title: Decreased frontal N-acetylaspartate levels in adolescents concurrently using both methamphetamine and marijuana.
abstract: BACKGROUND
  The potential neurochemical toxicity associated with methamphetamine (MA) or marijuana (MJ) use on the developing adolescent brain is unclear, particularly with regard to individuals with concomitant use of MA and MJ (MA+MJ). In this study, proton magnetic resonance spectroscopy (MRS) was utilized to measure in vivo brain N-acetylaspartate plus N-acetylaspartyl glutamate (tNAA, an indicator of intact neuronal integrity) levels.
  
  
  METHODS
  Three adolescent groups from Cape Town, South Africa completed MRS scans as well as clinical measures including a drug use history. Subjects included (1) nine MA (age=15.7±1.37), (2) eight MA+MJ (age=16.2±1.16) using adolescents and (3) ten healthy controls (age=16.8±0.62). Single voxel spectra were acquired from midfrontal gray matter using a point-resolved spectroscopy sequence (PRESS). The MRS data were post-processed in the fully automated approach for quantitation of metabolite ratios to phosphocreatine plus creatine (PCr+Cr).
  
  
  RESULTS
  A significant reduction in frontal tNAA/PCr+Cr ratios was seen in the MA+MJ group compared to the healthy controls (p=0.01, by 7.2%) and to the MA group (p=0.04, by 6.9%). Significant relationships were also observed between decreased tNAA/PCr+Cr ratios and drug use history of MA or MJ (total cumulative lifetime dose, age of onset, and duration of MA and MJ exposure) only in the MA+MJ group (all p<0.05).
  
  
  CONCLUSIONS
  These findings suggest that in adolescents, concomitant heavy MA+MJ use may contribute to altered brain metabolites in frontal gray matter. The significant associations between the abnormal tNAA/PCr+Cr ratios and the drug use history suggest that MA+MJ abuse may induce neurotoxicity in a dose-responsive manner in adolescent brain.
authors: Department of Psychiatry, University of Utah, Salt Lake City, UT 84108, USA.
authors: Young-Hoon
authors: YH
authors: Sung
authors: Paul D
authors: PD
authors: Carey
authors: Dan J
authors: DJ
authors: Stein
authors: Helen L
authors: HL
authors: Ferrett
authors: Bruce S
authors: BS
authors: Spottiswoode
authors: Perry F
authors: PF
authors: Renshaw
authors: Deborah A
authors: DA
authors: Yurgelun-Todd
mesh_terms: D000293:Adolescent; D019969:Amphetamine-Related Disorders / Q000473:pathology*; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001931:Brain Mapping; D004151:Dipeptides / Q000378:metabolism; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008385:Marijuana Smoking / Q000473:pathology*; D011522:Protons; D012044:Regression Analysis
chemical_list: D004151:Dipeptides; D011522:Protons; C027172:isospaglumic acid; D001224:Aspartic Acid; C000179:N-acetylaspartate