title: Genetic influences on hippocampal volume differ as a function of testosterone level in middle-aged men.
abstract: The hippocampus expresses a large number of androgen receptors; therefore, in men it is potentially vulnerable to the gradual age-related decline of testosterone levels. In the present study we sought to elucidate the nature of the relationship between testosterone and hippocampal volume in a sample of middle-aged male twins (average age 55.8 years). We found no evidence for a correlation between testosterone level and hippocampal volume, as well as no indication of shared genetic influences. However, a significant moderating effect of testosterone on the genetic and environmental determinants of hippocampal volume was observed. Genetic influences on hippocampal volume increased substantially as a function of increasing testosterone level, while environmental influences either decreased or remained stable. These findings provide evidence for an apparent gene-by-hormone interaction on hippocampal volume. To the best of our knowledge, this is the first study to demonstrate that the heritability of a brain structure in adults may be modified by an endogenous biological factor.
authors: Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA. mspanizz@ucsd.edu
authors: Matthew S
authors: MS
authors: Panizzon
authors: Richard L
authors: RL
authors: Hauger
authors: Lindon J
authors: LJ
authors: Eaves
authors: Chi-Hua
authors: CH
authors: Chen
authors: Anders M
authors: AM
authors: Dale
authors: Lisa T
authors: LT
authors: Eyler
authors: Bruce
authors: B
authors: Fischl
authors: Christine
authors: C
authors: Fennema-Notestine
authors: Carol E
authors: CE
authors: Franz
authors: Michael D
authors: MD
authors: Grant
authors: Kristen C
authors: KC
authors: Jacobson
authors: Amy J
authors: AJ
authors: Jak
authors: Michael J
authors: MJ
authors: Lyons
authors: Sally P
authors: SP
authors: Mendoza
authors: Michael C
authors: MC
authors: Neale
authors: Elizabeth
authors: E
authors: Prom-Wormley
authors: Larry J
authors: LJ
authors: Seidman
authors: Ming T
authors: MT
authors: Tsuang
authors: Hong
authors: H
authors: Xian
authors: William S
authors: WS
authors: Kremen
mesh_terms: D006624:Hippocampus / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology; D013739:Testosterone / Q000097:blood*; D014427:Twins / Q000235:genetics*
chemical_list: D013739:Testosterone