title: Axonal injury within language network in primary progressive aphasia.
abstract: Primary progressive aphasia (PPA) is characterized by an isolated progressive impairment of word use and comprehension reflecting the distribution of pathological processes within the left hemisphere. We used proton magnetic resonance spectroscopy (1H-MRS) to study in vivo the integrity of axonal fibers connecting perisylvian language areas in 11 patients with PPA, 11 subjects with Alzheimer's disease, and 22 controls. Brain metabolites (N-acetylaspartate, myoinositol, choline, creatine) were measured bilaterally within a volume of interest located in the central portion of the superior longitudinal fasciculus, a long associative bundle connecting Broca's area with Wernicke's area, and other language regions of the temporal lobe. In the PPA group, there was an asymmetrical N-acetylaspartate to creatine ratio reduction compared with Alzheimer's disease and controls, with greater changes on the left side. The myoinositol to creatine ratio was increased in the PPA group bilaterally compared with controls. The choline to creatine ratio did not differ among the three groups. These results indicate an asymmetrical focal axonal injury within the language network in PPA. The marked difference in the distribution of N-acetylaspartate to creatine between PPA and Alzheimer's disease suggests that proton magnetic resonance spectroscopy may help to differentiate between these two conditions.
authors.affiliation: Institute of Psychiatry, London, United Kingdom. spjumrc@iop.kcl.ac.uk
authors.forename: Marco
authors.initials: M
authors.lastname: Catani
authors.forename: Massimo
authors.initials: M
authors.lastname: Piccirilli
authors.forename: Antonio
authors.initials: A
authors.lastname: Cherubini
authors.forename: Roberto
authors.initials: R
authors.lastname: Tarducci
authors.forename: Tiziana
authors.initials: T
authors.lastname: Sciarma
authors.forename: Gianni
authors.initials: G
authors.lastname: Gobbi
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Pelliccioli
authors.forename: Stefania Maria
authors.initials: SM
authors.lastname: Petrillo
authors.forename: Umberto
authors.initials: U
authors.lastname: Senin
authors.forename: Patrizia
authors.initials: P
authors.lastname: Mecocci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism / Q000473:pathology; D018888:Aphasia, Primary Progressive / Q000378:metabolism / Q000473:pathology*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001369:Axons / Q000473:pathology*; D003401:Creatine / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011522:Protons; D013702:Temporal Lobe / Q000378:metabolism / Q000473:pathology*
chemical_list: D011522:Protons; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine