An Early Phase 1 interventional study of Glycine and N-acetylcysteine in Alzheimer Disease, sponsored by Baylor College of Medicine. Active, not recruiting at 1 site in United States. Open to participants aged 55 Years to 85 Years. Per ClinicalTrials.gov, last updated 2026-09-09.
Sponsored by Baylor College of Medicine · Early Phase 1, Interventional, and Other
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.
3,678 studies on the registry are indexed under Alzheimer Disease; 872 are open to participants now.
This study's planned enrollment of 52 is below the median of 70 across 2,808 interventional studies indexed under Alzheimer Disease.
Browse Alzheimer Disease studies →Baylor College of Medicine is the lead sponsor of 734 studies on the registry; 110 are open to participants now.
Of its 83 completed or terminated interventional studies of FDA-regulated products, 44 (53%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Glycine and cysteine are amino-acid (protein) precursors of glutathione. Cysteine is provided as N-acetylcysteine
Dietary Supplement: Glycine · Dietary Supplement: N-acetylcysteine
Alanine is an amino-acid (protein), and not a precursor of glutathione synthesis
Dietary Supplement: Alanine
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
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
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
Plan to share: No
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This study is active, not recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Baylor College of Medicine