The GLUCID Study: Effect of Alcohol Reduction and Probiotic Interventions on Cognition and Brain Glucose Metabolism in Normal Aging Adults Who Are High-Risk Alcohol Drinkers

Inclusion Criteria:

* Between 65 and 84 years of age
* English speaking
* Able to provide valid informed consent, understand requirement and risk/benefits of the study and comply with study protocol
* Heavy drinker defined as \>14 alcoholic drinks/week for men and \>7 drinks/week for women
* Interested in reducing their alcohol consumption

Exclusion Criteria:

* BMI ≥ 35
* Fasting Glucose \> 125 mg/dL
* Current or previously diagnosed with Type 1 or 2 Diabetes
* Requires the use of insulin and/or other glucose lowering agents
* Unable to fast for 12 hours
* Past serious alcohol withdrawal symptoms
* MRI Contraindications (e.g., certain devices and implants, claustrophobic)
* Diagnosed with a neurodegenerative disease (e.g., Alzheimer's Disease)
* Diagnosed with a psychotic disorder
* Current substance dependence diagnosis (except for mild or moderate alcohol)
* Consumption of over 300 drinks in the past 30 days
* Current probiotic use or recent probiotic use within the past 30 days
* Current antibiotic use or recent antibiotic use within the past 30 days
* In active cancer treatment and/or have advanced cancer
* Taking daily steroids and/or immunosuppressants
* Lifetime organ or bone marrow transplant; primary immunodeficiency (e.g., DiGeorge syndrome or Wiskott-Aldrich syndrome) or transplant recipient or prescribed immunosuppressant medications
* PI's discretion