Inclusion criteria:
Diagnoses of possible or probable Alzheimer's disease (NINCDS-ADRDA).
Presence of a caregiver (friend or relative) who can assume responsibility for medication administrations, accompany the patient to all visits, and rate patient's condition.
Written informed consent from both the patient (or surrogate) and caregiver.
An MMSE score between 12 and 26 inclusive.
Administration of a maintenance dosage of donepezil (5-10mg/d), rivastigmine (3-6mg/d), galantamine or galantamine ER (8-16mg/d) for a minimum of 4 weeks prior to randomization.
Agreement not to take Hydralazine.
Age 49 and over
Exclusion criteria:
A non-Alzheimer primary dementia (e.g., vascular dementia, Lewy body dementia, frontotemporal dementia, vitamin B-12 deficiency, hypothyroidism).
Current major depression, delirium, alcohol or psychoactive substance abuse or dependency, schizophrenia, or delusional disorder as defined by DSM-IV.
Presence of any uncontrolled systemic illness that would interfere with participation in the study or a life expectancy of less than one year.
Currently being treated with Hydralazine or a history of intolerance to oral therapy with Hydralazine
Any intravenous treatment for heart failure, except IV furosemide (e.g. IV inotropes, pressors, nitrates or nesiritide) at the time of screening.
Systolic blood pressure <100 mmHg
Reversible etiology of acute heart failure such as myocarditis, acute myocardial infarction-over the past 4 weeks, arrhythmia and pacing device (Acute MI is defined as symptoms and major electrocardiogram (ECG) changes(i.e., ST segment elevations), and arrhythmia includes unstable heart rates above 120/min or below 50/min).
Known severe congenital heart disease (such as uncorrected tetralogy of fallot or transposition of the aorta) and severe aortic or mitral stenosis or severe rheumatic mitral regurgitation.
Concurrent use of phosphodiesterase type 5 (PDE5) inhibitors (e.g. Viagra, Sildenafil. Etc.)
Have had cardiac revascularisation within the last 3 months or are likely to require coronary revascularisation within the study period.
eGFR< 15ml/min/1.73m2, or on regular dialysis, or planned dialysis within the study period