Browsing by Subject "twins"

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    Does substance use during youth cause lasting changes in resting-state neurophysiology and brain functional connectivity? A co-twin control investigation
    (2017-08) Burwell, Scott
    This dissertation comprises two studies aimed at disentangling potential causal effects of recreational substance use (alcohol, cannabis, tobacco) on resting-state electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) brain outcomes in a community sample of young adults. As noted by the introductory text for each study, there is a dearth of causally-informative research designs in published literature regarding whether drug and alcohol use has lasting effects on human EEG and fMRI. These two studies intend to bridge this gap by utilizing a causally-informative co-twin control (CTC) research design which utilizes the fact that twins reared in the same home are matched on many factors (e.g., genes, parental substance use, SES) that contribute to confounding in the hypothetical causal link between substance use and brain outcomes in extant cross-sectional research. As such, within twin-pair differences in use can be exploited to study within twin-pair differences in brain outcome (e.g., EEG, fMRI) to understand possible causal effects.
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    Twice as Nice or Double Trouble: Examination of IVF Twins relative to IVF Singletons and their Families' Outcomes in Adolescence
    (2016-04) Anderson, Kayla
    The two presented studies examine outcomes of in vitro fertilization (IVF)-conceived twins relative to IVF singletons and their families in adolescence (Study 1: n = 194 families, Study 2: n = 192 families). Study 1 used nested ANCOVAs to examine differences in family environment and adolescent adjustment outcomes among 11 – 17 year-old IVF twins and IVF singletons and their families. Despite notable statistical power, there were no differences between adolescent-aged IVF twins and IVF singletons and their families. This suggests IVF twins and their families function well into adolescence. Study 2 tested two autoregressive path models that propose parental conformity expectations have differential effects on twins’ and singletons’ parent-adolescent relationship satisfaction, which indirectly accounts for relative changes in twins’ and singletons’ adjustment over time. Despite the developmental need for increased autonomy in adolescence, results indicate high conformity expectations play a positive role for adolescent-aged twins and their families. These studies suggest that, while adolescent IVF twins and IVF singletons and their families function well, research on singletons should not be universally applied to understand twins and their families.