Dynamic Connectivity Under Metabolic Constraints

Summary

In this study, we investigate the impact of insulin resistance on the acceleration of brain aging, and test whether increased neuron insulin resistance can be counteracted by utilization of alternate metabolic pathways (e.g., ketones rather than glucose). This study has three Arms, which together provide synergistic data. For all three Arms, subjects are tested in a within-subjects design that consists of 2-3 testing sessions, 1-14 days apart, and counter-balanced for order. During each session we measure the impact of fuel (glucose in one session, ketones in the other) on brain metabolism and associated functioning. For Arms 1-2, our primary experimental measure is functional magnetic resonance imaging (fMRI), which we will use to trace the self-organization of functional networks following changes in energy supply and demand. Arm 1 tests the impact of endogenous ketones produced by switching to a low carbohydrate diet, while Arm 2 tests the impact of exogenous ketones consumed as a nutritional supplement. For Arm 3, we use simultaneous magnetic resonance spectroscopy/positron-emission tomography (MR/PET) to quantify the impact of exogenous ketones on production of glutamate and GABA, key neurotransmitters.

Subjects will be given the option to participate in more than one of the Arms, but doing so is not expected nor required.

Prior to scans, subjects will receive a clinician-administered History and Physical (H\&P), which includes vital signs, an oral glucose tolerance test (OGTT), and the comprehensive metabolic blood panel. These will be used to assess diabetes, kidney disease, and electrolytes. If subjects pass screening, they will be provided the option to participate in one or more Arms, which include neuroimaging. To provide a quantitative measure of time-varying metabolic activity throughout the scan, based upon quantitative models of glucose and ketone regulation, as well as to be able to implement safety stopping rules (see below), we will obtain pin-prick blood samples three times: prior to the scan, following consumption of the glucose or ketone drink, and following completion of the scan. To assess effects of increased metabolic demand, we measure brain response to cognitive load, transitioning from resting-state to spatial reasoning through a Tetris task. To assess effects of increased metabolic supply, we measure brain response to glucose or ketone bolus.

Conditions

• Insulin Resistance
• Healthy
• Diet Modification
• Aging

Interventions

DRUG

Ketones

Sports supplement that is administered mid-scan.

DRUG

Glucose

Supplement is administered mid-scan.

Sponsors & Collaborators

• Martinos Center for Biomedical Imaging

  collaborator OTHER

• Massachusetts General Hospital

  lead OTHER

Principal Investigators

• Lilianne Mujica-Parodi, PhD · Stony Brook University

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

79 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-06-19

Primary Completion

2023-09-30

Completion

2023-09-30

FDA Drug

Yes

Countries

• United States

Study Locations