetics) 105:354-362. (2001).