title: ERP abnormalities elicited by word repetition in fragile X-associated tremor/ataxia syndrome (FXTAS) and amnestic MCI.
abstract: BACKGROUND
  Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder caused by FMR1 gene premutations, typically associated with frontal-subcortical type cognitive impairments. High prevalence (~50%) of superimposed Alzheimer׳s pathology has been reported in FMR1 premutation carriers, and standardized neuropsychological tests have not yielded any robust discriminators between FXTAS and Alzheimer׳s disease (AD) dementia. The similarities/differences in memory processes between FXTAS and early AD remain underexplored.
  
  
  METHODS
  32-channel event-related potentials (ERPs) were obtained from a semantic judgment task in which semantically congruous (50%) and incongruous pairs repeat pseudorandomly. The N400 and late positive component (LPC) of 25 FXTAS patients (M(age)=71.2, MMSE=26.6) were compared to a matched group of 25 patients with MCI or early AD (1 mild AD dementia, 24 amnestic MCI, of whom 18 later converted to AD; M(age)=73.4, MMSE=26.4), and 25 healthy elderly.
  
  
  RESULTS
  Both patient groups showed similar reductions in the N400 repetition effect and N400 congruity effect amplitudes, compared to controls, reflecting abnormal semantic priming and repetition priming. The MCI/AD group, however, had significantly smaller LPC word repetition effects and poorer learning and memory on the CVLT than FXTAS. The LPC and N400 repetition effects both correlated with verbal memory across all subjects, but only N400 correlated with memory in FXTAS.
  
  
  CONCLUSIONS
  FXTAS patients show relative sparing of the LPC repetition effect, and less disruption of explicit memory than prodromal/early AD. N400 abnormalities in FXTAS appear to account for much of their mild impairments in verbal learning and memory.
authors.affiliation: University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA. Electronic address: jchyang@ucdavis.edu.
authors.forename: Jin-Chen
authors.initials: JC
authors.lastname: Yang
authors.affiliation: University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
authors.forename: Lillian
authors.initials: L
authors.lastname: Chi
authors.affiliation: University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Teichholtz
authors.affiliation: University of California Davis, M.I.N.D. Institute, School of Medicine, Sacramento, CA, USA; University of California Davis, Department of Pediatrics, School of Medicine, Sacramento, CA, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Schneider
authors.affiliation: University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
authors.forename: Rawi
authors.initials: R
authors.lastname: Nanakul
authors.affiliation: University of California San Diego, Department of Neurosciences, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA.
authors.forename: Ralph
authors.initials: R
authors.lastname: Nowacki
authors.affiliation: University of California Davis, Department of Psychiatry and Behavioral Sciences, School of Medicine, Sacramento, CA, USA.
authors.forename: Andreea
authors.initials: A
authors.lastname: Seritan
authors.affiliation: University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Reed
authors.affiliation: University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
authors.affiliation: University of California San Diego, Department of Neurosciences, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA.
authors.forename: Vicente J
authors.initials: VJ
authors.lastname: Iragui
authors.affiliation: University of California San Diego, Department of Cognitive Sciences, San Diego, CA, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Kutas
authors.affiliation: University of California Davis, Department of Biochemistry and Molecular Medicine, Davis, CA, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Hagerman
authors.affiliation: University of California Davis, M.I.N.D. Institute, School of Medicine, Sacramento, CA, USA; University of California Davis, Department of Pediatrics, School of Medicine, Sacramento, CA, USA.
authors.forename: Randi J
authors.initials: RJ
authors.lastname: Hagerman
authors.affiliation: University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA. Electronic address: jmolichney@ucdavis.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Olichney
mesh_terms: D000368:Aged; D000647:Amnesia / Q000150:complications / Q000503:physiopathology; D001259:Ataxia / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D060825:Cognitive Dysfunction / Q000150:complications / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D005600:Fragile X Syndrome / Q000503:physiopathology*; D006801:Humans; D008297:Male; D061212:Memory, Episodic; D060865:Repetition Priming; D012660:Semantics; D014202:Tremor / Q000503:physiopathology*
keywords: Dementia; EEG; Fragile X permutation; Language; Memory
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