title: Brain-derived neurotrophic factor Val⁶⁶Met polymorphism affects resting regional cerebral blood flow and functional connectivity differentially in women versus men.
abstract: The human Val⁶⁶Met single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene impacts BDNF signaling at the cellular level. At the neural-systems level, it is associated with differences in prefrontal cortex (PFC) and hippocampal function during performance of cognitive and affective tasks. Because the impact of this variant on basal prefrontal and hippocampal activity is not known but may be relevant to understanding the function of this gene in health and disease, we studied 94 healthy individuals with H₂ ¹⁵O PET to assess regional cerebral blood flow (rCBF) during rest and tested for between-genotype differences. Because BDNF and gonadal steroid hormones conjointly influence neuronal growth, survival, and plasticity in hippocampus and PFC, we also tested for sex × genotype interactions. Finally, in light of the known impact of BDNF on plasticity and dendritic arborization, we complimented direct rCBF comparisons with connectivity analyses to determine how activity in hippocampal and prefrontal regions showing between-genotype group differences covaries with rCBF in other nodes throughout the brain in a genotype- or sex-dependent manner. Compared with Val homozygotes, Met carriers had higher rCBF in prefrontal (BA25 extending into BA10) and hippocampal/parahippocampal regions. Moreover, there were significant sex × genotype interactions in regions (including frontal, parahippocampal, and lateral temporal cortex) in which Val homozygotes showed higher rCBF in females than males, but Met carriers showed the opposite relationship. Functional connectivity analysis demonstrated that correlations of BA25, hippocampus, and parahippocampus with frontal and temporal networks were positive for Val homozygotes and negative for Met carriers. In addition, sex × genotype analysis of functional connectivity revealed that genotype affected directionality of the inter-regional correlations differentially in men versus women. Our data indicate that BDNF allelic variation and sex interactively affect basal prefrontal and hippocampal function.
authors.affiliation: Section on Integrative Neuroimaging, National Institute of Mental Health Intramural Research Programs, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Shau-Ming
authors.initials: SM
authors.lastname: Wei
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Eisenberg
authors.forename: Philip D
authors.initials: PD
authors.lastname: Kohn
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Kippenhan
authors.forename: Bhaskar S
authors.initials: BS
authors.lastname: Kolachana
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Weinberger
authors.forename: Karen F
authors.initials: KF
authors.lastname: Berman
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000235:genetics / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods; D005838:Genotype; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000502:physiology; D010104:Oxygen Radioisotopes; D020641:Polymorphism, Single Nucleotide; D049268:Positron-Emission Tomography / Q000379:methods; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D012727:Sex Characteristics; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000502:physiology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D010104:Oxygen Radioisotopes