Inclusion Criteria:

1. NIA-Alzheimer's Association core clinical criteria for probable AD

2. Age between 50-90 (inclusive).

3. MMSE score between 16 and 26 (inclusive)

4. Clinical Dementia Rating = 0.5, 1.0, or 2

5. Stability of permitted medications for 4 weeks. In particular, subjects may:

1. Take stable doses of antidepressants (if they are not currently depressed or do
not have a history of major depression within the past 1 year).

2. Washout from psychoactive medication for at least 4 weeks prior to screening.

3. Cholinesterase inhibitors are allowable if stable for 12 weeks prior to screen.

6. Geriatric Depression Scale less than 6.

7. Study partner is available who has frequent contact with the subject (e.g. an average
of 8 hours per week or more), and can accompany the subject to all clinic visits for
the duration of the protocol.

8. Visual and auditory acuity adequate for neuropsychological testing.

9. Good general health with no diseases expected to interfere with the study.

10. Subject is not pregnant, lactating, or of childbearing potential (i.e. women must be
two years post-menopausal or surgically sterile).

11. Modified Hachinski less than or equal to 4.

12. Completed six grades of education or has a good work history (sufficient to exclude
mental retardation).

13. Must speak English or Spanish fluently.

Exclusion Criteria:

1. Any significant neurologic disease other than AD, such as Parkinson's disease,
multi-infarct dementia, Huntington's disease, normal pressure hydrocephalus, brain
tumor, progressive supranuclear palsy, seizure disorder, subdural hematoma, multiple
sclerosis, or history of significant head trauma followed by persistent neurologic
defaults or known structural brain abnormalities

2. Screening/baseline MRI scan with evidence of infection, infarction, or other focal
lesions. Subjects with multiple lacunes or lacunes in a critical memory structure
are excluded.

3. Subjects that have any contraindications for MRI studies, including claustrophobia,
the presence of metal (ferromagnetic) implants, or cardiac pacemaker will be excluded
from the study.

4. Major depression, bipolar disorder as described in DSM-IV within the past 1 year.
Psychotic features, agitation or behavioral problems within 3 months, which could
lead to difficulty complying with the protocol.

5. History of schizophrenia (DSM IV criteria).

6. History of alcohol or substance abuse or dependence within the past 2 years (DSM IV
criteria).

7. Any significant systemic illness or unstable medical condition, which could lead to
difficulty complying with the protocol.

8. Clinically significant abnormalities in B12 or TFTs that might interfere with the
study.

9. Residence in skilled nursing facility.

10. Current use (within 30 days of screening) of specific psychoactive medications (e.g.,
typical neuroleptics, narcotic analgesics, antiparkinsonian medications, systemic
corticosteroids, or medications with significant central anticholinergic activity,
etc.). Current use of warfarin.

11. Investigational amyloid lowering therapies are prohibited two months prior to
screening and for the duration of the trial. Other investigational agents are
prohibited one month prior to screening and for the duration of the trial.

12. Current or recent participation in any procedures involving radioactive agents,
including current, past, or anticipated exposure to radiation in the workplace, such
that the total radiation dose exposure to the subject in a given year would exceed
the limits of annual and total dose commitment set forth in the US Code of Federal
Regulations (CFR) Title 21 Section 361.1. This guideline is an effective dose of 5
rem received per year.

13. Current use of the following medications (CYP3A4 substrates whose metabolism may be
slowed by AZD0530): carbamazepine, colchicine, cyclosporine, disopyramide,
fluticasone, quinidine, vinblastine, vincristine. Patients taking sildenafil,
tadalafil, and vardenafil will be advised to stop taking these medications for the
duration of the trial.

14. Neutropenia defined as absolute neutrophils count of <1,500/microliter.

15. Thrombocytopenia defined as platelet count <100x103/microliter.