title: Regional gray matter reductions are associated with genetic liability for anxiety and depression: an MRI twin study.
abstract: BACKGROUND
  The influence of genetic and/or environmental factors on the volumetric brain changes observed in subjects affected by anxiety and depression disorders remains unclear. The current study aimed to investigate whether genetic and environmental liabilities make different contributions to abnormalities in gray matter volume (GMV) in anxiety and depression using a concordant and discordant MZ twin pairs design.
  
  
  METHODS
  Fifty-three magnetic resonance imaging (3T) brain scans were obtained from monozygotic (MZ) twins concordant (6 pairs) and discordant (10 pairs) for lifetime anxiety and depression disorders and from healthy twins (21 subjects). We applied voxel-based morphometry to analyse GMV differences. Concordant affected twins were compared to healthy twins and within-pairs comparisons were performed in the discordant group.
  
  
  RESULTS
  GMV reductions in bilateral fusiform gyrus and amygdala were observed in concordant affected twins for anxiety and depression compared to healthy twins. No intrapair differences were found in GMV between discordant affected twins and their healthy co-twins.
  
  
  CONCLUSIONS
  The sample size was modest. This might explain why no intrapair differences were found in the discordant MZ twin group.
  
  
  CONCLUSIONS
  As concordant affected MZ twins are believed to have a particularly high genetic liability for the disorder, our findings suggest that fusiform gyrus and amygdala gray matter reductions are related to a genetic risk for anxiety and depression. Discrepancies in regard to brain abnormalities in anxiety and depression may be related to the admixture of patients with GMV abnormalities mainly accounted for by genetic factors with patients presenting GMV mainly accounted for by environmental factors.
authors: Unidad de Antropología, Departamento de Biología Animal, Facultad de Biología and Instituto de Biomedicina, Universidad de Barcelona, Barcelona, Spain. silvia.alemany@ub.edu
authors: Silvia
authors: S
authors: Alemany
authors: Alex
authors: A
authors: Mas
authors: Ximena
authors: X
authors: Goldberg
authors: Carles
authors: C
authors: Falcón
authors: Mar
authors: M
authors: Fatjó-Vilas
authors: Bárbara
authors: B
authors: Arias
authors: Núria
authors: N
authors: Bargalló
authors: Igor
authors: I
authors: Nenadic
authors: Cristóbal
authors: C
authors: Gastó
authors: Lourdes
authors: L
authors: Fañanás
mesh_terms: D000328:Adult; D000679:Amygdala / Q000473:pathology*; D001008:Anxiety Disorders / Q000235:genetics / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology*; D003865:Major Depressive Disorder / Q000235:genetics / Q000473:pathology*; D004200:Diseases in Twins / Q000473:pathology / Q000523:psychology*; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014430:Twins, Monozygotic / Q000523:psychology