The PLasma for Alzheimer SymptoM Amelioration (PLASMA) Study

Inclusion Criteria: * Diagnosis of probable Alzheimer's disease (NIA-AA criteria) * Mini-Mental State Examination (MMSE) score 12-24 * Availability of a study partner who knows the patient well and is willing to accompany the subject to all trial visits, to participate in questionnaires and to complete daily journal assessments Exclusion Criteria: * Pregnancy or unwilling to use adequate birth control method for duration of and 6 months beyond study participation * Positive for Hepatitis B, Hepatitis C or HIV at screening * Any other condition or situation that the investigator believes may interfere with the safety of the subject or the intent and conduct of the study * Related to medical history: * Stroke * Anaphylaxis * Prior adverse reaction to any human blood product * Any history of a blood coagulation disorder or hypercoagulability * Congestive heart failure * Uncontrolled hypertension * Renal failure * Prior intolerance to intravenous fluids * Recent history of uncontrolled atrial fibrillation * IgA deficiency (by history) * Related to medications or other treatments: * Any concurrent use of an anticoagulant therapy. Antiplatelet drugs (e.g., aspirin or clopidogrel) are acceptable * Initiation or change in the dosage of a cholinesterase inhibitor or memantine during the trial. A participant already on a cholinesterase inhibitor or memantine must be on a stable dose for at least one month prior to Screening * Concurrent participation in another treatment trial for Alzheimer's disease. If there was prior participation, the last dose of the investigational agent must have been at least 6 months prior to Screening * Treatment with any human blood product, including intravenous immunoglobulin, during the 6 months prior to Screening or during the trial * Concurrent daily treatment with benzodiazepines, typical or atypical antipsychotics, long-acting opioids, or other medications that, in the investigator's opinion, interfere with cognition. Intermittent treatment with short-acting benzodiazepines or atypical antipsychotics may be permitted, provided that no dose is administered within the 72 hours preceding any cognitive assessment * Related to magnetic resonance imaging: * Claustrophobia * Any metallic surgical implant, like a pacemaker or clip that is incompatible with 3T MRI. Certain metallic implants like joint replacements may be permitted, provided that specific manufacturer specifications are available and that the device is known to be safe for 3T MRI.