Iontophoretic study of adrenergic and cholinergic skin vessel reactivity in normal ageing and Alzheimer's disease.

Iontophoresis was used to evaluate the peripheral reactivity of phenylephrine (alpha 1-agonist), isoproterenol (beta-agonist) and metacholine (cholinergic agonist) in patients with Alzheimer's disease (AD). The cutaneous responses--erythema and blanching--were visually recorded. Healthy personnel, medical students and patients with various dermatoses served as controls. A reduced response towards the adrenergic agonists was seen in AD. The reduced sensitivity was highly significant for the beta-agonist isoproterenol (p less than 0.001), in contradistinction the metacholine response did not differ between AD and age-matched controls. Furthermore, increasing age did not seem to significantly influence the cutaneous responses in mentally healthy controls. Thus, a reduced peripheral adrenergic reactivity was observed in the patients suffering from AD.