Alzheimer's disease is a devastating neurodegenerative disorder, for which there is currently no effective treatment to slow or halt progression. Beta amyloid peptide accumulates in the brains of those with Alzheimer's, and is thought to play a major role in triggering the dementia. The investigators recently characterized a molecular pathway by which ß-amyloid damages neurons, and showed that the protein termed Fyn kinase is crucial. Our data suggest that blocking Fyn will have a significant therapeutic benefit for Alzheimer's. Astra Zeneca has developed a blocker of Fyn and related kinases (AZD0530) for the treatment of cancer. Chronic AZD0530 administration is well tolerated in humans, and the investigators propose to test its potential as a novel Alzheimer's disease modifying therapy. This study will assess the safety and tolerability of AZD0530 in patients with Alzheimer's disease.

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.

   7. Clinically significant or unstable medical condition, including uncontrolled hypertension, uncontrolled diabetes, or significant cardiac, pulmonary, renal, hepatic, endocrine, or other systemic disease in the opinion of the Investigator, may either put the patient at risk because of participation in the study, or influence the results, or the patient's ability to participate in the study.

   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 (within 30 days of screening and throughout the protocol including the 2 week follow-up period) of the following medications: a) strong CYP3A4 inhibitors including: atazanavir, indinavir, ritonavir, saquinavir, nelfinavir, ketoconazole, itraconazole, clarithromycin, telithromycin, and nefazodone; b) strong CYP3A4 including: rifampicin, phenytoin, phenobarbital, and carbamazepine; c) certain CYP3A4 substrates including 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. 16. Current blood clotting or bleeding disorder, or significantly abnormal PT or PTT at screening.

   17. Clinically significant abnormalities in screening laboratories, including Aspartate aminotransferase (AST) >1.5 times ULN; Alanine aminotransferase (ALT) > 1.5 times ULN; Total bilirubin >1.5 times ULN; Serum creatinine >2.0 times ULN.

   18. History of interstitial lung disease.