title: Brain anatomy and sensorimotor gating in Asperger's syndrome.
abstract: Asperger's syndrome (an autistic disorder) is characterized by stereotyped and obsessional behaviours, and pervasive abnormalities in socio-emotional and communicative behaviour. These symptoms lead to social exclusion and a significant healthcare burden; however, their neurobiological basis is poorly understood. There are few studies on brain anatomy of Asperger's syndrome, and no focal anatomical abnormality has been reliably reported from brain imaging studies of autism, although there is increasing evidence for differences in limbic circuits. These brain regions are important in sensorimotor gating, and impaired 'gating' may partly explain the failure of people with autistic disorders to inhibit repetitive thoughts and actions. Thus, we compared brain anatomy and sensorimotor gating in healthy people with Asperger's syndrome and controls. We included 21 adults with Asperger's syndrome and 24 controls. All had normal IQ and were aged 18-49 years. We studied brain anatomy using quantitative MRI, and sensorimotor gating using prepulse inhibition of startle in a subset of 12 individuals with Asperger's syndrome and 14 controls. We found significant age-related differences in volume of cerebral hemispheres and caudate nuclei (controls, but not people with Asperger's syndrome, had age-related reductions in volume). Also, people with Asperger's syndrome had significantly less grey matter in fronto-striatal and cerebellar regions than controls, and widespread differences in white matter. Moreover, sensorimotor gating was significantly impaired in Asperger's syndrome. People with Asperger's syndrome most likely have generalized alterations in brain development, but this is associated with significant differences from controls in the anatomy and function of specific brain regions implicated in behaviours characterizing the disorder. We hypothesize that Asperger's syndrome is associated with abnormalities in fronto-striatal pathways resulting in defective sensorimotor gating, and consequently characteristic difficulties inhibiting repetitive thoughts, speech and actions.
authors.affiliation: Department of Psychological Medicine, Institute of Psychiatry, London, UK.
authors.forename: Grainne M
authors.initials: GM
authors.lastname: McAlonan
authors.forename: Eileen
authors.initials: E
authors.lastname: Daly
authors.forename: Veena
authors.initials: V
authors.lastname: Kumari
authors.forename: Hugo D
authors.initials: HD
authors.lastname: Critchley
authors.forename: Therese
authors.initials: T
authors.lastname: van Amelsvoort
authors.forename: John
authors.initials: J
authors.lastname: Suckling
authors.forename: Andrew
authors.initials: A
authors.lastname: Simmons
authors.forename: Thordur
authors.initials: T
authors.lastname: Sigmundsson
authors.forename: Kathyrn
authors.initials: K
authors.lastname: Greenwood
authors.forename: Ailsa
authors.initials: A
authors.lastname: Russell
authors.forename: Nicole
authors.initials: N
authors.lastname: Schmitz
authors.forename: Francesca
authors.initials: F
authors.lastname: Happe
authors.forename: Patricia
authors.initials: P
authors.lastname: Howlin
authors.forename: Declan G M
authors.initials: DG
authors.lastname: Murphy
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000473:pathology; D020817:Asperger Syndrome / Q000473:pathology* / Q000503:physiopathology*; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000473:pathology; D003342:Corpus Striatum / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology; D012016:Reference Values; D013216:Reflex, Startle / Q000502:physiology