Choline Dose Ranging in Postmenopausal Women

This study will use a randomized placebo-controlled trial to examine smaller doses of choline and whether a signal in the brain is detectable using fMRI. This study will examine if an even smaller doses of choline can show these similar brain activation and connectivity patterns to the 1650 mg dose. This will be a dose ranging study of 550 mg and 1100 mg oral choline compared to placebo.

Inclusion Criteria: * Women aged 50-65 years * Postmenopausal: Women who are postmenopausal will have not had a period in the last 12 months, have FSH\>30 IU/L, and estradiol (E2) \80 * Normal neuropsychological test performance Exclusion Criteria: * MCI or dementia - Montreal Cognitive Assessment \ 160/100 (untreated) * Untreated thyroid disease * Significant cardiovascular disease * Asthma or COPD * Active peptic ulcer * Hyperthyroidism * Epilepsy * Current untreated or unremitted Axis I psychiatric disorders Use of medications on the Prohibited medications (see list)