title: Longitudinal genetic analysis of brain volumes in normal elderly male twins.
abstract: This study investigated the role of genetic and environmental influences on individual differences in brain volumes measured at 2 time points in normal elderly males from the National Heart, Lung, and Blood Institute Twin Study. The magnetic resonance imaging (MRI) scans were conducted 4 years apart on 33 monozygotic and 33 dizygotic male twin pairs, aged 68 to 77 years when first scanned. Volumetric measures of total brain and total cerebrospinal fluid were significantly heritable at baseline (over 70%). For both volumes genetic influences at follow-up were entirely accounted for by genetic influences at baseline, suggesting that the same genetic factors influence variability in brain volume at each time of assessment. Variability in 4-year volume change was due to shared and individual-specific environmental influences. There was little evidence for heritable influences on change measures. These results suggest that variation in longitudinal change of some brain volume measures may have different underlying genetic and environmental architecture from variation in repeat cross-sectional measures, which could have implications for intervention strategies for age-related illness associated with brain morphology. The results of this study are discussed in the context of the small sample size and associated limitations of statistical power.
authors.affiliation: Center for Health Sciences, SRI International, Menlo Park, CA, USA. schlaggc@psychiatry.wustl.edu
authors.forename: Christina N
authors.initials: CN
authors.lastname: Lessov-Schlaggar
authors.forename: Jill
authors.initials: J
authors.lastname: Hardin
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Krasnow
authors.forename: Terry
authors.initials: T
authors.lastname: Reed
authors.forename: Philip A
authors.initials: PA
authors.lastname: Wolf
authors.forename: Gary E
authors.initials: GE
authors.lastname: Swan
authors.forename: Dorit
authors.initials: D
authors.lastname: Carmelli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics*; D000704:Analysis of Variance; D001921:Brain / Q000033:anatomy & histology*; D016009:Chi-Square Distribution; D004777:Environment; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D054555:National Heart, Lung, and Blood Institute (U.S.); D012189:Retrospective Studies; D014427:Twins / Q000235:genetics*; D014481:United States