title: Neuroanatomical Correlates of Theory of Mind Deficit in Parkinson's Disease: A Multimodal Imaging Study.
abstract: BACKGROUND
  Parkinson's disease (PD) patients show theory of mind (ToM) deficit since the early stages of the disease, and this deficit has been associated with working memory, executive functions and quality of life impairment. To date, neuroanatomical correlates of ToM have not been assessed with magnetic resonance imaging in PD. The main objective of this study was to assess cerebral correlates of ToM deficit in PD. The second objective was to explore the relationships between ToM, working memory and executive functions, and to analyse the neural correlates of ToM, controlling for both working memory and executive functions.
  
  
  METHODS
  Thirty-seven PD patients (Hoehn and Yahr median = 2.0) and 15 healthy controls underwent a neuropsychological assessment and magnetic resonance images in a 3T-scanner were acquired. T1-weighted images were analysed with voxel-based morphometry, and white matter integrity and diffusivity measures were obtained from diffusion weighted images and analysed using tract-based spatial statistics.
  
  
  RESULTS
  PD patients showed impairments in ToM, working memory and executive functions; grey matter loss and white matter reduction compared to healthy controls. Grey matter volume decrease in the precentral and postcentral gyrus, middle and inferior frontal gyrus correlated with ToM deficit in PD. White matter in the superior longitudinal fasciculus (adjacent to the parietal lobe) and white matter adjacent to the frontal lobe correlated with ToM impairment in PD. After controlling for executive functions, the relationship between ToM deficit and white matter remained significant for white matter areas adjacent to the precuneus and the parietal lobe.
  
  
  CONCLUSIONS
  Findings reinforce the existence of ToM impairment from the early Hoehn and Yahr stages in PD, and the findings suggest associations with white matter and grey matter volume decrease. This study contributes to better understand ToM deficit and its neural correlates in PD, which is a basic skill for development of healthy social relationships.
authors.affiliation: Department of Methods and Experimental Psychology, Faculty of Psychology and Education, University of Deusto, Bilbao, Basque Country, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Díez-Cirarda
authors.affiliation: Department of Methods and Experimental Psychology, Faculty of Psychology and Education, University of Deusto, Bilbao, Basque Country, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Ojeda
authors.affiliation: Department of Methods and Experimental Psychology, Faculty of Psychology and Education, University of Deusto, Bilbao, Basque Country, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Peña
authors.affiliation: OSATEK, MR Unit, Hospital of Galdakao, Galdakao, Basque Country, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cabrera-Zubizarreta
authors.affiliation: Neurology Service, Hospital of Galdakao, Galdakao, Basque Country, Spain.
authors.forename: María Ángeles
authors.initials: MÁ
authors.lastname: Gómez-Beldarrain
authors.affiliation: Neurodegenerative Unit, Biocruces Research Institute; Neurology Service, Cruces University Hospital, Baracaldo, Biscay, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gómez-Esteban
authors.affiliation: Department of Methods and Experimental Psychology, Faculty of Psychology and Education, University of Deusto, Bilbao, Basque Country, Spain.
authors.forename: Naroa
authors.initials: N
authors.lastname: Ibarretxe-Bilbao
mesh_terms: D000368:Aged; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D005260:Female; D066128:Gray Matter / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000473:pathology*; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011859:Radiography; D056345:Theory of Mind; D066127:White Matter / Q000033:anatomy & histology / Q000000981:diagnostic imaging