title: Absence of age-related prefrontal NAA change in adults with autism spectrum disorders.
abstract: Atypical trajectory of brain growth in autism spectrum disorders (ASDs) has been recognized as a potential etiology of an atypical course of behavioral development. Numerous neuroimaging studies have focused on childhood to investigate atypical age-related change of brain structure and function, because it is a period of neuron and synapse maturation. Recent studies, however, have shown that the atypical age-related structural change of autistic brain expands beyond childhood and constitutes neural underpinnings for lifelong difficulty to behavioral adaptation. Thus, we examined effects of aging on neurochemical aspects of brain maturation using 3-T proton magnetic resonance spectroscopy ((1)H-MRS) with single voxel in the medial prefrontal cortex (PFC) in 24 adult men with non-medicated high-functioning ASDs and 25 age-, IQ- and parental-socioeconomic-background-matched men with typical development (TD). Multivariate analyses of covariance demonstrated significantly high N-acetylaspartate (NAA) level in the ASD subjects compared with the TD subjects (F=4.83, P=0.033). The low NAA level showed a significant positive correlation with advanced age in the TD group (r=-0.618, P=0.001), but was not evident among the ASD individuals (r=0.258, P=0.223). Fisher's r-to-z transformation showed a significant difference in the correlations between the ASD and TD groups (Z=-3.23, P=0.001), which indicated that the age-NAA relationship was significantly specific to people with TD. The current (1)H-MRS study provided new evidence that atypical age-related change of neurochemical aspects of brain maturation in ASD individuals expands beyond childhood and persists during adulthood.
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aoki
authors.forename: O
authors.initials: O
authors.lastname: Abe
authors.forename: N
authors.initials: N
authors.lastname: Yahata
authors.forename: H
authors.initials: H
authors.lastname: Kuwabara
authors.forename: T
authors.initials: T
authors.lastname: Natsubori
authors.forename: N
authors.initials: N
authors.lastname: Iwashiro
authors.forename: Y
authors.initials: Y
authors.lastname: Takano
authors.forename: H
authors.initials: H
authors.lastname: Inoue
authors.forename: Y
authors.initials: Y
authors.lastname: Kawakubo
authors.forename: W
authors.initials: W
authors.lastname: Gonoi
authors.forename: H
authors.initials: H
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Murakami
authors.forename: M
authors.initials: M
authors.lastname: Katsura
authors.forename: Y
authors.initials: Y
authors.lastname: Nippashi
authors.forename: H
authors.initials: H
authors.lastname: Takao
authors.forename: A
authors.initials: A
authors.lastname: Kunimatsu
authors.forename: H
authors.initials: H
authors.lastname: Matsuzaki
authors.forename: K J
authors.initials: KJ
authors.lastname: Tsuchiya
authors.forename: N
authors.initials: N
authors.lastname: Kato
authors.forename: K
authors.initials: K
authors.lastname: Kasai
authors.forename: H
authors.initials: H
authors.lastname: Yamasue
mesh_terms: D000328:Adult; D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D020817:Asperger Syndrome / Q000378:metabolism*; D001321:Autistic Disorder / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D015999:Multivariate Analysis; D017397:Prefrontal Cortex / Q000378:metabolism*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate