Genetic Influences Between Cognitive Function and BMI

Study Overview
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Brief Summary
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In this study the investigators will interrogate an existing data set to examine whether genetic variants contribute to an inverse association between weight status and cognitive function. Investigators hypothesize that body mass index (BMI) will be inversely related to a number of variables measuring cognitive function, and that that this inverse relation will be at least partially attributable to genetic variants which influence both BMI and cognition.

Detailed Description
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Investigators will use existing data collected as part of the Texas Twin Project (TTP). TTP collected neuropsychological task data on cognition (executive functioning and general cognitive abilities) from a computerized test battery, as well as BMI data, on a sample of 869 twins. Investigators will use information from the known extent of genetic and environmental sharing between members of MZ (monozygotic; identical) and DZ (dizygotic; fraternal) twin pairs to quantify the genetic correlation between measures of cognition and BMI using biometric genetic modeling under the assumptions of the classical twin model. The specific aims are: To examine the association between BMI and executive functioning (EF) in a sample of 869 twin children, ages 7 to 15 years old, who participated in the Texas Twin Project (TTP) To gauge the specificity of EF-BMI relations relative to academic achievement and general cognitive abilities. To examine the relative contribution of genetic and environment influences to the inverse association between BMI and EF

Official Title
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Shared Genetic Influences Between Cognitive Function and Body Mass Index (BMI) in the Texas Twin Project

Conditions
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Obesity

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All participants in the TTP database with executive functioning and BMI data, without a parent-reported medical disorder affecting growth Exclusion Criteria: Parent-reported medical disorder affecting growth More than one sibling in the dataset (if triplets are present, only two randomly selecting siblings will be included).

Ages Eligible for Study
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Minimum Age: 7 Years
Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Executive functioning | This measure will be derived from a computerized test battery incorporating the Animal Stroop, Stop Signal, Mickey (an anti- Trail Making, Local-Global, Plus-Minus, Digit Span Backward, Symmetry Span, Listening Recall, 2-Back, Keeping Track, and Running Memory for Letters tasks. A latent factor of variance common to all these tasks will be used to indicate higher order executive functioning. | 2 hours | 
| Body mass index | Heights and weights were measured by trained study personnel and BMI will be calculated as weight in kilograms (kg) divided by height in centimeters (cm) squared. | 10 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| General Cognitive Ability | This was assessed using the WASI-II | 1 hour | 
| Academic Achievement | This was assessed using the Woodcock-Johnson-III Calculations and Passage Comprehension tests | 30 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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BMI, Obesity, executive functioning, general cognitive ability, twin study, heritability, cognition, GCTA