Inclusion Criteria:

• Meets the National Institute of Neurological and Communicative Diseases and Stroke/Alzheimers Disease and Related Disorders Association (NINCDS-ADRDA) criteria for Alzheimers disease, regardless of date of diagnosis relative to study entry date.
• Has an Alzheimers disease status of mild to moderate, as classified by a Mini Mental State Examination (MMSE) score of 16 - 26 inclusive at screening.
• Post-menopausal females defined as menopause is defined as >6 months without menstrual period with an appropriate clinical profile, e.g. age appropriate, history of vasomotor symptoms. However if indicated this should be confirmed by oestradiol and FSH levels consistent with menopause (according to local laboratory ranges).
• Women who are on HRT (hormone replacement therapy) treatment, and have not been confirmed as post-menopausal should be advised to use contraception.
• Has a permanent caregiver who is willing to attend all visits, oversee the subjects compliance with protocol-specified procedures and study medication, and report on subjects status. (Subjects living alone or in a nursing home are not eligible).

Exclusion Criteria:

• Has a history of or suffers from claustrophobia.
• Is unable to lie comfortably on a bed inside a PET camera with their head in the field of view for at least 60 minutes as assessed by physical examination and medical history (e.g. back pain, arthritis).
• Has a history or presence of other neurological or other medical conditions that may influence the outcome or analysis of the PET scan results. Examples of such conditions include, but are not limited to stroke, traumatic brain injury, epilepsy or space occupying lesions.
• History of Type I or Type II diabetes mellitus.
• Fasting plasma glucose level >126 mg/dL (>7.0 mmol/L) or HbA1c >6.2%.
• History or clinical/laboratory evidence of moderate congestive heart failure defined by the New York Heart Association criteria (class II-IV.