Migraine headaches usually decrease in frequency and severity and often cease during advancing age. Occasionally, migraineurs report late-life migrainous accompaniments, i.e., auras without headache, particularly when typical migraine attacks terminate or diminish following major or minor strokes, at which time the auras may become atypical. Clinical observations such as these suggest that degenerative cerebrovascular changes accompanying aging may modify the course of migraine headaches particularly those with aura. To test this hypothesis, we quantitated age-related changes in cerebral vasodilator capacitance by measuring local cerebral blood flow utilizing xenon contrast computed tomography (CT) scanning before and after oral administration of the pharmacological cerebral vasodilator, acetazolamide (Diamox). Measurements were compared among 27 normal volunteers without headache (aged 24-94 years; mean age 61.1 +/- 17.6) and 37 carefully categorized groups of migraine patients (aged 27-83 years; mean age 59.4 +/- 12.4). The normals comprised Group A. Migraineurs were divided into two subgroups: Group B consisted of 27 migraineurs with and without aura who continued to suffer from incapacitating and frequent headaches and Group C consisted of 10 migraineurs who no longer suffered from severe and frequent headaches, two of whom still complained of atypical auras of the "late-life migrainous accompaniments" type. Cerebral vasodilator capacitance significantly declined with advancing age among normals and the two groups of migraineurs, confirming the development of age-related cerebrovascular diseases. Global CBF increases after Diamox in Group B (with persistent and severe migraine), were significantly greater compared with normals without headache, and with Group C consisting of migraineurs whose headaches had decreased, subsided, or become replaced by late-life migrainous accompaniments (Group C). Results establish that cerebrovasodilator capacitance declines with advancing age, probably due to progressive cerebral atherosclerosis, since these declines were accentuated by risk factors for stroke, particularly TIAs or documented lacunar infarcts by CT. Progressive impairments of cerebral vasodilator capacitance among migraineurs were associated with: (i) reductions in frequency and severity of migrainous cephalalgia and (ii) appearance of late-life migrainous accompaniments.