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University Medical Center Groningen
Department of Child and Adolescent Psychiatry
Hanzeplein 1, XA10
9713 GZ Groningen
The Netherlands
UMCG Website

  Groningen logo
Accare Child Study Center
Attn. Research
Lübeckweg 2 

The Netherlands
Accare Website
Study Protocol
Principal investigator
Prof.dr. Pieter J. Hoekstra
Phone: +31-50-3681100
Fax: +31-50-3681122
Co-Principal Investigator:
Dr. Andrea Dietrich
Phone: +31-50-3681100
Fax: +31-50-3681122
Clinical Staff:
Marieke Messchendorp, MSc
Phone: +31-50-3681100
Fax: +31-50-3681122

Institute Description

The University Medical Center Groningen (UMCG) is a leading Dutch institute for medical research. Accare is a clinical and outpatient mental health care center for children and adolescents in the Northern parts of the Netherlands. The child and adolescent psychiatry clinical service at Accare has access to over 2000 new child and adolescent patients per year and has a dedicated tic and OCD specialty clinic. The UMCG Department of Child and Adolescent Psychiatry, liaised with Accare Child Study Center, is specialized in research in neurodevelopmental disorders with a focus on tic disorders, ADHD and Autism Spectrum Disorders. This research is embedded in an interdisciplinary research institute, the Graduate School of Behavioral and Cognitive Neurosciences in Groningen, the Netherlands.

Short profile of group

Pieter J. Hoekstra, MD, PhD, is a child and adolescent psychiatrist and full professor at the UMCG Department of Child and Adolescent Psychiatry, director of research, and coordinator of the speciality tic disorders of Accare. He has extensive clinical and research experience in pediatric tic disorders, with a focus on the role of autoimmunity and on gene*environment interactions. He is active in genetic, immunologic, pharmacological, neuroimaging, epidemiological, nutritional, and parent training studies. He is also involved in a number of collaborative studies including medication trials (for children with autism spectrum disorders, ADHD and mental retardation, respectively) and large epidemiological studies. He leads a vibrant research department with several senior researchers, postdocs and a large number of PhD students, embedded in a variety of research projects.

Prof. Hoekstra coordinated the longitudinal European Multicentre Tics in Children Studies (EMTICS), a large European Union FP7 funded multicenter cohort study that addresses genetic, immunologic, and enviornmental susceptibility factors for the onset and course of pediatric and adolescent tic disorders ( He was also PI within the FP7 funded Marie Curie Initial Training Network TS-EUROTRAIN (, a study of the genetic, neural, and enviornmental basis of TS and comorbid disorders.

Andrea Dietrich, MSc, PhD, is psychologist and senior research scientist at Accare and the UMCG Department of Child and Adolescent Psychiatry. She is responsible for the day-to-day coordination within TIC Genetics in Europe since the study started in 2011, and has also been involved in several other multicenter studies, such as EMTICS, TS-Eurotrain, Aggressotype/MATRICS (, and Eat2beNICE ( Dr. Dietrich has a background in clinical, developmental and neuropsychology. Her clinical experience spans a variety of childhood and adult psychiatric disorders. During her PhD, she investigated the stress physiology of internalizing and externalizing disorders in children and adolescents. Her research interests focus on the etiology of Tourette Syndrome, ADHD and disruptive disorders. She has been (co)supervisor of numerous PhD projects, including studies of the role of genes, gene-enviornment interactions, neuropsychology and neuroimaging related to these disorders. Her clinical research interests focus on the role of contextual factors (child, parent, family and enviornmental factors) in the treatment of child and adolescent psychiatric disorders.

Marieke Messchendorp, MSc, is a psychologist and works as a research assistant at the UMCG Department of Child and Adolescent Psychiatry. She is responsible for the day-to-day tasks of TIC Genetics, like the recruitment and interviews. Marieke has worked as a research assistant for lots of different studies, like Trails (, NESDA ( and TRANS-ID (