Developing Brain, Impulsivity and Compulsivity

Study Description:

Many neuropsychiatric disorders have extreme impairing impulsivity and compulsivity behaviors at their core. We hypothesized that the development of symptoms of impulsivity and compulsivity during childhood/adolescence and early adulthood will be associated with atypical trajectories of brain features including cortical glutamate (the main excitatory neurotransmitter) and functional/structural brain connectivity. Additionally, we hypothesize that cortical glutamate will be under genetic control (i.e., heritable) and that common genetic variant risk for disorders characterized by extreme impulsivity (e.g., attention deficit hyperactivity disorder) and by extreme compulsivity (e.g., obsessive compulsive disorder, autism spectrum disorder) will also be associated with atypical cortical glutamate trajectories. To elucidate the relationships between the developing brain, compulsivity/impulsivity and genomics, we will collect clinical assessments including clinician-led interviews, neurobehavioral assessments, neuroimaging data, and genomic samples using 1) a prospective longitudinal design to answer developmental hypotheses; 2) a twin design to assess heritability hypotheses.

Objectives:

Primary Objective:

A) To assess the effects of impulsivity and compulsivity on the developmental trajectories of cortical glutamate.

B) To determine the heritability of cortical glutamate.

Secondary Objectives:

A) To establish the reliability of glutamate measurements.

B) To examine the impact of atypical glutamate levels on developing structural and functional connections within the fronto-striatal circuits.

C) To assess within twin pair differences in neurodevelopmental markers (cortical glutamate, structural/functional MRI) in relation to differences in symptom domains.

Endpoints:

Primary Endpoint:

A) Age-related change in cortical glutamate levels and its moderation by individual differences in levels of impulsivity and compulsivity.

B) Heritability of cortical glutamate (proportion of variance explained by additive genetic factors).

Secondary Endpoints:

A) 1) Glutamate levels estimated at 3 Tesla at short intervals to establish test-retest reliability.

• Glutamate levels estimated at both 3 Tesla and 7 Tesla (cross scanner validation).

B) Measures of the brain's structural and functional connectivity.

C) Within twin-pair differences in neurodevelopmental markers symptom domains (impulsivity/compulsivity).

• INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

• Stated willingness to comply with all study procedures and availability for the duration of the study.
• Must be between 6 and 80 years of age.
• Ability of participant to understand and the willingness to sign a written informed consent document.

Exclusion criteria

An individual who meets any of the following criteria will be excluded from participation in this study:

• Cognitively not capable of performing study procedures or lack of capacity to provide informed consent. Indications of a lack of cognitive capacity could include a known full-scale IQ under 70, or a history from the screening interview that implies global intellectual disabilities (e.g., placement in a school for children with intellectual disability etc.)
• Very premature birth (i.e., birth before 32 weeks of gestational age).
• Any known brain abnormalities (e.g., tumor, periventricular leukomalacia, microcephaly) or history of medical conditions known to affect cerebral anatomy (e.g., epilepsy, history of stroke, head injury with a loss of consciousness of one hour or more).
• Psychotic disorders (including schizophrenia, psychosis not otherwise specified).
• Dementia, or other conditions that, in the opinion of the investigators, would impede compliance or possibly hinder completion of the study.
• Pregnant women.
• Any other medical or psychiatric condition that in the opinion of the PI may confound study data/assessments.

Additional exclusion criteria for optional MRI procedure:

• Individuals who are not able to receive an MRI (e.g., metal bioimplants, claustrophobia, inability to lie flat on their backs, pregnant women, and any other contraindications for MRI scanning according to the NMR Center MRI safety guidelines).