Alzheimer's disease (AD) is associated with significant, progressive cognitive decline. Key defects in mitochondrial fuel metabolism insulin resistance, inflammation and decreased brain glucose uptake are linked to AD. This trial will investigate the effects of supplementing glycine and N-acetylcysteine vs. alanine as placebo on these defects in AD, and examine the effects on cognition.
Glutathione (GSH) deficiency, oxidative stress, mitochondrial dysfunction, insulin resistance and inflammation are linked to Alzheimer's disease (AD). In prior studies, investigators have shown that GSH deficiency contributes to mitochondrial impairment and oxidative stress, and that GSH deficiency can be corrected by supplementing its precursors glycine and cysteine (provided as N-acetylcysteine, NAC), with the combination termed GlyNAC. This randomized clinical trial will evaluate the effect of GlyNAC vs. alanine placebo supplementation provided for 24-weeks to patients with AD, and measure changes in cognition, GSH concentrations, oxidative stress, brain glucose uptake, brain inflammation and insulin resistance. Participants who are positive for a beta-amyloid PET scan and meeting cognitive screening criteria will be recruited, and enrolled only after meeting eligibility criteria. Before beginning study supplementation they will undergo imaging studies (MRI, FDG-PET and TSPO-PET scans), and only the FDG- and TSPO-PET scans will be repeated after completing 24-weeks of nutrient supplementation. Cognitive measurements, metabolic and mitochondrial measurements (as described below) will be done before supplementation, and after 12-weeks and 24-weeks of completing supplementation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
52
The active arm will supplement a combination of glycine and N-acetylcysteine (GlyNAC)
The active arm will supplement a combination of glycine and N-acetylcysteine (GlyNAC)
The placebo arm will supplement Alanine
Baylor College of Medicine
Houston, Texas, United States
Cognition
Measured using ADAS-Cog testing
Time frame: Day 0 of supplementation, and 12-weeks and 24-weeks after starting supplementation
Brain glucose uptake
Measured using brain FDG-PET scan
Time frame: Done before supplementation and 24-weeks after starting supplementation
Brain inflammation
Done using brain TSPO-PET scan
Time frame: Done before supplementation and 24-weeks after starting supplementation
Activities of daily living
Measured using the ADCS-ADL scale
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Mitochondrial fuel oxidation
Measured using indirect calorimetry in the fasted and post-glucose fed state
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Red-blood cell glutathione, glycine, cysteine and glutamic aid
Measured using UPLC
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Oxidative stress
Measured as plasma concentrations of TBARS and malondialdehyde
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Damage due to oxidative stress
Measured as plasma concentration of isoprostanes
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Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Inflammatory cytokines
Measured as plasma concentrations of IL6, TNFa
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Endothelial dysfunction
Measured as plasma concentrations of sICAM1, sVCAM1, E-selectin
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Plasma concentration of Brain-derived neurotropic factor (BDNF)
Measured using an ELISA kit
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation
Mitochondrial energetics
Measured using the Oroboros high-resolution respirometer
Time frame: Day 0 of supplementation, 12-weeks and 24-weeks after starting supplementation