Early Brain Development in Twins

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to study the role of genes and environment in early brain development using a twin approach. The investigators will use magnetic resonance imaging (MRI) to study brain structure and it's relationship to cognitive development. Specifically, the investigators will study cortical gray and white matter volumes, volumes of subcortical structures and cerebellum, as well as diffusion properties in major white matter tracts using DTI tractography.

Detailed Description
-----------------
Twin studies have been critical in determining the contributions of genetic and environmental factors to normal brain structure and for understanding abnormalities of brain development that underlie neurodevelopmental and neuropsychiatric disorders. In adults and older children, twin studies indicate that genes play a significant role in the variability of global brain volumes, including total brain, total gray and total white matter volumes. Other than this current study, there have been no studies of twin brain development in early childhood, the period of brain development implicated in the pathogenesis of many psychiatric disorders. In the first funding cycle of this grant, the investigators used prenatal ultrasound and neonatal MRI to study discordance of early brain development, and to determine genetic and environmental contributions to neonatal brain structure. The investigators have and have developed a unique and valuable cohort of twins, having recruited and scanned over 100 twin pairs. The investigators found that discordance of prenatal brain size in MZ twins is similar to that in DZ twins, but that by 1 month after birth, discordance of overall brain volume in MZ twins is already less than in DZ twins. Contrary to our original hypothesis, statistical modeling of neonatal MRI brain volumes in our twin cohort indicates that global tissue volumes are highly heritable, similar to that observed in older children and adults. Therefore, it appears that genetic programs act very early in postnatal brain development to determine global tissue volumes. Interestingly, preliminary longitudinal mapping of correlations in gray matter density indicate correlations decrease in the first year of life, perhaps as the result of rapid brain growth in the first years of life. The investigators also found that while global white matter volumes are highly heritable, diffusion tensor properties of specific white matter tracts are not. In the next funding cycle, the investigators propose to continue enlarging this unique cohort and to follow them through age 6 years with structural MRI, diffusion tensor imaging (DTI), and developmental assessments to determine how genetic and environmental factors contribute to brain development in the first years of life.

Official Title
-----------------
Early Brain Development in Twins

Conditions
-----------------
Twin Brain Development

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: twins Exclusion Criteria: major medical, obstetrical or neurological complications

Ages Eligible for Study
-----------------
Maximum Age: 6 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| twins<br>twin pairs | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain Gray Matter Volume | Will assess gray matter volume with MRI and use structural equation modeling to determine relative contributions of genes and environment to variation of gray matter volumes. | Change in heritability from birth to age 6 years | 
| Brain white matter tract integrity | Will assess white matter tract development and integrity using diffusion tensor imaging and will determine relative contributions of genes and environment ot this using twin methodology. | Change in heritability from birth to age 6 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mullen composite Score | Will assess genetic and environmental contributions to early cognitive development using a twin methodology | 1,2,4,6 years | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
twin, brain development, MRI