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Morphological changes in aging brain structures are differentially affected by time-linked environmental influences
Adolf Pfefferbaum1, Edith V Sullivan, Dorit Carmelli
1Neuroscience Program, SRI International, Center for Health Sciences (BN 115), 333 Ravenswood Street, Menlo Park, CA 94025, USA. dolf@synapse.sri.com
Neurobiology of Aging
|January 30, 2004
Summary
Genetic factors significantly influence brain structure size in elderly men, with heritability remaining stable over time. New environmental factors emerge, impacting brain morphology and ventricular volume changes.
Area of Science:
- Neuroscience
- Behavioral Genetics
- Aging Research
Background:
- Individual differences in brain structure morphology, specifically the corpus callosum and lateral ventricles, are significant in aging.
- Understanding the genetic and environmental contributions to these changes is crucial for aging research.
Purpose of the Study:
- To estimate the change and stability of genetic contributions to the morphology of the corpus callosum and lateral ventricles using a longitudinal twin model.
- To investigate genetic and environmental influences on brain structure changes in elderly males over a 4-year period.
Main Methods:
- Longitudinal study of 142 elderly male twin pairs (34 monozygotic, 37 dizygotic) from the NHLBI Twin Study.
- Brain magnetic resonance imaging (MRI) conducted at two time points, 4 years apart.
- Application of the full twin model for genetic and environmental variance estimation, including bivariate genetic analysis.
Main Results:
- Genetic factors substantially accounted for individual differences in corpus callosum and lateral ventricular size.
- Heritability estimates for these brain structures remained stable over the 4-year interval.
- New environmental variance emerged for both callosal and ventricular measures over time, with significant genetic correlation between changes in corpus callosum height and ventricular volume.
Conclusions:
- Genetic influences on corpus callosum and lateral ventricle morphology are stable into old age.
- Environmental factors play a role in the longitudinal changes of these brain structures.
- Genetic variance in callosal height change is linked to genes influencing ventricular expansion, challenging aging hypotheses based on random DNA damage.