Vascular nitric oxide may lessen Alzheimer's risk

Estrogen deficiency, hyperinsulinemia, type II diabetes, atherosclerosis, and a past history of elevated blood pressure may be associated with increased risk of Alzheimer's disease (AD). Common to all of these risk factors is a diminished capacity of vascular endothelium to generate nitric oxide (NO). Vascular NO has the potential to enhance the membrane polarization of cerebral neurons by increasing the open probability of calcium-activated potassium channels; this may protect neurons from the excessive calcium influx, potentiated by beta-amyloid peptides that is thought to mediate neuronal damage in AD. The possibility that NO/cyclic guanosine 3', 5'-phosphate (cGMP) may modulate the synthesis or processing of the amyloid precursor protein, also merits evaluation. Practical measures for promoting vascular NO production may include increased intakes of arginine, potassium, antioxidants, and fish-oil, as well as lifestyle measures that typically lower elevated blood pressure; potential benefits of chromium, glucosamine, and silicon should also be explored. In hypertensives, angiotensin-converting enzyme (ACE) inhibitors and sodium restriction may favorably influence endothelial function. Fish-oil should have the additional benefit of antagonizing the contribution of interleukin-1 to AD pathogenesis. Ancillary anti-excitotoxic measures such as magnesium, taurine, phenytoin, and vasodilators targeting ATP-dependent potassium (KATP) channels, may likewise reduce AD risk. Most of the nutritional measures suggested here would in any case be recommendable for preservation of vascular health.