title: Fronto-striatal glutamatergic compounds in compulsive and impulsive syndromes: a review of magnetic resonance spectroscopy studies.
abstract: Compulsivity and impulsivity are cross-disorder traits observed in autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). Aberrant fronto-striatal glutamatergic signalling is core to the understanding of compulsive and impulsive disorders. In this review, the glutamate (Glu) neurochemistry of fronto-striatal circuits in paediatric and adult ASD, ADHD and OCD, as described in 59 studies, is outlined from the perspective of proton magnetic resonance spectroscopy ((1)H MRS). Despite the methodological inconsistencies between studies, two observations stand out that form possible hypotheses for future studies. Firstly, a possible increase in Glx (combination of Glu, glutamine and GABA) in the striatum across ADHD, OCD and ASD. Secondly, an increased Glx signal in the anterior cingulate cortex in paediatric ASD and ADHD but a lower Glx signal in adult ASD and ADHD. This suggests neurodevelopmental changes in fronto-striatal glutamatergic circuits across the lifespan. Future studies should incorporate more homogeneous samples, perform MRS at field strengths of at least 3 Tesla and provide much more precise and standardized information on methods to improve our understanding of fronto-striatal glutamatergic transmission in compulsive and impulsive syndromes.
authors.affiliation: Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein Noord 10 (huispost 126), 6525 EZ Nijmegen, The Netherlands. Electronic address: j.naaijen@donders.ru.nl.
authors.forename: Jilly
authors.initials: J
authors.lastname: Naaijen
authors.affiliation: P089, King's College London, Department of Neuroimaging, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF, United Kingdom. Electronic address: david.lythgoe@kcl.ac.uk.
authors.forename: David J
authors.initials: DJ
authors.lastname: Lythgoe
authors.affiliation: Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein Noord 10 (huispost 126), 6525 EZ Nijmegen, The Netherlands; Department of Radiology, Radboud University Medical Centre, Geer Groteplein 10, 6500 HB Nijmegen, The Netherlands; Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran. Electronic address: amiri.houshang@gmail.com.
authors.forename: Houshang
authors.initials: H
authors.lastname: Amiri
authors.affiliation: Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein Noord 10 (huispost 126), 6525 EZ Nijmegen, The Netherlands; Karakter Child and Adolescent Psychiatry University Centre, Reinier Postlaan 12, 6525 GC Nijmegen, The Netherlands. Electronic address: jan.buitelaar@radboudumc.nl.
authors.forename: Jan K
authors.initials: JK
authors.lastname: Buitelaar
authors.affiliation: Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein Noord 10 (huispost 126), 6525 EZ Nijmegen, The Netherlands. Electronic address: jeffrey.glennon@radboudumc.nl.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Glennon
mesh_terms: D003342:Corpus Striatum / Q000378:metabolism*; D005625:Frontal Lobe / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D009434:Neural Pathways / Q000378:metabolism; D009771:Obsessive-Compulsive Disorder / Q000473:pathology*
chemical_list: D018698:Glutamic Acid
keywords: ADHD; Autism; Compulsivity; GABA; Glutamate; Impulsivity; Magnetic resonance spectroscopy; OCD