title: Brain structure and function differences in monozygotic twins: possible effects of breast cancer chemotherapy.
abstract: OBJECTIVE
  Adjuvant chemotherapy has been associated with mild cognitive decline among a subset of breast cancer survivors. Late cognitive effects after chemotherapy can have a deleterious impact on survivor quality of life and functional health; however, the etiology of chemotherapy-related cognitive dysfunction remains unknown.
  
  
  METHODS
  We present a case of monozygotic twins who are discordant for breast cancer and chemotherapy exposure (ie, one twin contracted breast cancer and underwent chemotherapy, and the other had no breast cancer). As part of a larger study, each was evaluated with standardized, self-report measures of cognitive function, standard neuropsychological tests, and structural and functional magnetic resonance imaging (MRI).
  
  
  RESULTS
  Results indicated small differences in neuropsychological test performance but striking contrasts in self-reported cognitive complaints and structural and functional MRI images. Specifically, the twin who underwent chemotherapy had substantially more subjective cognitive complaints, more white matter hyperintensities on MRI, and an expanded spatial extent of brain activation during working memory processing than her nonaffected twin.
  
  
  CONCLUSIONS
  This case illustrates possible physiologic mechanisms that could produce long-term cognitive complaints among chemotherapy recipients and help formulate hypotheses for further empirical study in the area of chemotherapy-associated cognitive dysfunction.
authors.affiliation: Department of Rehabilitation Medicine, Eastern Maine Medical Center, Bangor, ME 04401, USA. rferguson@emh.org
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ferguson
authors.forename: Brenna C
authors.initials: BC
authors.lastname: McDonald
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Saykin
authors.forename: Tim A
authors.initials: TA
authors.lastname: Ahles
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects*; D001057:Apolipoproteins E; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology / Q000503:physiopathology*; D001943:Breast Neoplasms / Q000188:drug therapy*; D003072:Cognition Disorders / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology*; D003520:Cyclophosphamide / Q000008:administration & dosage; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009483:Neuropsychological Tests; D017741:Survivors; D013629:Tamoxifen / Q000008:administration & dosage; D014430:Twins, Monozygotic
chemical_list: D001057:Apolipoproteins E; D013629:Tamoxifen; D004317:Doxorubicin; D003520:Cyclophosphamide