title: Brain morphological changes and early marijuana use: a magnetic resonance and positron emission tomography study.
abstract: BACKGROUND
  The focus of this report is on the possible role that the age of first use of marijuana may play on brain morphology and function.
  
  
  METHODS
  Magnetic resonance imaging (MRI) and positron emission tomography (PET) were utilized to study 57 subjects. Brain volume measures (whole brain, gray matter, white matter and lateral ventricle volumes), global cerebral blood flow (CBF) and body size were evaluated.
  
  
  RESULTS
  There are three primary findings related to age of first use of marijuana. Subjects who started using marijuana before age 17, compared to those who started later, had smaller whole brain and percent cortical gray matter and larger percent white matter volumes. Functionally, males who started using marijuana before 17 had significantly higher CBF than other males. Both males and females who started younger were physically smaller in height and weight, with the effects being greater in males.
  
  
  CONCLUSIONS
  These findings suggest that the age at which exposure to marijuana begins is important. Early adolescence may be a critical period for effects that are not present when exposure begins later. These results are discussed in light of reported effects of marijuana on gonadal and pituitary hormones.
authors.affiliation: Department of Psychiatry, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: W
authors.initials: W
authors.lastname: Wilson
authors.forename: R
authors.initials: R
authors.lastname: Mathew
authors.forename: T
authors.initials: T
authors.lastname: Turkington
authors.forename: T
authors.initials: T
authors.lastname: Hawk
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: J
authors.initials: J
authors.lastname: Provenzale
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001824:Body Constitution; D001921:Brain / Q000098:blood supply / Q000187:drug effects* / Q000473:pathology; D002186:Cannabinoids / Q000009:adverse effects*; D002508:Cephalometry; D002540:Cerebral Cortex / Q000098:blood supply / Q000187:drug effects / Q000473:pathology; D002552:Cerebral Ventricles / Q000098:blood supply / Q000187:drug effects / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000175:diagnosis* / Q000503:physiopathology; D012039:Regional Blood Flow / Q000187:drug effects; D014055:Tomography, Emission-Computed
chemical_list: D002186:Cannabinoids