The purpose of this study is to examine the effects of supplementing Magnesium L-Threonate in people with mild to moderate dementia. The investigators' goal is to understand whether Magnesium L-Threonate will be associated with improvement in memory and brain function.

Emerging research on the effects of a novel magnesium compound of L-Threonic Acid Magnesium Salt (L-TAMS) containing Vitamins C and D on cognitive performance suggests that supplementation may benefit individuals with Alzheimer's disease (AD). This proof of concept will assess whether supplementation with Magtein (MGT), a constant release formula of Magnesium L-threonate, Vitamin C, and Vitamin D, is associated with changes in regional cerebral metabolism in elderly people with mild to moderate dementia.

This is an open-label, two-month trial consisting of 15-20 participants aged 60 and older with mild to moderate dementia. Subjects will receive 1,800 mg/day of MgT-1219 for a total of 60 days. They will be given neurocognitive testing, blood chemistries, and FDG-PET imaging at baseline, 60 days and more testing at 180 days to assess the acute effect of MgT-1219 on hippocampal and PFC-mediated executive function, attention, reasoning, and memory. Blood draws will be conducted prior to treatment initiation to assess kidney and liver function, complete blood count, fasting plasma insulin, and red blood cell magnesium.

Our outcome measures include a combination of neuropsychological testing and neuroimaging. These will be employed to measure changes in the degree of cognitive impairment within subjects over time, as well as between subjects in the intervention and control groups. FDG-PET imaging will be used to assess the degree of synaptic activity and density within subjects at different time points in the study. These measures will be supplemented by measures of, sleep quality, daytime sleepiness, depression, and activities of daily living.

Inclusion Criteria:

• People of either gender > 60 years of age.
• Subject scores between 16 and 26 on the MMSE
• Subject or representative is willing to sign the consent for prior to enrollment into the study and to participate in all aspects of the study. Prospective subject must give verbal assent if unable to sign written consent.
• Adequate visual and auditory acuity to allow neuropsychological testing.
• Greater than 12 years of educational achievement, or a General Education Development certificate to allow adequate neuropsychological testing, and consistency of sample.
• Female subject is surgically sterile, post-menopausal or agrees to use an acceptable method of birth control.
• Subject agrees to stop taking any vitamins, minerals, or dietary/herbal supplements he/she is currently taking at least 7 days prior to randomization and agrees to not take any vitamins, minerals or dietary/herbal supplements other than the study product until after study completion.

Exclusion Criteria:

• Active heart disease
• Uncontrolled high blood pressure (≥ 140/90 mmHg)
• Renal or hepatic impairment/disease
• Type I diabetes
• Unstable thyroid disease
• Psychiatric disorder (hospitalized in the past year)
• History of drug or alcohol abuse.
• Immune disorder (such as HIV/AIDS)
• TIAs, carotid bruits, or verified lacunes
• Significant pulmonary disease
• Contraindication for a PET scan including those who have had a stroke or heart attack in the past 6 months, and those unable or unwilling to lie down for 1 hour.
• Any medical condition deemed exclusionary by the Principal Investigator (PI)
• History of cancer (except localized skin cancer without metastases or in situ cervical cancer) within 5 years prior to screening.
• Currently taking any medications that are known to interact with magnesium.
• Currently taking antibiotics as the study product may reduce the absorption of antibiotics. A washout period of 2 weeks is allowed.
• On an unstable dose of medication (defined as fewer than 90 days at the same dose).
• Currently taking any medication deemed exclusionary by PI.
• Allergy or sensitivity to any ingredient in the test product.
• Evidence of hepatic or renal dysfunction
• History of drug or alcohol abuse in the past 12 months.
• Pregnant , lactating, or planning to become pregnant during the study period.
• Subject has any condition or abnormality that, in the opinion of the investigator, would compromise the safety of the subject or the quality of the study data.
• Subject is participating or has participated in another research study within 30 days prior to the screening visit.