title: Age-related change of neurochemical abnormality in attention-deficit hyperactivity disorder: a meta-analysis.
abstract: Prevalence and symptoms of attention-deficit hyperactivity disorder (ADHD) change with advancing age. However, neurochemical background of such age-related change is yet to be elucidated. We therefore conducted a meta-analysis of 16 proton magnetic resonance spectroscopy studies comprising 270 individuals with ADHD and 235 controls. Standardized mean differences were calculated and used as an effect size. Sensitivity analyses and meta-regression to explore the effect of age on neurochemical abnormality were performed. A random effects model identified a significantly higher-than-normal N-acetylaspartate (NAA) in the medial prefrontal cortex (mPFC), but no significant differences of other metabolites in that area. No significant difference in metabolite levels was demonstrated in any other region. Sensitivity analysis of children with ADHD revealed significantly higher-than-normal NAA, whereas no significant difference was found in adults with ADHD. Meta-regression revealed significant correlation between advanced age and normal levels of NAA in the mPFC, suggesting that age-dependent abnormality of NAA level in the mPFC is a potential neural basis of age-related change of symptoms of ADHD.
authors.affiliation: Department of Psychiatry, Tokyo Metropolitan Health and Medical Treatment Corporation, Ebara Hospital, Ota, Tokyo 145-0065, Japan; Department of Emergency and Critical Care Medicine, The University of Tokyo Hospital, Bunkyou, Tokyo 113-8655, Japan. Electronic address: yuaoki-tky@umin.ac.jp.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Aoki
authors.forename: Ryota
authors.initials: R
authors.lastname: Inokuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suwa
authors.forename: Ai
authors.initials: A
authors.lastname: Aoki
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001289:Attention Deficit Disorder with Hyperactivity / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D017397:Prefrontal Cortex / Q000378:metabolism*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate
keywords: ADD; ADHD; Attention deficit disorder; MRS; Magnetic resonance spectroscopy; Methylphenidate